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  • 101
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of copolymers from acrylic and methacrylic acid with 2-methylaziridine by spontaneous copolymerization (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 231 (1995), S. 199-211 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 2-Methylaziridin (MAz) wurde als nukleophiles Monomeres mit den elektrophilen Monomeren Acrylsäure (AA) bzw. Methacrylsäure (MA) in unterschiedlichen Verhältnissen ohne Initiator copolymerisiert. Die Copolymeren wurden mittels Elementaranalyse, FT-IR- und 1H-NMR-Spektroskopie charakterisiert. Die Copolymerisationsparameter wurden mit den Methoden nach Fineman-Ross bzw. Kelen-Tüdős bestimmt. Für r1 und r2 wurden die Copolymerpaare MAz-AA und MAz-MA jeweils Werte 〈 1 ermittelt, was auf statistische Copolymere mit einer Tendenz zu alternierenden Copolymeren hinweist. Thermische Zersetzung mit einem Gewichtsverlust von 10% tritt bei den Copolymeren erst oberhalb 430 K auf. Der thermische Abbau verläuft nach einer Reaktion nullter Ordnung. Die kinetischen Parameter der Zersetzung der Copolymeren wurden bestimmt.
    Notes: 2-Methylaziridine (MAz) as a nucleophilic monomer and acrylic acid (AA) and methacrylic acid (MA), respectively, as electrophilic monomers were copolymerized in the absence of initiator at various feed ratios. Copolymers were characterized by elemental analysis, FT-IR and 1H-NMR spectroscopy. The monomer reactivity ratios were determined by the Fineman-Ross and Kelen-Tüdős methods. Values of r1 and r2 were found to be less than unity for MAz-AA, and MAz-MA, corresponding to random copolymers with the tendency to the alternance. For all the copolymers the thermal decomposition with 10% weight loss is higher than 430 K. The reaction order for degradation of all copolymers was zero. The kinetic parameters of the decomposition were determined for all copolymers.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052310117
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  • 102
    Electronic Resource
    Electronic Resource
    New trends in epr and epr kinetics studies in the stabilization mechanism by N-oxyl radicalsPaper presented at the “16th International Conference on Advances in the Stabilization and Degradation of Polymers” in Luzern (Switzerland), June 14-17, 1994. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 232 (1995), S. 45-63 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The mechanism of the solid state oxidation of isotactic polypropylene films and the the mechanism of inhibition by HALS have been investigated by kinetic-ESR and kinetic modelling with derivation of the rate constants for the sensitive steps in the reaction scheme. The results have shown the inadequacy of the Denisov cycle to account for the observed experimental kinetics of the intermediate nitroxyl radicals. The molecular dynamics associated with the oxidation inhibited by HALS in the polypropylene matrix has been investigated by applying the Liouville stochastic method to the analysis of the temperature effects of the ESR spectra of the intermediate nitroxyl radicals used as spin probes. The investigation on the nature and characteristics of the molecular motions available at the oxidation sites has also been carried out with nitroxyl spin labels bound to the PP chains. For this application a novel method of spin labelling was developed based on reactions with some of the oxidation products, namely the terminal and intrachain ketones (keana method), alcohols, peroxides and macroalkyl radicals.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052320104
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  • 103
    Electronic Resource
    Electronic Resource
    Aspects of stabilization with phosphorous antioxidants in polymersPaper presented at the “16th International Conference on Advances in the Stabilization and Degradation of Polymers” in Luzern (Switzerland). June 14-17, 1994. (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 232 (1995), S. 119-131 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: As plastics are being used in a variety of applications, demands on a greater level of processing stability are increasing. Phosphites are noteworthy as effective processing stabilizer and the performance of phosphite antioxidants can be correlated to the chemical structure of phosphites. Cyclic phosphite esters derived from 2, 2′ methylene bis-2, 4-di-tert-butylphenol and some commercially available phosphites were submitted to comparative studies. Decomposition of cumene hydroperoxide, melt flow of polypropylene and consumption of additives after multiple extrusions were investigated to understand the activity of phosphites as process stabilizers in polypropylene.This study suggests that phosphites play an important role in process stabilization when used in combination with sterically hindered phenols, and that the activity of phosphites may be predicted by their reactivity on hydroperoxide.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052320108
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  • 104
    Electronic Resource
    Electronic Resource
    Synthesis and properties of powdery hydrogels based on acrylamide, methacrylamide, and their N-substituted derivatives (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 243 (1996), S. 151-159 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Leicht vernetzte Hydrogele auf der Basis von Acrylamid, N-(1,1-Dimethyl-3-oxobutyl)acrylamid, N,N-Dimethylacrylamid, Methacrylamid, N-(2-Hydroxypropyl)-methacrylamid und N-[Tris(hydroxymethyl)methyl]methacrylamid wurden in Form von pulverigen Substanzen synthetisiert, die aus Aggregaten sehr kleiner Partikel (∼10-1 μm) bestehen. Die pulverartigen Hydrogele wurden durch Fällungspolymerisation in Aceton und Diethylether unter Verwendung von N,N′-Methylenbisacrylamid und Ethylendimethacrylat als Vernetzungsmittel synthetisiert. Es wurden die Abhängigkeiten des Quellungsgrades in Wasser, der Größe, des Aggregationsgrades und der spezifischen Oberfläche von Partikeln, und des Inhalts von wasserlöslichen Substanzen in den Hydrogelen von den Bedingungen ihrer Synthese verfolgt. Die Eignung einzelner der synthetisierten Hydrogele für die Herstellung von Silikon-kautschuk-Hydrogel-Kompositen wird diskutiert.
    Notes: Lightly crosslinked hydrogels based on acrylamide, N-(1,1-dimethyl-3-oxobutyl)-acrylamide, N,N-dimethylacrylamide, methacrylamide, N-(2-hydroxypropyl)methacrylamide and N-[tris(hydroxymethyl)methyl]methacrylamide were synthesized in form of fine powders, consisting of aggregates of very small (∼10-1 μm) particles. The powdery hydrogels were obtained by precipitation polymerization in acetone and diethyl ether, using N,N′-methylenebisacrylamide and ethylene dimethacrylate as crosslinking agents. Dependences of water-swellability, particle size, aggregation, specific surface and content of the uncrosslinked water-soluble polymers and low-molecular-weight substances in the hydrogels on the conditions of their synthesis were studied. Suitability of particular powdery hydrogels synthesized for the preparation of silicone rubber-hydrogel composites is discussed.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1996.052430113
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  • 105
    Electronic Resource
    Electronic Resource
    Polycarbonat-ein vielseitiger werkstoff mit zukunft (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 43-66 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The market development of bisphenol-A-polycarbonate has shown higher growth than any other engineering thermoplastic. The reasons can be found in the permanent improvement of the cost/performance-relationship and in the technical use of the variability of the basic structure. Incorporation of specific monomer units leads to tailor-made properties for a wide range of applications, as for example medical devices, electronic parts and glazing.This process has not yet slowed down, rather it is accelerated by new results from research and development. The improvement of flaw behavior and pit replication for new grades of materials for the next generation of compact discs, new grades that can be sterilized by γ-radiation without degradation and the microstructuring by low-energy laser systems are examples for the ongoing expansion of polycarbonate applications. Surface modification by hardcoatings with nanosized particles will allow to enter the fast growing market of glazing.
    Additional Material: 27 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440103
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  • 106
    Electronic Resource
    Electronic Resource
    Polyamide, polyester und polyoxymethylen. Die klassischen technischen kunststoffe und ihre perspektiven (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 67-92 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyamide, Polyester und Polyoxymethylen sind mit einem weltweiten Verbrauch von derzeit 2,4 Mio t pro Jahr wichtige technische Kunststoffe. Sie werden aufgrund ihrer besonderen Eigenschaftsprofile überwiegend im Fahrzeugbau und in der Elektroindustrie für hochbelastete Funktionsbauteile eingesetzt. Der vorliegende Beitrag behandelt Polymerisationswege, Eigenschaften und ausgewählte neue Entwicklungen dieser Polymerklassen.Teilaromatische Polyamide stoßen durch ihre Dimensionsstabilität und thermische Belastbarkeit in Anwendungen vor, die bisher Duromeren oder Metallen vorbehalten waren. Glasfaserverstärkte Polyamide mit besonders hoher Dauerwärmebeständigkeit übemehmen wichtige Funktionen im Motorbereich von Fahrzeugen. Polyamid-Blends sind als Karosseriewerkstoffe ein Schlüssel zu leichten Autos mit niedrigem Treibstoffverbrauch. Halogenfrei flammgeschützte Polyamide erhöhen Sicherheit und Umweltverträglichkeit in brandgefährdeten Anwendungsbereichen.Polybutylenterephthalat als technisch wichtigster Polyester eröffnet in Mischung mit amorphen Polymeren neue Perspektiven durch geringerenVerzug und bessere Oberfläche bei glasfaserverstärkten Teilen. Polybutylennaphthalat erweitert den Anwendungsbereich zu höheren Temperaturen. Von Polybutylenterephthalat abgeleitete Copolyester sind biologisch abbaubar und daher vielversprechend für kompostierbare Folien.Polyoxymethylen-Copolymere haben ihre Stärke in der günstigen Kombination aus Steifigkeit, Dimensionsstabilität, Gleit/Reibe-Verhalten und Beständigkeit gegen heißes Wasser und Kraftstoff.Aufgrund ihres hohen und noch weiter steigerungsfähigen Leistungsvermögens werden Polyamide, Polyester und Polyoxymethylen das in den letzten Jahren gezeigte Wachstum in Zukunft weiter ausbauen können.
    Notes: Polyamide, polyester and polyoxymethylene having presently a worldwide sales volume of 2,4 million tons a year are important engineering thermoplastics. Based on their special property profiles they are mainly used in the automotive and electronic industry for high performance functional parts. This contribution presents polymerisation processes, properties, and selected new developments for these polymer classes.Semiaromatic polyamides due to their dimensional stability and thermal resistance lend themselves to applications which were so far reserved for thermosets or metals. Glass fiber reinforce polyamides designed to have the highest possible heat ageing resistance can take important functions under the hood. A polyamide blend used as a material for exterior body parts is key to light weight cars with strongly reduced fuel consumption. Halogene free flame retardant polyamide increases fire safety and environmental safety in flame sensitive applications.Polybutyleneterephthalate as the technically most important polyester offers new perspectives in blends with amorphous polymers leading to lower distortion and better surface quality in glass fiber reinforced parts. Polybutylenenaphthalate is widening the range of application of polyesters towards higher temperatures. Copolyesters derived from polybutyleneterephthalate are biologically degradable and are therefore promising materials for fermentable foils.Polyoxymethylene copolymers show an outstanding combination of stiffness, dimensional stability, friction and wear as well as resistance against hot water and fuel.As a result of their excellent properties and the existing potential for further improvements polyamide, polyester and polyoxymethylene will continue to grow above average in the future.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440104
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  • 107
    Electronic Resource
    Electronic Resource
    Sind polyurethanwerkstoffe ein reifes gebiet? (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 244 (1997), S. 121-133 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The world-wide production of polyurethanes has exceeded 6 mio. metric tons in 1994. Compared with the produced amounts of large-scale thermoplastics such as PE, PVC, PP and PS, polyurethanes keep the 5th place.Polyurethanes (PUR) are segmented polymers, which can be synthesized from preformed building blocks in a modular unit construction system. The chemical modules and the various possibilities of combination will be discussed here.Tailor-made polyurethane materials can be divided into two main-fields of application: foams and compact PUR.The main constituents of polyurethane materials are diisocyanates and polyols. These key- chemicals are well characterised with respect to their technological, economical and ecological properties. Taking into account the availability, the masses of production and the experiences that have been collected with the PUR main constituents, these PUR precursors seem to be very mature already.In contrast to this, the PUR-materials made from these building blocks still offer numerous novel problem-solutions, resulting from the variability of the diisocyanate-poly-addition reaction: PUR materials are most commonly segmented into several phases. The formation of hard- and softsegments can be easily demonstrated by looking at thermoplastic polyurethanes (TPU). A deeper understanding of this phase separation and the molecular organisation within these materials promises to realize prospectic polymeric architectures with new and improved properties. PUR materials will still be able to offer new answers to future requirements in balancing economical and ecological needs. By looking at the life-cycles of soft and hard-foams, polyurethane-coatings and thermoplastic PUR-elastomers, this contribution will adress the question: “Is PUR-chemsitry still a challenging field?”
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052440106
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  • 108
    Electronic Resource
    Electronic Resource
    Fire-retardant action of potassium nitrate in polyamide 6 (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 23-35 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zugabe von 10-20 Gew.-% Kaliumnitrat (KN03) zu Polyamid 6 (PA 6) vermindert die Brennbarkeit des Polymeren. Das thermische Verhalten der KN03/PA 6-Mischung wurde mittels Thermogravimetrie, Differentialkalorimetrie und Analyse der fluchtigen Anteile untersucht. Feste Zersetzungsprodukte der Mischung wurden mittels Infrarotspektroskopie, Rontgendiffraktometrie und Elektronenresonanzspek-'troskopie analysiert. Es wurde gefunden, daß KNO3 dem Flielßen und Tropfen der Schmelze vorbeugt und die Karbonisierung auf der Oberflache des Polymeren fordert. Das verringert die Brandgefahr und verbessert die Feuerbestandigkeit. Andererseits geht KNO3 mit PA 6 in der kondensierten Phase eine exotherme Reaktion ein und setzt Sauerstoff frei, der wiederum die Brennbarkeit von PA 6 begiinstigt. Der Mechanismus der chemischen Wechselwirkung van KNO3 mit PA 6 wird diskutiert.
    Notes: The addition of 10-20 wt.-% of potassium nitrate (KNO3) to polyamide 6 (PA 6) improves the fire retardance of the polymer. The thermal decomposition behaviour of the PA 6/KN03-mixture was studied using thermogravimetry, differential scanning calorimetry and thermal volatilisation analysis. Solid products of the thermal decomposition of the mixture were analysed by infrared spectroscopy, X-ray diffraction and electron paramagnetic resonance. It was found that KNO, prevents flowing and dripping of the melt and promotes charring on the surface of the polymer which decreases its fire hazard and improves its fire retardance. On the other hand, KNO3 exothermally reacts with PA 6 in the condensed phase and supplies oxygen to the gas phase which increases the combustibility of PA 6. The mechanism of the chemical interaction of KN03 with PA 6 is discussed.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450103
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  • 109
    Electronic Resource
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    Effect of tricalcium phosphate, hydroxyethyl methacrylate, and ethylene glycol dimethacrylate on the mechanical properties of acrylic bone cement (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 49-62 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Einfluß einer Beimischung von Tricalciumphosphat (TCP), Hydroxyethylmethacrylat (HEMA) und Ethylenglycoldimethacrylat (EGDMA) auf die Eigenschaften eines chirurgischen Knochenzements wurde untersucht. Die in Zugversuchen entstandenen Bruchflächen wurden mittels Rasterelektronenmikroskopie charakterisiert. Der Einfluß der Additive auf den Temperaturanstieg während der Polymerisation wurde geprüft. Zug-, Biege- und Druckfestigkeit des ausgehärteten Zements nahmen mit zunehmendem TCP-Gehalt ab, der Elastizitätsmodul stieg dagegen an. Die Zugfestigkeit nahm mit steigendem HEMA-Gehalt geringfügig zu und blieb oberhalb 15 Gew.-% HEMA konstant. Zug-, Biege- und Druckfestigkeit zeigten bei einem EGDMA-Gehalt von 2 Gew.-% (in HEMA) ein Maximum. HEMA und EGDMA beschleunigten die Polymerisation, wogegen TCP retardierend wirkte.
    Notes: The effects of the addition of tricalcium phosphate (TCP), hydroxyethyl methacrylate (HEMA), and ethylene glycol dimethacrylate (EGDMA) on the properties of standard surgical Simplex-P radiopaque bone cement have been investigated. The fracture surface after tensile test was studied by scanning electron microscopy. The influence of these components on the temperature rise during polymerization was investigated. It was found that the tensile strength, the bending strength, and the compressive strength decreased with increasing TCP content, whereas the inverse was observed for the Young's modulus. The tensile strength slightly increased with increasing HEMA content and then it levelled off when the HEMA content was higher than 15 wt.-%. It seemed that there were maximum tensile, bending and compressive strengths when 2 wt.-% EGDMA (in HEMA) was added. Polymerization occurred more rapidly when HEMA and EGDMA were added, whereas the inverse result was found with TCP.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450105
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  • 110
    Electronic Resource
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    The relative physical and thermal properties of polyurethane elastomers. Effect of chain extenders derived from dihydroxynaphthalene (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 89-104 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polyurethanelastomere wurden in Gegenwart von zwei Dihydroxynaphthalin(DHN)-Verbindungen und deren bromierter Derivate als Kettenverlängerer hergestellt. Als Polyole wurden Polycaprolactondiol und Polytetramethylenglykol und als Diisocyanat-Komponenten Diphenylmethandiisocyanat (MDI) und Dicyclohexylmethan-4,4′-diisocyanat (HMDI) eingesetzt. Der Einfluß der Struktur der Kettenverlängerer auf die physikalischen und thermischen Eigenschaften der Polyurethane wurde untersucht. Wegen der besseren Phasenmischungswirkung der 1,5-DHN-Segmente haben die damit hergestellten Polyurethane höhere Glasübergangstemperaturen und bessere dynamische Eigenschaften als die Polyurethane auf 2,7-DHN-Basis. Der Einbau von bromierten DHN-Einheiten erschwert die Entflammbarkeit. Durch das große freie Volumen der Bromatome wird jedoch die Rotation der DHN-Einheiten eingeschränkt, was zu Polyurethanen mit verringerten Phasenmischungs- und Kristallisationsgraden führt. Die bromhaltigen Polyurethane zeigen zudem eine Verschlechterung der mechanischen und physikalischen Eigenschaften und eine erhöhte Löslichkeit.
    Notes: Polyurethane elastomers were synthesized based on polyols such as poly(caprolactonediol) and poly(tetramethylene glycol), diisocyanates such as diphenylmethane-4,4′-diisocyanate (MDI) and dicyclohexylmethane-4,4′-diisocyanate (HMDI), and two dihydroxynaphthalenes (DHNs) and their brominated derivatives used as chain extenders. The effects of the chemical structures of the chain extenders on the physical and thermal properties of the polyurethanes were investigated. Because of the higher degree of phase mixing of the 1,5-DHN unit, the 1,5-DHN-based polyurethanes have higher Tg values and higher dynamic properties than 2,7-DHN-based polyurethanes. Introduction of bromine atoms increased the flame retardance. However, the large free volume of bromine atoms restricted the rotation of DHNs, thus, directly decreasing the degree of phase-mixing and crystallinity of the polyurethanes. Introducing bromine atoms also decreased the mechanical and dynamic properties and increased the solubility of the polyurethanes.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450108
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  • 111
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    Synthesis and characterization of polypyrrolepolyurethane cationomer composites (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 139-147 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aus Poly(oxytetramethylen), 4,4′-Bibenzyldiisocyanat, N-Methyldiethanolamin als Kettenverlängerer und Acrylsäure/Polyacrylsäure als Quaternisierungsagens wurden Poly(etherurethan)-Kationomere hergestellt. In aus diesen Kationomeren hergestellten Filmen wurde Pyrrol (15 Gew.-%) in Gegenwart von CuCl2 polymerisiert. Die Filme wurden mittels dynamisch-mechanischer Analyse, Thermogravimetrie und Differentialthermoanalyse charakterisiert. Die elektrische Leitfähigkeit beträgt für den Film ohne Polypyrrol 7.5 · 10-12 Ω-1 cm-1 und mit Polypyrrol 4.5 · 10-6 Ω-1 cm-1.
    Notes: Poly(ether urethane) cationomers based on poly(oxytetramethylene), 4,4′-bibenzyldiisocyanate, N-methyldiethanolamine as chain extender, and acrylic acid/poly(acrylic acid) as quaternization agent were synthesized. Pyrrole (15 wt.%%) was polymerized in films of the ionomer containing CuCl2. The films were characterized by dynamic mechanical analysis, thermogravimetry and differential scanning calorimetry. The electric conductivity of the film without polypyrrole is 7.5 · 10-12 Ω-1 cm-1, while incorporation of polypyrrole increases the conductivity to 4.5 · 10-6 Ω-1 cm-1.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450112
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  • 112
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    Synthesis, characterization and polymerization of waxy monomers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 155-164 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Wachsartige Monomere und Vernetzer wurden aus kommerziellen Wachsen durch Veresterung mit 2-Hydroxyethylmethacrylat, Glycerindimethacrylat oder Glycidylmethacrylat oder durch Funktionalisierung mit 2-Isocyanatoethylmethacrylat synthetisiert. Die erhaltenen opaken Methacrylate mit Schmelzpunkten zwischen 45 und 80°C wurden in Substanz bzw. Toluollösung in Gegenwart von Radikalinitiatoren polymerisiert. Die Polymeren zeichnen sich durch eine breite Molmassenverteilung aus. Im Gegensatz zur Substanzpolymerisation ist der Doppelbindungsumsatz nach der Lösungspolymerisation nahezu vollständig. Aufgrund der hohen Molmasse der Monomeren ist der beobachtete Polymerisationsschrumpf sehr gering. Polymerisate mit Vernetzermonomeren zeigen eine verbesserte mechanische Stabilität.
    Notes: Waxy monomers and crosslinkers, respectively, were synthesized from commercially available waxes by esterification with 2-hydroxyethyl methacrylate, glycerol dimethacrylate, or glycidyl methacrylate or by functionalization with 2-isocyanatoethyl methacrylate. The resulting opaque methacrylates with melting points between 45 and 80°C were polymerized in bulk and in toluene solution in presence of free radical initiators. The obtained polymers were characterized by a broad molecular weight distribution. Opposite to the bulk polymerization, the double bond conversion in solution polymerization is nearly quantitative. The observed volume shrinkage during polymerization is very low due to the high molecular weight of the monomers. Polymerizates containing crosslinking comonomers exhibit improved mechanical stability.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052450114
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  • 113
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    Zur Kinetik der stabilisierten Fällungs-polymerisation eines Kationischen Monomeren in wäßrigen Natriumchlorid-Lösungen (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 245 (1997), S. 165-181 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The stabilized free-radical precipitation polymerization of the cationic monomer N-(2-methacryloyloxyethyl)-N,N-dimethylbenzylammonium chloride (MADAMBQ) in aqueous solutions of sodium chloride was studied by reaction calorimetry. Poly(ethylene oxide) was used as stabilizer. The rate of polymerization reaches its maximum immediately after initiation and remains nearly constant up to 50 % conversion followed by a decrease that could be described by a first order kinetics. The particles formed are approximately 1 to 30 μm in diameter and are stable over a period of several months.A model based on the theory of homogeneous particle nucleation is suggested to describe the kinetic course of polymerization, taking into account the rate of polymerization in both phases. With the assumption that the concentration of monomer in the phases is determined by a Nernst distribution law, the kinetics of the early stage of polymerization can be modelled reasonably well.The solution polymerization and the unstabilized precipitation polymerization of MADAMBQ was also studied.
    Notes: Die Kinetik der stabilisierten Fällungspolymerisation des kationischen Monomeren N-(2-Methacryloyloxyethyl)-N,N-dimethylbenzylammoniumchlorid (MADAMBQ) in wäßrigen Natriumchlorid-Lösungen wurde mittels Reaktionskalorimetrie untersucht. Polyethylenoxid höherer Molmasse wurde als Stabilisator eingesetzt. Die Reaktionsgeschwindigkeit ist über einen größeren Umsatzbereich nahezu konstant und fällt anschließend mit dem Umsatz annähernd linear ab. Die Teilchengrößenverteilung der gebildeten Dispersion ist bimodal mit Teilchen von etwa 1 bis 30 μm Durchmesser.Zur Beschreibung des Geschwindigkeitsverlaufs der Fällungspolymerisation wird ein Modell vorgeschlagen, das die Polymerisation in der Wasser- sowie in der Polymerphase berücksichtigt. Die Teilchenbildung soll durch homogene Nukleierung erfolgen. Es wird angenommen, daß die Konzentration des Monomeren in den Phasen durch ein Nernstsches Verteilungsgleichgewicht bestimmt wird. Zu Vergleichszwecken wurde auch die Polymerisation von MADAMBQ in Lösung und als nicht stabilisierte Fällungspolymerisation durchgeführt.
    Additional Material: 8 Ill.
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    An investigation of the grafting of cellulose powder with acrylamide under a magnetic field (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 1-9 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Cellulosepulver, hergestellt durch Nitrierung von Eichen-Furfural-Lignocellulose, wurde mit Acrylamid radikalisch gepfropft. Die Pfropfreaktion wurde sowohl in Gegenwart eines äußeren Magnetfeldes (0,15-0,35 T) als auch ohne Magnetfeld durchgeführt. Der Einfluß von Monomerkonzentration, Initiatorkonzentration, Polymerisationszeit und temperatur sowie der magnetischen Feldstärke auf den Polymerisationsverlauf wurde untersucht. Es wurde festgestellt, daß der Pfropfumsatz mit zunehmender Feldstärke signifikant ansteigt.
    Notes: Cellulose powder obtained from oak furfural lignocellulose by nitration reaction was grafted with acrylamide using a radical initiation. The grafting reactions were carried out and compared both in presence and in absence of a continuous external magnetic field with the intensity extended between 0.15-0.35 T. The effect of monomer and initiator concentration, time and temperature of reaction and magnetic field intensity onto the grafting process were examined. It was observed that the presence of a magnetic field leads to a significant increase of the graft conversion.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052460101
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    Radical polymerization of poly(butyl acrylate) in the presence of poly(L-lactic acid), 1. Synthesis, characterization and properties of blends (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 49-63 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(L-milchsäure) ist ein biokompatibler, semikristalliner, thermoplastischer Polyester mit ungünstigen mechanischen Eigenschaften. Daher wurde in einem “reactive blending”-Prozeß ein Acrylkautschuk, n-Butylacrylat, mittels einer Suspensionspolymerisation in Wasser auf in einem organischen Lösungsmittel gelöste Poly(L-milchsäure) gepfropft. Die gebildeten Copolymeren konnten isoliert und durch NMR-Spektroskopie und DSC-Messungen charakterisiert werden. Die Untersuchung der mechanischen Eigenschaften ergab keine befriedigenden Ergebnisse, weil die Kautschukphase wahrscheinlich aus viskosen linearen Makromolekülen besteht und daher keine elastischen Eigenschaften besitzt. In weiteren Arbeiten soll der Syntheseweg so modifiziert werden, daß durch den Einbau von Diacrylaten eine zumindest partielle Vernetzung der Kautschukphase erreicht wird.
    Notes: Poly(L-lactic acid) is a biocompatible polyester, semicrystalline, thermoplastic, with low versatility in mechanical properties. To overcome this problem, a reactive blending procedure was performed by grafting an acrylic rubber, n-butyl acrylate, via water suspension polymerization onto poly(L-lactic acid) dissolved in an organic solvent. It was possible to isolate the copolymeric phase formed from the two polymers and characterize it by using NMR and DSC techniques. Mechanical tests on blends gave no satisfactory response, probably because the rubbery phase is composed essentially of viscous linear macromolecules, not able to perform elastic properties. Work is in progress to modify the synthetic pathway to incorporate diacrylates in order to realize a rubbery phase at least partially cross-linked.
    Additional Material: 7 Ill.
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    Tin-coupled styrene-butadiene rubbers (SBRs). Relationship between coupling type and propertiesBased on a paper presented at the 148th Meeting of the Rubber Division, American Chemical Society, Cleveland, Ohio, 17-20 October 1995. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 85-96 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zur Entwicklung von neuen Styrol-Butadien-Kautschuken (SBRs) für Reifenanwendungen sind mehrere Arten von Zinn-Polymer-Bindungen (Styryl-, Butadienyl-, Isoprenyl- and α-Methylstyryl-Zinn) sowohl in linearen als auch in verzweigten Ketten untersucht worden. Die dynamisch-mechanischen Eigenschaften von Vulkanisaten mit Ruß wurden analysiert, um eine Beziehung zwischen den Strukturparametern der Polymeren und den Materialeigenschaften herzustellen. Der Polymer-Füll-stoff-Wechselwirkungsparameter, der durch das Verhältnis von mechanischen und dynamischen Termen definiert ist, wurde zur Charakterisierung der Verbindungen herangezogen. Der Einbau von verschiedenen Zinn-Polymer-Bindungen in lineare und in verzweigte SBR-Ketten bewirkte eine Verbesserung der Hystereseeigenschaf-ten der Vulkanisate und eine Veranderung des Wechselwirkungsparameters.
    Notes: Following the development of new SBRs for tyre applications, several kinds of tin-polymer bonds (styryl-, butadienyl-, isoprenyl- and α-methylstyryltin) have been studied, in both branched and linear chains.Dynamic-mechanical properties of the carbon black vulcanizates have been analyzed to establish a relationship between structural parameters of polymers and compound properties. The filler-polymer interaction parameter, defined by a ratio of mechanical and dynamic terms, has been used for the evaluation of the compounds. The introduction of different types of tin-polymer bonds, in branched and linear chains of the SBRs, implies an improvement in the hysteresis properties of the vulcanizates as well as a modification of the interaction parameter.
    Additional Material: 1 Ill.
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    A novel spin-finishing method for antistatic modification of polyester fiber. Surface reaction onto amine-containing copoly(amide-ethers) blended with polyester fiber (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 246 (1997), S. 109-123 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copoly (amid-ether) rnit zwei unteschiedlichen Aminfunktionalitäten wurden als antistatische Modifikatoren für Polyethylenterephthalatfasern (PET) eingesetzt. Die tertiären Aminogruppen schmelzegesponnener Copolymerfilamente wurden rnit drei Alkylierungsmitteln umgesetzt, wobei ein Sulfobetain, ein Carbobetain bzw. Ammoniumionen gebildet wurden. Dadurch wurde der scheinbare spezifische Widerstand der Filamente auf größfienordnungsmäßfiig 106 bis 108 Ω/cm verringert. Da sich die quaternisierten Copolymeren beim Blend-Spinnen rnit PET zersetzen, wurden Blendfasern von PET mit einem Copolymeren nach dem Schmelzespinnen einer Quaternisierung oder Vernetzung rnit Alkylierungsmitteln bzw. Epoxyvernetzern unterzogen, was die antistatischen Eigenschaften der Fasern im Vergleich rnit der unbehandelten Faser verbesserte. Insbesondere die mit Epoxiden vernetzten Fasern wiesen antistatische Eigenschaften auf, wie sie mit dieser Modifizierungsmethode bislang nicht erreicht wurden. Die antistatischen Eigenschaften blieben nach dem Fkben erhalten, da sowohl die hydrophilen als auch die ionischen Gruppen auf der Faseroberflache immobilisiert waren. Da Quaternisierung bzw. Vernetzung in einem Arbeitsgang rnit dem Verspinnen und Verstrecken der Fasern innerhalb einer kurzen Reaktionszeit erfolgen, sollte diese “spin-finishing„ genannte Methode konventio- nellen Verfahren bezuglich Kosten und Produktivitat uberlegen sein.
    Notes: Copoly(amide-ethers) containing two types of tertiary amine units were made as antistatic modifiers for poly(ethylene terephthalate) (PET) fibers. The filaments of the copolymers were melt-spun and reacted with three alkylating agents in order to quaternize the tertiary amine into a sulfo-betaine, a carbobetaine, and an ammonium ion. The apparent electric resistivity of the filaments was greatly reduced by this reaction, being in the range of 106 to 108 Ω/cm. However, because these quaternized copolymers incurred decomposition during blend spinning with PET, a blend PET fiber containing one type of copoly(amide-ether) was melt-spun and subjected to quaternization of the amino groups as well as to surface crosslinking with various alkylating and epoxy agents. The quaternized blend fibers obtained showed improved antistatic properties compared with the original blend fiber. Particularly, the fibers crosslinked with epoxy compounds were found to have the best antistatic properties that had ever been attained with this type of modification. The antistatic properties were retained even after dyeing, because both hydrophilic and ionic groups had been effectively immobilized on the surface. Since this quaternization and crosslinking could be conducted on-line with spinning and drawing within a short reaction time, this modification technique is called “spin-finishing method”, which should be superior to the conventional methods in terms of cost performance and productivity.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052460109
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    Etching of a low-density polyethylene film by fuming nitric acid (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 33-46 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Filme aus Polyethylen niedriger Dichte (LDPE) wurden mit rauchender Salpetersäure behandelt. Die Oberflächeneigenschaften sowie die Bildung polarer Gruppen wie auf der geätzten Filmoberfläche wurden mit SEM-, IR- und XPS-Methoden analysiert. Die mechanische Festigkeit eines aus dem geätzten LDPE-Film und einem Epoxidharz hergestellten Laminats sowie die Bedruckbarkeit der geätzten Oberflächen wurden untersucht und mit einer unbehandelten Probe verglichen. Die Oberflächenrauhigkeit und die Gegenwart polarer Gruppen erhöhen die mechanische Festigkeit des Laminats aus dem geätzten Film durch mechanische Verankerung und chemischer Wechselwirkungen. Die Oberfläche des behandelten LDPE-Films ist besser bedruckbar als die des unbehandelten Films.
    Notes: Low-density polyethylene (LDPE) films were treated with fuming nitric acid (FNA). The surface characteristics and also the insertion of polar groups like on the etched LDPE film surface were measured by SEM, IR and XPS analyses, respectively. The mechanical performance of a laminate of the etched film with epoxy resin and also the printability of the etched film surface were tested and compared with the unetched sample. The surface roughening and the presence of polar groups enhance the mechanical strength of the laminate of FNA-treated film due to mechanical interlocking and chemical interaction. The printability of the treated film surface is also superior to that of the untreated LDPE film surface.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052490103
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    Polymerization of lactams, 87Part 86 cf.21.. Block copolymers of poly(∊-caprolactam) and polybutadiene prepared by anionic polymerization. Part I: Preparation and properties (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 237 (1996), S. 123-141 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Es wurde der Einfluß der Polymerisationsbedingungen auf die Eigenschaften von Poly(∊-Caprolactam)-Polybutadien-Blockcopolymeren untersucht, die durch Reaktionsformgießen bei der anionischen ∊-Caprolactam-Polymerisation, initiiert durch das ∊-Caprolactam-Kaliumsalz, in Anwesenheit von α,ω-Dihydroxypolybutadien und Isocyanaten oder deren blockierter Derivate als Funktionalisierungsmittel hergestellt wurden.Es wurde der Einfluß des Polybutadiengehalts, dessen Molekulargewichts, des Isocyanat-Typs und der Polymerisationstemperatur auf die mechanischen Grundeigenschaften und auf die Polymerisationsgeschwindigkeit bestimmt.
    Notes: The effect of the polymerization conditions on the properties of poly(∊-caprolactam)-polybutadiene block copolymers prepared by polymerization casting through anionic polymerization of ∊-caprolactam initiated with potassium salt of ∊-caprolactam in the presence of α,ω-dihydroxy-polybutadiene and isocyanates or their blocked derivatives as functionalizing agents was investigated.The influence of the content of telechelic polybutadiene, its molecular weight, type of diisocyanate, and polymerization temperature on the fundamental mechanical properties of the prepared materials and on the polymerization rate was evaluated.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052370107
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    Celluloseether als Trennschichten hydrophiler Polymermembranen (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 249 (1997), S. 11-32 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: This paper reports on polymer membranes characterized by a surface layer of hydroxyalkyl derivatives of cellulose. Water compatible polymers like hydroxyalkyl derivatives of cellulose are preferably those exhibiting good chemical stability and desired membrane characteristics. Normally, water-compatible polymers used in the coating solutions must be rendered water-insoluble after coating. By adapting crosslinking conditions on separation problems, the membranes are useful for many processes in the fields of biotechnology, food and chemical industry.The membranes presented here possess the advantage of being highly resistant to chemical and biological degradation and, hence, have long lifetimes under many process conditions.
    Notes: Es wird die Entwicklung hydrophiler Polymermembranen diskutiert, die nach Beschichtung mit Celluloseethern und anschließender Vernetzung auf den asymmetrischen Trägermembranen interessante Permeations- und Trenneigenschaften bei hervorragenden chemischen Stabilitäten, vor allem beim Membrantrennverfahren der Nanofiltration, aufzeigen. Weiterhin werden Aussagen zu den Gastrenneigenschaften der Celluloseetherkompositmembranen getroffen.Erläutert werden die Permeations- und Trenndaten der Kompositmembranen in Korrelation zur Vernetzung der Celluloseether anhand verschiedener Einflußgrößen, was qualitative und gegebenenfalls quantitative Aussagen zum Vernetzungsmechanismus der Celluloseetherderivate erlaubt. Dabei stehen die Vernetzungstemperatur, der Einfluß der katalysierenden Wasserstoffionen und bedingt die Vernetzungszeit im Vordergrund. Abgerundet werden die Arbeiten durch Ermittlungen rheologischer Daten, die in Zusammenhang zu den Vernetzungsreaktionen und damit zu membranspezifischen Größen stehen.Infolge der hervorragenden chemischen Stabilität der Celluloseether werden Einsatzmöglichkeiten der Kompositmembranen zur Nanofiltration niedermolekularer Verbindungen aus organisch hochbelasteten Systemen beschrieben.
    Additional Material: 30 Ill.
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    Synthesis of tetrahydrofuran-styrene and tetrahydrofuran-methyl methacrylate block copolymers via poly(tetrahydrofuran) with azo groups (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 55-62 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Tetrahydrofuran (THF) wurde mit dem Initiatorsystem 4,4′-Azobis(4-cyanopentanoylchlorid)/SnCI4 kationisch polymerisiert. Das gebildete Poly(THF) mit je einer Azogruppe in der Hauptkette wurde als Initiator für die Polymerisation von Styrol (S) und Methylmethacrylat (MMA) bei 70°C eingesetzt. Die dabei entstandenen PTHF-PS-PTHF- bzw. PTHF-PMMA-Blockcopolymeren wurden mittels Fällungsfraktionierung, spektroskopischen Methoden und Viskositätsmessungen charakterisiert.
    Notes: The cationic polymerization of tetrahydrofuran (THF) initiated by 4,4′-azobis(4-cyanopentanoyl chloride) (ACPC) and SnCI4 is described. Poly(THF) samples possessing azo gorups in the main chain thus obtained were used as initiator in the polymerization of styrene (S) and methyl methacrylate (MMA) at 70°C to yield PTHF-PS-PTHF and PTHF-PMMA block copolymers. Characterization of the block copolymers was carried out by fractional precipitation, spectroscopic methods and viscosity measurements.
    Additional Material: 3 Ill.
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    The effects of a slushing oil on the curing and degradation behavior of an oil-accommodating epoxy adhesive (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 238 (1996), S. 129-141 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Wirkung von aliphatischem Korrosionsschutzöl auf das Aushärte- und Abbauverhalten eines ölkompatiblen Epoxidharzklebers wurde mittels Differentialkalorimetrie (DSC), Fourier-Transformations-Infrarot-Spektroskopie (FTIR) und Thermogravimetrie (TGA) untersucht. Die Ergebnisse der DSC- und FTIR-Messungen deuten darauf hin, daß die Härtungsgeschwindigkeit des untersuchten Epoxid-Systems durch das Vorhandensein des Öls nur wenig beeinflußt wird. Dennoch bestätigt das Absinken der exothermen Härtungskurve, begleitet von einer Verbreiterung des Glasübergangstemperaturbereichs, daß das Öl den Aushärtemechanismus beeinflussen kann und in der Lage ist, die Struktur des gehärteten Harzes zu verändern. Außerdem geht aus den TGA-Messungen hervor, daß die Temperaturbeständigkeit des Harzes sich in Gegenwart des Öls verschlechtert; dies wird auf Veränderungen in der Struktur und im Abbaumechanismus des Epoxid-Systems zurückgeführt.
    Notes: The effect of aliphatic slushing oil on the curing and degradation behavior of an oil-accommodating epoxy adhesive is studied by using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). The results of FTIR and DSC indicate that the curing rate of the tested epoxy system is little affected in the presence of the oil. However, the decrease of the curing exotherm accompanied with a broadening of the glass transition confirms that the oil can affect the curing mechanisms and may change the structure of the cured resin. Additionally, it is evident from the TGA results that the thermal resistance of the resin deteriorates in the presence of the oil, which is attributed to the changes in the structure and the degradation mechanism of the epoxy system.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052380112
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    Electrochemical polymerization of some monomers with schiff's base structure. A voltammetric study (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 1-12 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die elektrochemische Polymerisation von Pyrrol-2-aldehyd-azin, 2,2′-[1,4-Phenylenbis(nitrilomethylidyn)]dipyrrol und 2,2′-[1,4-Biphenylylenbis(nitrilomethylidyn)]dipyrrol läuft als anodische Fällungspolymerisation ab. Monomere und Polymere wurden voltammetrisch unter Verwendung von Platin- und “Paste-carbon”-Elektroden untersucht. Die Ergebnisse stimmen mit MO-Berechnungen überein, wobei die Reaktivität der Monomeren nach Hückel abgeschätzt wurde.
    Notes: The electrochemical polymerization of some Schiff's base-type monomers like pyrrole-2-aldehyde azine, N,N′-di(2-pyrrolylmethylene)-1,4-diaminobenzeneSystematic name: 2,2′-[1,4-phenylenebis(nitrilomethylidyne)]dipyrrole., and N,N′-di(2-pyrrolylmethylene)-4,4′-diaminobiphenylSystematic name: 2,2′-[4,4′-biphenylylenebis(nitrilomethylidyne)]dipyrrole. proceeds as a precipitating polymerization to the anodic compartment. The voltammetric study of monomers and polymers using Pt electrodes and paste-carbon electrodes were carried out. The results are in agreement with the MO calculations using the Hückel approximation for evaluating of the reactivity of the monomers.
    Additional Material: 7 Ill.
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    Stereoselective polymerization of butadiene by a new dicationic nickel complex (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 33-41 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der neuartige dikationische Komplex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-Bis(diphenylphosphin)ferrocen) zeigte in Anwesenheit von Diethylaluminiumchlorid (AIEt2CI) hohe Aktivität für die Polymerisation von 1,3-Butadien. Reaktionsdauer, Temperatur und das Aluminium/Nickel-Verhältnis wurden auf maximale Aktivität und Selektivität optimiert. Umsätze über 90% konnten erreicht werden. Im Vergleich zu Polybutadienen, die mit anderen Nickel-Phosphin-Systemen hergestellt wurden, zeigten die synthetisierten Polybutadiene höhere cis-1,4-Anteile (〈80%) und eine geringe Bildung von 1,2-Einheiten (2%). Alle Polymeren hatten niedrige mittlere Molekulargewichte (Mw 〉 11 800).
    Notes: The new dicationic nickel complex [dppfNi(MeCN)4][BF4]2 (dppf = 1,1′-bis(diphenylphosphino)ferrocene) in the presence of diethylaluminium chloride (AIEt2CI) exhibited high activity on the 1,3-butadiene polymerization. Reaction time, temperature and aluminium/nickel molar ratio were optimized in order to achieve maximum activity and selectivity. Conversions higher than 90% were obtained in contrast to other nickel-based systems using phosphine ligands, the resulting polybutadiene showed high cis-1,4 (〈80%) content and only small amount of 1,2-units (2%). All polymers presented low molecular weights (Mw 〉 11 800).
    Additional Material: 2 Ill.
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    Structural changes in poly(methyl methacrylate) during deep-etch X-ray synchrotron radiation lithography. Part II: Radiation effects on PMMAPart I cf.1. Dedicated to Prof. Dr. Werner Borchard on the occasion of his 60th birthday (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 79-91 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bei der Bestrahlung von Polymethylmethacrylat (PMMA) mit Röntgensynchrotronstrahlung ändert sich die chemische Struktur des Polymeren. Die Ergebnisse der analytischen Untersuchungen dieser Arbeit weisen darauf hin, daß neben einem Abbau der Polymerketten auch einzelne Esterseitengruppen abgespalten werden. Durch die Bestrahlung entstehende Langkettenverzweigungen wurden bei PMMA nicht gefunden. Dadurch unterscheiden sich die physikalischen und chemischen Eigenschaften des bestrahlten Polymeren von denen des unbestrahlten.
    Notes: The irradiation of poly(methyl methacrylate) changes the chemical constitution of the polymer. In addition to a decrease in molar mass further radiation-induced radical reactions cause changes in the chemical constitution of the polymer. Analysis of the reaction products shows that formation of long-chain branching can be excluded. Along with degradation of the chain lengths, ester groups in the side chains are attacked. The result is a modified polymer with a physical and chemical behaviour different from that of the starting polymer.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052390108
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    Synthesis of flexible polyarylates by interfacial polycondensation. Part II: Incorporation of 4,4′-thiodiphenol (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 133-149 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zähigkeit von Polyarylaten wurde durch den Einbau von 4,4′-Thiodiphenol und Bisphenol A, die in der wäßrigen Phase einer Grenzflächenpolykondensation vorgelegt wurden, erhöht. Die modifizierten Polyarylate besitzen leicht erniedrigte Zugfestigkeiten und Zugmoduli, aber aufgrund der Flexibilität der eingebauten Segmente stark erhöhte Izod-Schlagzähigkeiten. Darüber hinaus bleiben die guten thermischen Eigenschaften der Polyarylate nach der Modifizierung erhalten, so daß die hergestellten Materialien auch für Anwendungen mit sehr hohen Anforderungen an die thermische Belastbarkeit geeignet sind.
    Notes: The toughness of polyarylates was improved by incorporation of 4,4′-thiodiphenol and bisphenol A, being introduced in the aqueous phase of an interfacial polycondensation reaction. The modified polyarylates possessed slightly lower tensile strength and modulus but much higher Izod impact strength due to the flexibility of the incorporated segments. In addition, the superb thermal properties typical for polyarylates were reserved in the modified polyarylate, thus assuring its broad applicability for those applications where extremely stringent criteria of thermal characteristics are required.
    Additional Material: 16 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052390112
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    Le rôle des systèmes photoamorceurs dans l'efficacité de photoréticulation de l'homopolymère dicyclopentadiène acrylateNom systématique: Tricyclo[5.2.1.02.6]déc-4-en-8-yl acrylate. (DCPA) et acrylate d'éthyle (AE) et des dérivés copolymères DCPA/AE (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 239 (1996), S. 169-190 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: The photocrosslinking efficiency of a series of commercial photoinitiators and multicomponent photosensitive systems on uncrosslinked acrylic matrices has been estimated. Copolymers used for this study are tricyclo[5.2.1.02,6]dec-4-en-8-yl acrylate/ethyl acrylate copolymers of variable composition (100/0, 40/60, 20/80, 0/100) synthesized in solution by a free-radical process. The irradiations were carried out at large wavelengths (λ ≥ 310 nm). Systems of benzophenone/benzoyl peroxide led to really fast crosslinking kinetics for 10 min of irradiation.
    Notes: L'efficacité de photoréticulation de toute une série de photoamorceurs commerciaux et de systèmes photosensibles multicomposants a été évaluée sur des matrices acryliques non réticulées. Les polymères utilisés pour cette étude sont des homopolymères et des copolymères d'acrylate de dicyclopentadiène/acrylate d'éthyle de composition variable (100/0, 40/60, 20/80, 0/100) synthétisés en solution par voie radicalaire. Les irradiations ont été effectuées à des grandes longueurs d'ondes (λ ≥ 310 nm). Les systèmes benzophénone/peroxyde de benzoyle ont permis d'obtenir des cinétiques de réticulation très rapides pour des temps d'irradation de 10 min.
    Additional Material: 12 Tab.
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    Products of polycondensation of 4,4′-biphenyldithiol with some hydrocarbon dihalides (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 13-21 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Polysulfide wurden mit hoher Ausbeute durch Hochtemperatur-Lösungspolykondensation von 4,4′-Dimercaptobiphenyl mit ausgewählten aliphatischen und aromatisch-aliphatischen Dihalogenkohlenwasserstoffen hergestellt. Um die optimalen Polykondensationsbedingungen zu bestimmen, wurde der Einfluß folgender Faktoren auf die reduzierte Viskosität und die Ausbeute der Polysulfide ermittelt: Art des organischen Lösungsmittels, Art des Halogenwasserstoff-Akzeptors, Konzentration der organischen Reagenzien, Reaktionstemperatur und -zeit. Die Polykondensation des Dithiols mit Bis(4-chlormethylphenyl)methan wurde als Modellsystem eingehender untersucht. Die Polysulfidstrukturen wurden mittels Elementaranalyse, IR-Spektroskopie und Röntgenstrukturanalyse bestätigt. Aus der thermogravimetrischen Analyse wurden die Zersetzungstemperatur, der Gewichtsverlust bei dieser Temperatur und das Maximum der Zersetzungsgeschwindigkeit erhalten. Weiterhin wurden einige physikalisch-chemische, mechanische und dielektrische Eigenschaften ermittelt. Die beste thermische und chemische Bestandigkeit zeigt das aus dem Dithiol und 4,4′-Bis(chlormethyl)biphenyl hergestellte Polysulfid, was auf dessen vorwiegend aromatische Struktur zuriickgefuhrt werden kann.
    Notes: Polysulfides were synthesized with high yield by high-temperature solution polycondensation of 4,4′-biphenyldithiol with selected aliphatic and aromatic-aliphatic hydrocarbon dihalides. To determine the optimum polycondensation conditions, the influence of the following factors on reduced viscosity and yield was studied: type of organic solvent, type of hydrogen halide acceptor, concentration of reagents, reaction temperature, and reaction time. A thorough examination was carried out only for the polycondensation of dithiol with bis(4-chloromethylphenyl)methane chosen as model system. The structures of the polysulfides were confirmed by elemental analysis, X-ray analysis, and infrared spectroscopy. The temperature of initial decomposition, the percentage of mass loss, and the temperature of the fastest decomposition, process were determined from curves of differential thermal and thermogravimetric analysis. Some physicochemical, mechanical and electrical properties were determined. The highest thermal and chemical resistance has been found for the polysulfide obtained from 4,4′-biphenyldithiol and 4,4′-bis(chloromethyl)biphenyl, probably because of the predominantly aromatic structure.
    Additional Material: 4 Ill.
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    Organic-inorganic hybrid sol-gel materials, 2. Application for dental composites (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 61-72 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Drie organisch-anorganische Hybridmaterialien wurden nach dem Sol-Gel-Verfahren durch kovalenten Einbau von Poly(styrol-co-methylmethacrylat)(Poly(St-co-MMA))-, Polymethylmethacrylat(PMMA)- und Polystyrol(PS)-Struktureinheiten in ein SiO2-Netzwerk hergestellt und als Füllstoffe (bis zu 60 Gew.-%) in Dentalharzen verwendet. Der Einfluß der Füllstoffe auf einige mechanische Eigenschaften der Harze wurde untersucht. Die Härte der gefüllten Dentalharze nahm mit steigendem Füllstoffgehalt zu, wogegen die Biegefestigkeit abnahm. Die Druckfestigkeit der gefüllten Harze war besser als die des ungefüllten Harzes, nahm jedoch mit steigendem Füllstoffgehalt ab.
    Notes: By incorporating poly(methyl methacrylate) (PMMA), polystyrene (PS), and poly(styrene-co-methyl methacrylate) (poly(St-co-MMA)) structure units covalently into the SiO2 glass network via a sol-gel approach, three organic-inorganic hybrid materials (PMMA-SiO2, PS - SiO2, and poly(St-co-MMA) - SiO2) have been prepared. The three hybrid sol-gel materials were used as filler (up to 60 wt.-%) for dental composite resins. The effect of the three filler materials on several mechanical properties of the dental composite resins was investigated. The hardness of the filled dental composites increased with increasing filler content, whereas the bending strength decreased. The compressive strength of the composites was improved, compared with the unfilled resin, but decreased with inreasing filler content.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052510106
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    Adsorption of BTX compounds from aqueous solutions by water-insoluble starch (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 107-116 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Adsorption von Benzol, Toluol und p-Xylol (BTX) aus wäßrigen Lösungen mittels hochvernetzter kationischer Stärke mit tertiären Amingruppen wurde untersucht. Der endotherme Adsorptionsvorgang ist vom Anfangs-pH-Wert und der Anfangskonzentration abhängig und kann mit einer Langmuir-Isotherme beschrieben werden.Die Adsorptionswärme (Δ) bei pH 4 beträgt für Benzol, Toluol und Xylol 29,45 kJ mol-1, 34,41 kJ mol-1 bzw. 35,58 kJ mol-1, bei pH 10 30,17 kJ mol-1, 35.56 kJ mol-1 bzw. 39,39 kJ mol-1. Die adsorbierte Menge nimmt in der Reihenfolge Benzol 〉 Toluol 〉 Xylol ab.
    Notes: The removal of benzene, toluene and p-xylene (BTX) compounds from aqueous solutions with highly crosslinked cationic starch containing tertiary amine groups was investigated. The adsorption process has found to be initial pH- and initial concentration-dependent, endothermic, and follows the Langmuir isothermal adsorption.The heats of adsorption (ΔH) at initial pH = 4 of benzene, toluene and p-xylene compounds are 29.45 kJ mol-1, 34.41 kJ mol-1, and 35.58 kJ mol-1, respectively, those at initial pH = 10 are 30.17 kJ mol-1, 35.56 kJ mol-1, and 39.39 kJ mol-1, respectively. The order of the amount of adsorbed BTX compounds on the adsorbent is benzene 〉 toluene 〉 p-xylene.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052510110
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    Thermogravimetric and ESR studies of polymer/metal precursors for high-temperature superconductors (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 157-170 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Bi-Sr-Ca-Cu-Komplexverbindungen von Polymethacrylsäure (PMAA) und Kresolnovolaken, die als Precursoren für Hochtemperatursupraleiter (HTSL) eingesetzt werden, sowie deren Cu-Komplexsalze wurden ESR-spektroskopisch und thermogravimetrisch untersucht. In den PMAA-Proben wurden drei verschiedene Cu2+-Spezies nachgewiesen: i) Cu2+-Paare, ii) isolierte Cu2+-Ionen und iii) Cu2+-Cluster. Bei niedrigem Cu-Gehalt der Proben bilden die Cu2+-Paar-Bindungen den Hauptanteil, bei hohem Cu-Gehalt überwiegen die Clusterbindungen. In den Novolakproben wurden nur isolierte Cu2+-Ionen und Cu2+-Cluster nachgewiesen. Die Einführung der Cu-Ionen erniedrigt die thermische Stabilität der Polymeren, der thermische Abbau erfolgt stufenweise. In den PMAA-Proben wird die erste Abbaustufe bei ≈ 220°C durch die Cu2+-Paar-Komplexe verursacht.
    Notes: Bi-Sr-Ca-Cu complexes of poly(methacrylic acid) (PMAA) and cresol novolac, which are precursors for high-temperature superconductors (HTSC) and Cu complexes of those polymers were investigated by ESR spectroscopy and thermogravimetry. In the PMAA samples three different kinds of Cu2+ species were detected: i) Cu2+ pairs, ii) isolated Cu2+ ions and iii) Cu2+ clusters. While Cu2+ pairs are the main species at low Cu concentrations, clusters become dominant at high Cu contents. In the novolac samples Cu2+ was only detected in isolated sites and clusters. The introduction of Cu ions lowered the thermal stability of the polymers and led to a stepwise decomposition. In the PMAA samples the first decomposition step at ≈ 220°C is caused by the Cu2+ pair complexes.
    Additional Material: 6 Ill.
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    Polymerization of 1,3-butadiene with neodymium chloride/2-ethylhexanolate/triethylaluminium catalyst systemIPCL communication No. 325. (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 193-205 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Neodymchlorid-2-ethylhexanolate mit der allgemeinen Formel NdCl3 · nL wurden durch eine Liganden-Austauschreaktion zwischen Neodymchloridisopropanolat (I) und 2-Ethylhexanol (EH) hergestellt. Die Hexanolate NdCl3 · 1,5 EH (II) und NdCl3 · 2,5 EH (III) wurden durch Elementaranalyse und Gravimetrie charakterisiert. Die katalytische Aktivität der Hexanolate bei der Homopolymerisation von 1,3-Butadien in Gegenwart von Triethylaluminium wurde untersucht. Die Verbindung III zeigte eine höhere Aktivität als die Verbindung II. Höhere Katalysator- und Cokatalysatorkonzentrationen sowie eine höhere Temperatur steigerten den Umsatz, wogegen die Viskosität der Produkte abnahm. Mit zunehmender Reaktionszeit erhöhten sich sowohl der Umsatz als auch die Viskosität. Die cis-1,4-Konformation wurde durch die Variation von Temperatur und Cokatalysatorkonzentration beeinflußt. Der gesamte Anteil der cis-1,4-Stuktur lag jedoch in allen Fällen über 99%, während die Produkte nur einen sehr geringen Vinyl-Anteil von 〈1% enthielten. Die Zugabe einer elektronenspendenden Verbindung verringerte den cis- 1,4-Gehalt aber auf 87%.
    Notes: Neodymium chloride 2-ethylhexanolates of the general formula NdCl3 · nL were prepared by ligand exchange reaction between neodymium chloride ispropanolate (I) and 2-ethylhexanol (EH). These hexanolates, NdCl3 · 1.5 EH (II) and NdCl3 · 2.5 EH (III), were characterized by elemental analysis and gravimetry. The catalytic activity of these hexanolates in combination with triethyl aluminium in the homopolymerization of 1,3-butadiene was studied, and the activity was found to be higher with III than II. The conversions increased with increasing the catalyst and co-catalyst concentrations and the temperature, whereas the intrinsic viscosity decreased. The conversions and the intrinsic viscosity decreased. The conversions and the intrinsic viscosity increased with reaction time. The cis-1,4 structure was influenced by variation in temperature and co-catalyst concentration, however, the total cis-1,4 structure was always more than 99% with very low vinyl content (〉1%). Addition of an external electron donor decreased the cis-1,4 content to 87%.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052510117
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    Ideal crosslinked-polymers and their characterization in free-radical monovinyl-divinyl copolymerizationsPoster presented at the “International Symposium on Advanced Network-Polymers, Kansai University” (ISANKU), at Kansai University, Suita, Osaka, Japan, on December 5-6, 1995. (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 240 (1996), S. 275-284 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The critical conditions in which the classical Flory-Stockmayer gelation theory (F-S theory) is applicable to monovinyl-divinyl copolymerizations were pursued in detail. The resulting prepolymers or precursors of ideal crosslinked-polymers were characterized as standard polymers for the discussion of network formation in free-radical monovinyl-divinyl copolymerizations. Methyl methacrylate was copolymerized with a small amount of ethylene dimethacrylate, butylene dimethacrylate or nonapropyleneglycol dimethacrylate in the presence of lauryl mercaptan, a chain transfer agent to reduce the occurrence of a thermodynamic excluded volume effect and intramolecular crosslinking as the primary and secondary factors, respectively, for the greatly delayed gelation in the free-radical monovinyl-divinyl copolymerizations and, moreover, to keep the primary chain length constant by inhibiting a gel effect. The ratio of the actual gel point to the theoretical one reached 1.1, supporting the validity of F-S theory. The resulting prepolymers were subjected to SEC-MALLS analysis to determine the molecular weights, the molecular-weight distributions and the radii of gyration; the correlations of molecular weight vs. elution volume and radius of gyration vs. molecular weight were useful for the characterization of the precursors of ideal network-polymers.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1996.052400126
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    Chemical reactions on polysaccharides, 5Part 4: Chloroacetylated derivatives of dextran, Cellul. Chem. Technol. 26 (1992) 675. Reaction of mesyl chloride with pullulan (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 1-10 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Reaktion von Mesylchlorid mit vernetzten Pullulan-Mikropartikeln wurde untersucht, insbesondere der Einfluß der Reaktionsbedingungen auf das Produktverhältnis Chlordeoxy-/O-Mesylpullulan. In N,N-Dimethylformamid wird vorwiegend Chlordeoxypullulan gebildet, während in Pyridin bei niedrigen Temperaturen der Mesylester das Hauptprodukt ist. In N,N-Dimethylacetamide entstehen Chlordeoxy und Mesylgruppen im Verhältnis 2:1. Durch die Einführung der Chlordeoxy- bzw. Mesylgruppen werden die Mikropartikel hydrophob.
    Notes: The reaction of mesyl chloride with crosslinked pullulan microparticles was investigated, in particular the influence of the reaction conditions on the ratio between the two possible products chlorodeoxy or O-mesyl pullulan. It was found that in N,N-dimethylformamide the preponderent reaction product is chlorodeoxy pullulan, while in pyridine at low temperatures the main product is the mesyl ester of pullulan. In N,N-dimethylacetamide, the substituent groups are both chlorodeoxy and mesyl ones, in about 2:1 ratio. By the introduction of either chlorodeoxy or mesyl groups, the pullulan-crosslinked microparticles become hydrophobic.
    Additional Material: 8 Ill.
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    Structural analysis of poly(4-hydroxybutyl acrylate)-grafted silk fibres (1996)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 241 (1996), S. 41-56 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Poly(4-hydroxybutylacrylat) poly(4-HBA) wurde aus wäßrigem Medium mit Ammoniumpersulfat als Initiator auf Seide (bombyx mori) aufgepfropft. Die Gewichtszunahme stieg proportional mit der Monomerkonzentration im Pfropfsystem. Der Pfropfgrad lag im Bereich von 45 bis 65%. Die Feuchtigkeitsaufnahme nahm bei einer Gewichtszunahme von 〉10% stark ab. Die mechanischen Eigenschaften der Seidenfasern zeigten mit steigender Gewichtszunahme keine wesentliche Änderung. Doppelbrechung und isotroper Brechungsindex nahmen bis zu einer Gewichtszunahme von 35% ab und blieben dann unverändert. Röntgenbeugungsdiagramme zeigten, daß die kristalline Struktur durch die Pfropfbehandlung nicht modifiziert wird. Kalorimetrische (DSC), thermomechanische (TMA) und thermogravimetrische (TG) Analysen ergaben, daß das thermische Verhalten der poly(4-HBA)-gepfropften Seidenfasern nur leicht verändert wird. Die zur Bestimmung des dynamisch-mechanischen Verhaltens der Seidenfasern durchgeführten DMA-Messungen zeigten eine Verschiebung der E′- und E″-Modulspitzen zu niedrigeren Temperaturen mit steigender Gewichtszunahme. Ablagerungen auf der Faseroberfläche der bei einem hohen Monomer/Seide-Verhältnis (〉50%) gepfropften Seide wurden mit Rasterelektronenmikroskopie nachgewiesen.
    Notes: Poly(4-hydroxybutyl acrylate) poly(4-HBA) was graft-copolymerized onto silk fibres (bombyx mori) in aqueous medium with ammonium persulfate as initiator. The weight gain increased with increasing concentration of monomer in the grafting system. The grafting efficiency ranged from 45 to 65%. Equilibrium moisture regain decreased sharply beyond 10% weight gain. The tensile properties of the silk fibres did not change significantly as a function of the increasing weight gain. Birefringence and isotropic refractive index decreased until 35% weight gain and then remained unchanged. The X-ray diffraction patterns showed that the crystalline structure was not affected by grafting. Differential scanning calorimetry (DSC), thermomechanical (TMA), and thermogravimetric (TG) measurements showed that poly(4-HBA)-grafted silk fibres underwent only slight changes in the thermal behaviour. The dynamic mechanical measurements (DMA) exhibited a downward shift of both the storage (E′) and loss modulus peak (E″) with increasing weight gain. Scanning electron microscopy (SEM) observations showed the presence of some deposits adhering to the surface of silk fibres grafted at high monomer/silk ratio (〉50%).
    Additional Material: 7 Ill.
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    The effects of desolvation methods of the recrystallized MgCl2-alcohol adduct on catalyst characteristics and the bulk density of polyethylene (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 17-25 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: MgCl2-Träger für einen Ethylenpolymerisationskatalysator wurden mit Hilfe der Rekristallationsmethode hergestellt, wobei Methanol als Lösungsmittel diente. Der Einfluß verschiedener Lösungsmethoden des rekristallisierten MgCl2-Alkohol-Adduktes auf die morphologischen Charakteristika der Katalysatoren wurde untersucht. Die Lösungsmethode beeinflußt die Eigenschaften der Katalysatoren beträchtlich. Die dargestellten Katalysatoren wiesen unterschiedliche Ti/Mg-Verhältnisse auf, sowohl was die Oberfläche als auch die gesamten Katalysator-Partikel betrifft. Betrachtet man die Ti-Verteilung und Aktivitätsprofile, dann erweisen sich nicht nur die Polymerisationsbedingungen, sondern auch die Ti-Verteilung auf dem Katalysator als wichtige Faktoren, welche die Dichte der Polymeren beeinflussen.
    Notes: The MgCl2 supports for an ethylene polymerization catalyst were prepared by the recrystallization method using methanol as a solvent. The effects of different desolvation methods of the recrystallized MgCl2-alcohol adduct on the morphological characteristics of the catalysts were examined. The desolvation method greatly affects the characteristics of the catalyst. The prepared catalysts had different Ti/Mg ratios with respect to both surface content and entire catalyst particles. Considering Ti distribution and activity profiles, not only the polymerization conditions but also the Ti distribution on the catalyst appear to be an important factor which affects the bulk density of the polymers.
    Additional Material: 3 Ill.
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    Synthesis of aromatic poly(ether ketone)s with ferrocene units in the main chain (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 89-97 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Aromatische Poly(etherketon)e mit Ferrocen-Einheiten in der Hauptkette wurden durch direkte Polykondensation von 1,1′-Ferrocendicarbonsäure mit Diphenylether oder 1,4-Diphenoxybenzol hergestellt. Als Katalysatoren wurden Trifluormethansulfonsäure, Methansulfonsäure/P2O5 (Eatons Reagens) oder Trifluormethansulfonsäure/P2O5 verwendet. Polykondensationen bei Raumtemperatur für 24 h ergaben Poly(arylenetherketon)e mit Grenzviskositäten bis zu 40 mL g-1. Die Monoacylierung von Diphenylether mit Ferrocencarbonsäure wurde im Hinblick auf die Effektivität von Eatons Reagens als Katalysator und Lösungsmittel eingehender untersucht.
    Notes: Aromatic poly(ether ketone)s with ferrocene units in the main chain were prepared by direct polycondensation of 1,1′-ferrocenedicarboxylic acid with diphenyl ether or 1,4-diphenoxybenzene using various catalysts such as trifluoromethanesulfonic acid (triflic acid), a combination of methanesulfonic acid/P2O5 (Eaton's reagent) or a combination of triflic acid/P2O5. Polycondensations at room temperature for 24 h gave poly(arylene ether ketone)s with inherent viscosities up to 40 mL g-1. Monoacylation of diphenyl ether with ferrocenecarboxylic acid was studied in detail in order to show the efficiency of polymer formation employing Eaton's reagent as catalyst and solvent.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052530107
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    Mechanical and structural characteristics of phenolphthalein poly(ether sulfone)/ultra-high molecular weight polyethylene blends (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 73-80 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die mechanischen und strukturellen Eigenschaften von Blends aus Phenolphthalein-Polyethersulfon und ultrahochmolekularem Polyethylen (UHMWPE) wurden anhand von Zug- und Biegeversuchen, Raster- und Transmissionselektronenmikroskopie untersucht. Die Zugabe einer geringen Menge UHMWPE (2 Gew.-%) führt zu einer Verstärkung der PES-C-Matrix. Höhere UHMWPE-Konzentrationen verschlechtern die mechanischen Eigenschaften. Die Strukturuntersuchungen zeigen, daß die Blends im gesamten Zusammensetzungsbereich mehrphasig sind. Bei geringen UHMWPE-Konzentrationen ist die UHMWPE-Phase gleichmäßig verteilt und entlang der Fließrichtung orientiert, was mit der starken Grenzflächenadhäsion zur Verbesserung des mechanischen Verhaltens beiträgt. Mit steigender UHMWPE-Konzentration nimmt die Domänengröß der UHMWPE-Phase zu.
    Notes: Mechanical and structural properties of blends of phenolphthalein poly(ether sulfone) (PES-C) with ultra-high molecular weight polyethylene (UHMWPE) were investigated using tensile and bending testing, scanning electron microscopy and transition electron microscopy. The incorporation of minor amounts of UHMWPE (2 wt.-%) into PES-C has a reinforcement effect. With higher concentrations of UHMWPE, the mechanical properties decrease gradually. Structural studies demonstrated that the blends are multiphasic in the whole composition range. The minor UHMWPE, dispersed uniformly and oriented along the flow direction, as well as the strong interfacial adhesion contribute to the increase of the mechanical performance of the blends. The domain size of the UHMWPE phase was found to increase with the increase of its concentration.
    Additional Material: 6 Ill.
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    Redox copolymer with N-bromosulfonamide groups for the decomposition of cyanide ions in dilute aqueous solutions (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 117-130 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein Redoxcopolymeres, ein makroporöses Poly(Styrol-co-Divinylbenzol) (S/DVB)-Harz mit N-Bromsulfonamidgruppen, wurde angewandt, um Cyanide aus wäßrigen Lösungen zu entfernen. Dieses Harz enthält aktives Brom in den funktionellen Gruppen (1.86 mmol g-1, 3.72 meq g-1) und weist Oxidationseigenschaften auf. Es wurde sowohl in statischen als auch in dynamischen Systemen für die Oxidation von Cyanidionen zu nichttoxischen Verbindungen angewandt. Die Reaktionen wurden in wäßrigen Lösungen mit 26-2600 mg L-1 CN- bei unterschiedlichen pH-Werten durchgeführt. Die Ergebnisse zeigten, daß dieses Harz die Cyanide leicht zu Cyanaten oxidiert, die ca. 1000 mal weniger toxisch sind. Bei Kontakt mit dem Harz fiel die Cyanidkonzentration in den Lösungen unter 0.05 mg L-1 CN-. Die —SO2NBrNa-Gruppen gingen dabei in —SO2NH2-Gruppen über. Diese konnten wiederum mit Natriumhypochlorit- und Natriumbromid-Lösungen reaktiviert werden. Es wurde auch eine Alternative zu der Cyanidionenoxidation mit N-Bromsulfonamid-Harz untersucht, indem ein analoges N-Chlorsulfonamid-Harz in Gengenwart von katalytischen Mengen von Bromiden angewandt wurde.
    Notes: A redox copolymer, macroporous poly(styrene-co-divinylbenzene) (S/DVB) resin having N-bromosulfonamide groups, was used for removal of cyanide ions from aqueous solutions. This resin contains active bromine in functional groups (1.86 mmol g-1, i. e. 3.72 meq g-1) and shows oxidative properties. It was employed in static and flow system for oxidation of cyanide ions to non-toxic compounds. The reactions were carried out in aqueous media containing 26-2600 mg L-1 CN- at different pH values. The data showed that the resin having active bromine easily oxidized cyanides, forming cyanates being 1000-times less toxic than cyanides. In contact with the resin the concentration of cyanides in tested solutions dropped below 0.05 mg L-1 CN-. During the oxidation processes the —SO2NBrNa groups transform to —SO2NH2 groups. They can be reactivated by use of sodium hypochlorite and bromide solutions. As an alternative to oxidation of cyanides by N-bromosulfonamide resin, the oxidation of these ions by N-chlorosulfonamide resin with addition of a small amount of bromides was examined.
    Additional Material: 3 Ill.
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    Mitteilungen/Announcements (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 251 (1997), S. 207-208 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: No Abstract
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1997.052510118
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    Hydrolytic and thermal stability of novel polyurethane elastomers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 33-43 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Novel Polyester glycols with alkyl side groups were used for the improvement of thermal stability and hydrolytic stability of polyester urethane elastomers. The novel polyester glycols used are poly( β -methyl- δ -valerolactone)glycol (PMVL), poly(3-methyl pentamethylene adipate) glycol (PMPA), poly(nonamethylene-co-2-methyl octamcthylene carbonate) gycol (PNCO). A mixture of PNCO and poly(dimethyl siloxane)gycol (PNCO/PDMS) was also used. Polyurethane network elastomers were prepared from 4,4′-diphenylmethane diisocyanate (or 2,4-tolylene diisocyanate), and a mixture of 1,4-butane diol and trimethylol propane by a prepolymer method. Mechanical properties, Tg, thermal stability, and hydrolytic stability were measured. Morphology were also measured by means of polarizing microscopy, dynamic viscoelastometer, and ESR. The properties of novel polyurethane elastomers have good mechanical properties comparable to those of the general purpose polyester urethanes, and better thermal and hydrolytic stability than PTMG-based polyurethane. These polyurethane elastomers were exposed in out door during 2 year in Nagasaki, JAPAN. The novel polyurethane clastomers held alomost constant values for gel fraction, swelling ratio, relative modulus during 12 months, while poly(oxytetramethylene oxide)-based polyurethane as a control decreased the these values. Relationship of degradation behaviors with chemical structure and morphology were discussed.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520103
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    Oxidizability of lactams and lactam-based polyamidesDedicated to Dr Jan Šebenda on the occasion of his 70th birthday (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 139-151 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the chain oxidation of N-alkylamides with molecular oxygen, propagation is the ratedetermining step under conditions when the oxidation rate is independent of oxygen pressure. The oxidizability of lactams and lactam-based polyamides correlates with the energy of the formation of N-alkylamide radical by abstraction of hydrogen from the methylene group adjacent to nitrogen. While for lactams this energy depends on the number of carbons in the lactam ring, for N-alkylamides and polylactams such dependence is not observed.
    Additional Material: 1 Tab.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520110
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    Use of EPR to image nitroxyl radicals in hals stabilized polymers (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 179-193 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: An X-band EPR-Imaging apparatus which allowed us to determine the distribution of nitroxyl radicals within solid samples of polymeric materials containing hindered amine stabilizers, is described. It is shown that EPR Imaging represents a powerful tool for investigating the growth and decay of nitroxyls formed in polymers irradiated under air for long periods. Since the variations of the radical concentration can be monitored both in time and in the space, this technique provides valuable information not easily attainable by means of other methods.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520113
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    Photo-oxidation mechanisms of poly(2,6-dimethyl-1,4-phenylene oxide). (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 237-256 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A re-examination of the photo-oxidation mechanism of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) at both long and short irradiation wavelengths under accelerated conditions is reported. The formation rate of poly-2,6-dimethylphenoxy (PDMP) radicals, have been observed by esr spectroscopy, while benzylic-type radicals have been detected by spin trapping experiments using nitrosodurene under UV irradiation conditions. The changes of FTIR spectra obtained under accelerated photo-oxidative conditions show the formation of primary oxidation products such as aromatic aldehydes and quinones. The direct formation of radical cations and superoxide anions by a photo-induced electron-transfer reaction is suggested under our conditions. In addition, some results on the of photo-oxidation PPO/PS blends as a function of polystyrene tacticity are also reported. In the case of syndiotactic polystyrene the blend photostability shows some differences in comparison with the blend containing atactic polystyrene. This effect has been ascribed to the absence of excimers in syndiotactic polystyrene which are not revealed by fluorescence measurements. Finally, the chemical modification of PPO with bromine gave a bromomethylated PPO with different amounts of CH2 Br groups, which has been used for further substitution reactions with alkoxy sodium salts of 4-hydroxy-2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and 4-hydroxy-1,2,2,6,6-pentamethylpiperidine (PMPP). The accelerated photo-oxidation of a modified copolymer PPO-PMPP containing a 60% PMPP moieties as side groups and its blends with pure PPO has been followed by FTIR and esr spectroscopies. Some comparisons with a commercially available hindered amine light stabilizers (HALS) and a modified copolymer PPO-PMPP are also reported under the same photo-oxidative conditions.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/apmc.1997.052520116
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    Zähigkeit und Relaxationsverhalten von Polymethylmethacrylat, Polystyrol und Polycarbonat (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 27-49 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: For innovative applications of plastics, which take advantage of special properties of polymeric materials, comprehensive understanding on strengthening and toughening mechanisms is required. The temperature-dependent mechanical behaviour of PMMA, PS and PC under dynamic loading conditions were investigated by means of an instrumented Charpy impact tester. The elastic-plastic fracture mechanics parameters, the energy-determined J-integral, and the deformation-determined crack opening displacement, δ, enable to do structure-related quantification of micromechanical processes. The J-integral values showed a maximum, resulting from an energy-dissipative process. The maximum values for PMMA occurred at 50°C and for PC at 40°C , which is related to the secondary(β) relaxation as evaluated from the frequency dependence of the mechanical loss factor. The 0-relaxation initiated shear deformation mechanisms, which led to a local increase of toughness. In polycarbonate, toughness is strongly increased due to a stress-induced shear flow process at temperatures higher than -25°C. Correlations between morphology and toughness can be derived with the help of optical investigations of stable crack propagation on fracture surfaces.
    Notes: Innovative Kunststoffanwendungen, die die speziellen Eigenschaften polymerer Werkstoffe gezielt ausnutzen, erfordern vertiefte Kenntnisse über festigkeits- und zähigkeitsbestimmende Mechanismen. Das sich in Abhängigkeit von der Temperatur ändernde Werkstoffverhalten von PMMA, PS und PC wurde bei dynamischer Beanspruchung mittels instrumentierter Kerbschlagbiegeprüfung bestimmt. Mit der verformungsbestimmten Rißöffnungsverschiebung δ und dem energiebestimmten J-Integral stehen Kenngrößen der Fließbruchmechanik zur Verfügung, die eine strukturbezogene Quantifizierung der temperaturabhängigen mikromechanischen Prozesse erlauben. Die J-Integralwerte zeigen für PMMA bei 50°C und für PC bei -60°C ein durch einen energiedissipativen Prozeß verursachtes Maximum. Dieses Maximum steht, wie sich aus der Interpretation der Frequenzabhängigkeit des mechanischen Verlustfaktors ergibt, mit der Neben(β)-Relaxation in Beziehung. Dabei initiiert die β-Relaxation Scherdeformationsmechanismen, die ihrerseits die lokale Zähigkeitserhöhung bewirken. Ab -25°C führt für PC ein spannungsinduzierter Scherfließprozeß zu einer erheblichen Zähigkeitssteigerung. Durch die Einbeziehung lichtmikroskopischer Untersuchungen des stabilen Rißfortschritts auf der Bruchfläche können Morphologie-Zähigkeits-Korrelationen abgeleitet werden.
    Additional Material: 16 Ill.
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    Thermostable block copolymers, 2Part 1 cf. 16.. Preparation and characterization of soluble blockcopolyimides (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 71-88 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polyamidimid-Polyimid-Blockcopolymeren (PAI-PI-BCPs) wurde durch Polykondensation von PAI-Blöcken mit Amino-Endgruppen und PI-Blöcken mit Anhydrid-Endgruppen hergestellt. Zur Synthese der Blöcke mit Molekulargewichten im Bereich von ca. 2000 bis 15000 wurden nur technisch leicht zugängliche Monomere, wie Trimellitsäureanhydridchlorid, Benzophenontetracarbonsäuredianhydrid, 4,4′-Diaminodiphenylmethan, 2,4-Toluylendiamin und 4,4′-Diaminodiphenylsulfon eingesetzt. Dabei zeigte sich, daß durch den blockartigen Aufbau die Löslichkeit-und damit die Verarbeitbarkeit-im Vergleich zu den reinen, unlöslichen Polyimiden wesentlich verbessert werden konnte, bei nahezu gleichbleibender Thermostabilität. So wurden BCPs mit guten mechanischen Eigenschaften, Thermostabilitäten bis ca. 480°C (Thermogravimetrie, 5% Gewichtsverlust) und guten Löslichkeiten in Dimethylacetamid und anderen polaren aprotischen Lösungsmitteln erhalten.
    Notes: New poly(amide-imide)-poly(imide) block copolymers (PAI-PI-BCPs) were prepared by polycondensation of amino-terminated PAI-blocks with anhydride-terminated PI-blocks. For the syntheses of the blocks with molecular weights from 2000 to 15000 only commercially available monomers were used, e.g. trimellitic acid anhydride chloride, benzophenone tetracarboxylic acid dianhydride, 4,4′-diaminodiphenylmethane, 2,4-toluenediamine and 4,4′-diaminodiphenylsulfone. The BCPs were shown to have better solubility compared to the pure, insoluble PIs with only minor decrease of the thermostability. Thus, BCPs with good mechanical properties, thermostabilities up to 480°C (thermogravimetric analysis, 5% weight loss) and good solubility in dimethylacetamide and other polar aprotic solvents were obtained.
    Additional Material: 4 Tab.
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    Block and graft copolymers with polysiloxane and poly(N-acyliminoethylene) sequences (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 139-149 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Eine Reihe von Polysiloxan/Poly(N-acetyliminoethylen)-(PSiO/PNAI)-Block- und -Pfropfcopolymeren wurde durch Polymerisation von 2-Methyl-2-oxazolin (MeOZO) mit funktionellen Polysiloxan-Prepolymeren als Initiatoren synthetisiert. Die Copolymeren wurden mit IR- und 1H NMR-Spektroskopie sowie Elementaranalyse, Differentialkalorimetrie und Thermogravimetrie charakterisiert. Der Einbau sowohl von hydrophoben als auch von hydrophilen Sequenzen verleiht den Polymeren amphiphile Eigenschaften. Ihre Eigenschaften in Lösung und als Feststoffe lassen die Produkte für Anwendungen als nichtionische Emulgatoren, Oberflächenmodifikatoren, Gele, usw. geeignet erscheinen.
    Notes: A series of polysiloxane/poly(N-acetyliminoethylene) (PSiO/PNAI) block and graft copolymers were synthesized by the initiation of 2-methyl-2-oxazoline (Me-OZO) polymerization with functional polysiloxane prepolymers. The copolymerization products were characterized by IR- and 1H NMR spectroscopy, elemental analysis, DSC and thermogravimetry. The insertion of both hydrophobic and hydrophilic sequences in the macromolecular structure induces a behavior characteristic of amphiphilic compounds. Their solution and solid state behavior evidenced peculiarities which make them able to act as nonionic emulsifiers, surface modifiers, gels, etc.
    Additional Material: 4 Ill.
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    The state of water in styrene-grafted and sulfonated poly(vinylidene fluoride) membranes (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 151-167 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Der Zustand von Wasser in Protonenaustausch-Membranen, hergestellt durch Pfropfen von Styrol auf Polyvinylidenfluorid-Filme (PVDF-g-PS) mittels Elektronenstrahlen und anschließendes Sulfonieren (PVDF-g-PSSA), wurde mittels Differentialkalorimetrie (DSC), Raman-Spektroskopie und Rontgen-Diffraktion (SAXS) ermittelt. Die Raman-Untersuchungen zeigten, daß einzelne Wassermolekule durch hydrophobe Wechselwirkungen an die Polymerketten gebunden sind. Die DSC-Untersuchungen zeigten, daß Wasser in den Membranen in drei verschiedenen Umgebungen vorliegt: nicht gefrierendes ionisch gebundenes Wasser, gefrierendes freies Wasser und gefrierendes gebundenes Wasser. Die Menge an nicht gefrierendem Wasser betragt unabhangig vom Pfropfungsgrad etwa 10 H2O/SO3H (mol/mol). Die Menge an gefrierendem Wasser ist stark vom Pfropfungsgrad abhangig. Oberhalb eines Pfropfungsgrades von 50% werden Werte von 40 H20/S03H (mol/mol) erreicht. Die Leitfahigkeit von nur nicht gefrierendes Wasser enthaltenden Membranen ist gering, d. h., das ionisch gebundene Wasser kann nicht allein die fur den Transport von Protonen und Wasser notwendigen Kanale bilden. Die SAXS Untersuchungen zeigten, daß Wasser/Sulfonsaure-Cluster in Membranen aus hydratisiertem PVDF-g-PSSA mit einem Bragg-Abstand von 25 Å gebildet werden. Diese Cluster formen die Kanale fur den Ionentransport und die Leitfähigkeit.
    Notes: The state of water in proton exchange membranes prepared by pre-irradiation (electron beam, 100 kGy) grafting of styrene onto poly(vinylidene fluoride) films (PVDF-g-PS), followed by sulfonation (PVDF-g-PSSA), has been studied with thermal analysis, Raman spectroscopy and small angle X-ray diffraction (SAXS). Raman spectra show that, in addition to free liquid water in the membranes, single water molecules are weakly bound to the polymer backbone. Thermal analysis shows that there are three types of water molecules in the membrane; non-freezable water associated with the ionic sites, freezable free water, and freezable bound water. The amount of non-freezable water is around 10 H2O/SO3H (mol/mol), and is independent of the degree of grafting (d.o.g.). The amount of freezable water is strongly dependent on the d.o.g. as long as the grafting has not penetrated the whole of the film, and reaches a value of around 40 H2O/SO3H (mol/mol) above a d.o.g. of 50%. The conductivity of membranes containing only the non-freezable water is low, i. e. the ionically bound water alone does not form the domains necessary for proton and water transport. SAXS measurements show that water/sulfonic acid clusters in hydrated PVDF-g-PSSA membranes with a Bragg distance of 25 Å are formed; these form the ion conducting channels in the membrane.
    Additional Material: 9 Ill.
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    MITTEILUNGEN/ANNOUNCEMENTS (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 211-211 
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    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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    Tensile and flexural behavior of polypropene sheets with different crystallinities of surface layer (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 253 (1997), S. 201-210 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die Zug- und Biegemoduli von preßgeformten Polypropen-Probekörpern mit unterschiedlichen Oberflächenkristallinitäten wurden basierend auf der Annahme eines Schicht-Verbund-Modells untersucht. Es zeigte sich, daß die Spannungs-Dehnungs-Kurven der Zugversuche und die Werte der Biegeablenkung im wesentlichen von der Oberfächenkristallinität abhängen, jedoch erwiesen sich die Bruchspannungen als von der Oberflächenkristallinität unabhängig. Es wird angenommen, daß das beobachtete Zug- und Biegeverhalten der Proben auf der Grundlage eines Schicht-Verbund-Modells, bei dem eine massive, starre Platte zwischen zwei weichen Schichten eingebettet ist, charakterisiert werden kann.
    Notes: The tensile and flexural moduli of the compression-molded sheets of polypropene with different surface layer crystallinity were investigated based on a layered composite model. It was found that the tensile stress-strain curve and flexural deflection depended largely on the surface layer crystallinity, but the ultimate strain-at-break values were independent of the surface layer crystallinity. It is suggested that the tensile and flexural behavior can be characterized using a layered composite model in which a bulk plate was sandwiched between two surface layers.
    Additional Material: 4 Ill.
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    The role of charge transfer complexes in the photodegradation of polyolefins (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 45-54 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Addition of HALS-stabilisers, the cut-off wavelength of the light source, the temperature and the oxygen pressure have an influence on the UV-degradation mechanism of polyolefins. All these parameters influences the conversion of oxygen into polymeric carbonyls. The results are explained assuming that the initiation of the UV-degradation of pololefins is due to substrate-oxygen charge transfer complexes (CTCs).
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    Fracture behavior of exposed HDPE specimens with an embrittled layer due to UV-exposure (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 69-88 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The applicability of fracture mechanics was studied on UV-exposed HDPE Charpy specimens. The failure distribution of the stress at failure measured in three-points bending tests showed a bifurcation in failure processes. At high stresses yielding occurs, resulting in large strain at failures. At lower stresses crack propagation causes low strain at failures. Due to the bifurcation in failure processes the ductile-brittle transition temperature of exposed specimens is hard to determine.Specimens notched after exposure showed a decrease in the critical stress intensity values. The effective notch depth of exposed specimens was found to be larger than the thickness of the oxidized layer measured by FT-IR and density measurements.
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    Deactivation processes of 2-hydroxyphenyl-1,3,5-triazines  -  polymeric and monomeric UV absorbers of the benzotriazole and triazine class (1997)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 252 (1997), S. 119-138 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In the 2-hydroxyphenyl-1,3,5-triazines, the intramolecular hydrogen bond is stronger than in the corresponding 2-hydroxyphenylbenzotriazoles. Compounds with only one aryl group in the 2-hydroxyphenyl-1,3,5-triazine series show proton-transferred fluorescence with large Stokes shift and high quantum yield. No such fluorescence is observed, in contrast, for compunds with three aryi groups bearing no electrondonating groups on the aryl moieties. When the hydrogen atom of the intramolecular hydrogen bond is replaced by CH3, the respective derivative shows fluorescence with a normal Stokes shift.Various copolymers of MA-TIN 1 (2-[2-hydroxy-3-tert.-butyl-5-(O-[2-hydroxy-3-(2-methylpropenoyloxy)propyl]-2-carbonyloxyethyl)phenyl]benzotriazole), and MA-TZ 1 (2,4-Bis(2,4-dimethyl-phenyl)-6-[2-hydroxy-4-(2-hydroxy-3-[2-methylpropenoyloxy])propoxyphenyl]-1,3,5-triazine) with styrene, methyl methacrylate, and methacrylic acid have been synthesized by radical polymerization. The absorption spectra in the longwavelength UV region appear unchanged compared to those of the monomeric UV absorbers indicating that the stabilizer chromophores are conserved intact in the polymer. Both the monomeric and the polymeric stabilizers exhibit a strongly Stokesshifted, temperature-dependent, low-quantum-yield, proton-transferred fluorescence. This may be taken as evidence that the intramolecular hydrogen bond, which is essential for the photostability of this type of UV absorber, remains intact also in the copolymers. Activation energies of the radiationless deactivation process can be evaluated from the temperature dependence of this fluorescence. These energies lie between 4 and 5 kJ/mol for most of the benzotriazole and triazine stabilizers investigated.Fluorescence-decay measurements with crystalline MA-TIN 1 at different temperatures reveal a close correspondence of the temperature dependence between decay times and relative quantum yields. The radiationless process is thence concluded to originate from the proton-transferred level S1'. The decay time at room temperature is estimated at 70 ps, close to the value for crystalline TIN P (2-(2-hydroxy-5-methylphenyl)benzotriazole). The proton-transferred fluorescence of MA-TIN 1 exhibits a biexponential decay profile whereas solid TIN P, in contrast, displays only one single lifetime.
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    Statistical mechanics of noncovalent bonds in polyamino acids. IX. The two-state theory of protein denaturationThis work was supported by a research grant (AI-01473) from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, U. S. Public Health Service, and by a research grant (GB-2238) from the National Science Foundation. (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 401-419 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The two-state theory of protein denaturation, in which it is assumed that a protein exists as two species, native and denatured, is examined by three approaches in this paper. First, the point is made that denaturation of an isolated molecule involves a continuous shift in the probabilities of occurrence of many states generated by the partition function for the protein. It is argued that the maximum term approximation does not lead to a two-state mechanism of denaturation, and that the extent of cooperation implied by the two-state theory should give very much sharper transitions than are actually found in proteins. Second, the two-state theory is applied to the various model systems treated in this series of papers, and is found to be inadequate. Since the detailed behaviour of the models is known, it is possible to deduce the effect of the incorrect application of the two-state theory to a system that “denatures” by gradual unwinding. This exercise is useful when, thirdly, we examine experimental data that seem to depart radically from a two-state interpretation. We conclude that a mechanism of gradual unwinding is the most generally valid assumption, and that the two-state theory has no theoretical or experimental support.
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    Band-forming centerpieces for the analytical ultracentrifuge (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 481-489 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Three types of band-forming centerpieces useful in band centrifugation in the analytical ultracentrifuge are described. The mode of filling and the advantages and disadvantages of each type are discussed.
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  • 156
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    Physical properties of periodate-oxidized amylose: Aggregation of oxidized amylose in aqueous solutions (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 497-508 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of periodate-oxidized amylose to form aggregates in aqueous solution was studied by sedimentation, light scattering, and viscosity analyses. Ultracentrifuge schlieren patterns show that aggregation can be appreciable at pH 3.0 and 1.0. The hydroxyl ion-catalyzed degradation of the oxidized amylose is faster at pH 3.0 than at pH 1.0. Viscosity and sedimentation analyses conducted at pH 3.0 show that a minimum in the degree of aggregation of the oxidized molecules is obtained at 15-25% oxidation. Solubulity studies and x-ray diffraction patterns on retrograded amylose show that maximum solubility of the retrograded amylose is obtained by oxidizing to the extent of 25-35%. It was therefore concluded that in the general range of 20-30% periodate oxidation, the oxidized amylose has a minimum ability to form intermolecular hydrogen bonds. Outside of this range, oxidized amylose readily forms aggregates in aqueous solutions.
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  • 157
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    Heat of the reaction forming the three-stranded poly (A + 2U) complex (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 491-496 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Calorimetric measurements of the heat of the addition of the second strand of poly U to poly (A + 2U) to form the three-stranded poly (A + 2U) complex in 0.1M and 0.5M NaCl at 24 and 37°C. are reported. A value of ΔH = -3800 cal./mole of poly (A + 2U) formed was found to be fairly insensitive to the experimental conditions employed. The heat of the addition of the third strand to the preformed poly (A + U) helix is considerably less exothermic than the heat of reaction between poly A and poly U to form poly (A + U). The insensitivity of the heat of addition of the third strand (poly U) to changes in salt concentration and temperature lends qualitative support to the earlier hypothesis that the major portion of the variation of the ΔH of the poly A and poly U reaction with experimental conditions arises from differences in the conformation of poly A. Combining the information obtained in this study for the ΔH of the reaction forming poly (A + 2U) with data for the ΔH of the formation of poly (A + U) indicates that the conversion of poly (A + U) to poly (A + 2U) is opposed by an enthalpy change which increases with temperature. Extrapolation of these values to 52°C. where poly (A + U) is transformed to poly (A + 2U) in 0.5M NaCl leads to a value of ΔH = +3800 cal./mole (A + 2U) formed and ΔS = 11.5 cal./mole of (A + 2U) formed. It is concluded from the calorimetric data that the driving force for the poly (A + U) to poly (A + 2U) conversion reaction is the favorable entropy change.
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    Masthead (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965) 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Interaction between proteins and salt solutions. III. Effect of salt type and concentration on the shrinkage temperature (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 461-480 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The effect of salt type and concentration on the transformation of an oriented crystalline collagen tendon into a crosslinked network under conditions of equilibrium swelling was investigated. Our main observations are the following. The degree of swelling of crystalline tendons increases at low salt concentration Cs, and decreases at higher Cs for a wide variety of salts. The observation is not reconcilable with swelling taking place in interfibrillar spaces or structural voids. Within the tropocollagen units and at their ends, regions of reduced organization are postulated (as suggested by Bear and by Schmitt) which are able to interact with the diluent in the amorphous-like manner. At least four different factors should be considered in assessing the role of salt and salt concentration on the shrinkage temperature Ts under isoelectric conditions. They are: (1) specific effects, (2) diluent effects, (3) crosslinking effects, and (4) nonequilibrium effects. The diluent effects are correlated with the salting-in-salting-out power of the ions which was characterized in Part I of this series. Smaller amounts of diluents are generally available to the tendon when the salt has a higher salting-out power, and this corresponds to higher shrinkage temperatures, other conditions being the same. The crosslinking effect raises Ts due to a reduction of the diluent content and, probably for p-benzoquinone and formaldehyde, also to a reduction of the conformational entropy in the molten state. Nonequilibrium effects arise from the fact that shrinkage and recrystallization are kinetically hindered when the tendon is highly deswollen in strong salting-out solutions, or when the salt has a crosslinking power. The specific effect is the only effect which is not related to the amount of diluent present in the tendon. Its origin is less clear. For anions such as Cl- and SCN-, it is possibly related to an ability of the ion to prevent intersegmental hydrogen bonding and water carbonyl bridges. The competition of several of the above effects for a given salt solution makes possible various types of dependence of Ts upon Cs: Ts may either continuously decrease or continuously increase with increasing Cs, or it may go through a minimum. In absence of salt, the cooperative character of the transition at the pH at which maximum swelling occurs appears extremely reduced. The large swelling maintains the tendon in the elongated state and this simulates a continuous decrease of Ts on lowering pH. In presence of small quantities of salt, which reduce swelling, the transition is sharp and Ts is decreased with pH up to pH 2, when maximum swelling occurs, and then reincreases on further lowering of the pH. The dependence of Ts upon Cs is more complex than under isoelectric conditions. There is generally an increase of Ts with Cs which is equivalent to an increase of the denaturation temperature with Cs for helical polyelectrolytes in solution. At higher salt concentrations, however, Ts may decrease again, and possibly increase again at still higher salt concentrations, depending upon the effect of the salt solution in the isoelectric zone.
    Additional Material: 11 Ill.
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    Statistical mechanics of noncovalent bonds in polyamino acids. I. Hydrogen bonding of solutes in water, and the binding of water to polypeptidesThis work was supported by a research grant (AI-01473) from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, U. S. Public Health Service, and by a research grant (GB-2238) from the National Science Foundation. (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 275-282 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: By using the Nemethy-Scheraga theory of water structure, a calculation was made of the energy changes for the rupture of a DH…A solute-solute hydrogen bond in water. A partition function was also obtained for the binding of water and other solutes to the DH and A groups in the special case where these are the NH and CO groups of a random coil polypeptide chain. In subsequent papers of this series, these calculated quantities will be used in a statistical mechanical treatment of the helix-coil transition for polypeptides in water.
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    Statistical mechanics of noncovalent bonds in polyamino acids. III. Interhelical hydrophobic bonds in short chainsThis work was supported by a research agent (AI-01473) from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, U.S. Public Health Service, and by a research grant (GB-2238) from the National Science Foundation. (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 305-313 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A partition function is derived for a simple model of interacting helices in a short (20 residues) chain of poly-L-alanine. It is found that interhelical hydrophobic bonds effect a marked stabilization of helical forms, and give rise to a sharp transition of the type found in many proteins.
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  • 162
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    Electric properties of macromolecules. IX. Dipole moment, polarizability, and optical anisotropy factor of collagen in solution from electric birefringence (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 499-507 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electric birefringence of collagen solutions has been measured over a wide range of field strength with the pulse technique. The soluble collagen was from rat tail tendon. The solvent used was dilute acetic acid. Very pronounced saturation of the electric birefringence was observed, permitting calculation of the optical anisotropy factor. The Kerr constant was determined by extrapolation to zero field strength. From the dependence on field strength of the birefringence, the permanent dipole moment and the anisotropy of polarizability were separately determined. The contribution of the former to the Kerr constant was found to be twice as large as that of the latter. The same conclusion was obtained from the initial slope of the rise curves of the birefringence at low fields. The permanent dipole moment was 1.5 × 104 Debye, and the anisotropy of polarizability was about 3 × 10-15 cm.3. The magnitude of the latter indicates that the ion atmosphere polarization is important. Effects of added salt and thermal denaturation on the electric birefringence were explored.
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  • 163
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    Solvent effects in N-carboxyanhydride (NCA) polymerization initiated by strong base type initiators (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 595-599 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The γ-benzyl-L-glutamate N-carboxyanhydride (NCA) polymerization initialed by diisopropylamine was studied in dimethylformamide (DMF)-dioxane mixtures of different compositions. It was found that the shape of the conversion versus time plots and the molecular weights of the polymers depend on the solvent composition. Auto-catalysis is present only when dioxane predominates in the solvent mixtures. Moreover, the molecular weight of the final polymer depends strongly on the precipitation conditions when the polymerization is carried out in DMF.
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    Crosslinked synthetic polypeptides. I. Preparation and characterization of crosslinked poly Glu51-Lys33Tyr16 and of poly Glu52Lys33Tyr15 no. 3A preliminary report of this work has been published by Gill, Marfey, and Kunz.1 (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 27-41 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Crosslinked synthetic polypeptides of poly Glu51Lys33Tyr16 (mol. wt. 31,000) and of poly Glu52Lys33Tyr15 (No. 3) (mol. wt. 52,000) containing from one to six crosslinks per molecule have been prepared by use of FFDNB, WRK and ICD reagents.The monomeric fractions of these derivatives were isolated by Sephadex G-100 chromatography. The number of crosslinks per molecule of DNPene derivatives was determined by total hydrolysis of the derivatives, isolation of O, N∊-DNPene-Tyr-Lys bridges by paper chromatography and then spectrophotometric quantitation. The number of the amide-type crosslinks in Am derivatives was established by their deamination followed by total hydrolysis and quantitation of the remaining lysine residues. Crosslinked derivatives appear to have a more compact structure, as judged by their behavior on the Sephadex columns and by their intrinsic viscosities. They were further characterized in regard to their amino acid composition, average number of the crosslinks per molecule, nitrogen content, solubility, root-mean-square end-to-end distance, and their spectral properties. Their properties recommend them as useful models for the study of the tertiary structure of proteins in solution.
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    Crosslinked synthetic polypeptides. II. Evaluation of the internal structure of intramolecularly crosslinked polymers by polarization of fluorescence measurements (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 43-55 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The introduction of intramolecular amide bonds into synthetic polypeptides produces molecules with organized spatial structure which are good models for the tertiary structure of proteins. Polarization of fluorescence measurements were used to study the internal structure and the overall rigidity of the intramolecularly crosslinked polypeptides. The graph of [(1/p) + (1/3)] against T/η changes from a straight line to a continuous curve: the temperature at which this change occurs and the slope of the straight line segment measure the stability of the internal structure of the molecule. The introduction of one to six crosslinks produces an organized internal structure that becomes more stable as the number of crosslinks increases. In contrast to the fluorescence measurements, the intrinsic viscosities, reflecting the overall hydrodynamic domain of the molecules, change (decrease) to the same extent whether one, four, or six intramolecular crosslinks are present. The overall rigidity of the polymers can be assessed by the rotational relaxation time ρh and the polarization at 10°C. p10. Both of these criteria show that the presence of six crosslinks significantly increases the rigidity, but one or four does not. The various hydrodynamic measurements may be fitted into a hierarchy of discrimination: intrinsic viscosity, sedimentation, and diffusion for size and shape; rotational relaxation time and polarization of fluorescence at a given temperature for overall molecular rigidity; and transition temperature and rate at which it is attained for internal molecular detail.
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    Determination of the dominant factors which influence the net hydration of native sodium deoxyribonucleate (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 57-68 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theory for the dependence of the net thermodynamic solvation of a macroion in an electrolyte solution is presented. The solvation in moles salt/mole macroion is shown to approach - |Zp|/v in the limit of infinite dilution of salt and macroion. The solvation in moles water/mole macroion is shown to approach zero at zero water activity. Isopiestic determinations of the hydration of sodium deoxyribonucleate in NaCl, Na2SO4, and NaClO4 solutions indicate that short-range interactions of the NaDNA with solvent account for more than half of the observed solvation. The net hydration appears to be predominantly influenced only by water activity.
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    Studies on amylose and its derivatives. Part VI. Estimation of cohesive energy densities of some amylose derivatives (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 69-78 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The cohesive energy densities (CED) of three amylose derivatives have been estimated from viscosity measurements in a range of solvents, by using methods proposed by Mangaraj and Bristow and Watson. The values assigned to the triacetate, (2.5) nitrate, and tricarbanilate are 92 ± 2, 90 ± 2, and 87 ± 2 cal./cc., respectively. The CED of unsubstituted amylose has been measured and found to be 154 ± 4 cal./cc. The results are discussed in relation to solvent power, structure, and possible correlation with the internal pressure of the polymer.
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    Ultraviolet light-induced change in collagen macromolecules (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 115-119 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Viscosity measurements and calculated rotary diffusion constants show that collagen undergoes photopolymerization when irradiated with ultraviolet light of 2537 A. Fibril formation at the same time is inhibited. The results are correlated with the aromatic amino acid content of the dangling peptides protruding from the rigid portion of the macromolecule.
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    Statistical mechanics of noncovalent bonds in polyamino acids. VII. Fluorescence as an indication of conformationThis work was supported by a research grant (AI-01473) from the National Institute of Allergy and Infectious Diseases of the National Institutes of Health, U.S. Public Health Service, and by a research grant (GB-2238) from the National Science Foundation. (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 369-377 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: It is shown how the technique of fluorescence may be used to assess conclusions about conformation which are based on a statistical mechanical treatment of simple protein models. Specifically, the state of bonding and distance between two chromophores in a molecule depend on the overall conformation, which can be computed for model systems. On the assumption that the intensity and polarization of fluorescence are affected by exciton transfer between the chromophores, it is possible to compute the effect of conformation on fluorescence. It is demonstrated that the conformational changes computed in the preceding paper will give rise to marked changes in the intensity and polarization of fluorescence.
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    Interaction between proteins and salt solutions. I. Thermodynamic parameters of dilution for gelatin and collagen (1965)
    New York : Wiley-Blackwell
    Biopolymers 3 (1965), S. 421-437 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intrinsic viscosity-temperature studies for isoelectric gelatin in KCl and KSCN aqueous solutions and equilibrium degree of swelling, ν-1, measurements for amorphous crosslinked rat tail tendons in the same solutions were carried out. On increasing salt concentration Cs, both [η] and ν-1 increase, go through a maximum, and then decrease at high Cs, KCl being more effective than KSCN in bringing about this decrease. The trend observed is similar to the variation of solubility of polypeptides and soluble proteins with Cs. By regarding a water-salt solution of a given Cs as a single diluent interacting with the protein modified by solvation and binding of ions, usual polymer solution theories were applied to the experimental results. Thus, quantities related to the entropy and enthalpy components of the excess chemical potential of the diluents were obtained. The data indicate that the initial increase of [η] and ν-1 with Cs results from the balance of an enthalpy component which, on increasing Cs, becomes less favorable to dilution and an entropy component which, conversely, becomes more favorable. The subsequent decrease of [η] and ν-1 with Cs is due to the prevailing of the enthalpy component. The maximum is reached at higher Cs for KSCN than for KCl, primarily because of the large increase in the entropy component operated by the former salt. The increase of the entropy parameter with Cs is associated to a breaking down of the coordinated water structure and to an alteration of the conformation of the macro molecules due to ion-dipole interaction and to ion absorption. The decrease in exothermicity of dilution with Cs indicates a reduced thermodynamic affinity of the diluent toward the polymer which probably results from alteration of the nature of both polymer and diluent.
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    Solution properties of synthetic polypeptides. II. Sedimentation and viscosity of poly-γ-benzyl-L-glutamate in dimethylformamide (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 781-791 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Nine samples of poly-γ-benzyl-L-glutamate (PBLG), ranging in M̄w from 19,000 to 410,000, were examined viscomctrically and by ultracentrifugation with dimethylforma-mide (DMF) at 25°C. as helicogenic solvent. The data for [η] and s0 (limiting sedimentation coefficient) as functions of M̄w were fitted well by the theories for a rigid prolate ellipsoid of revolution whose major axis increases linearly with M̄w, but whose minor axis is independent of M̄w. This implies that the overall shape of the PBLG molecule in DMF is represented by a straight cylinder whose cross section is independent of its length. The length per monomeric residue h evaluated from [η] is about 1.3 A., whereas that from s0 is about 1.6 A. No adequate explanation for this difference in h can be found at present. More serious is the fact that these hydrodynamically evaluated values of h are appreciably larger than, the value obtained from our light-scattering measurements reported previously. All these values of h from our studies are not consistent with the value characteristic of the α-helix, for which h is 1.5 A. The concentration dependence of s0 was found to agree well with the recent theoretical prediction of Peterson for cylindrical macromolecules.
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    Interaction during fibril formation of soluble collagen with cartilage proteinpolysaccharide (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 247-258 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Precipitation of soluble forms of collagen from solutions containing the soluble protein-polysaccharide (PP-L) of bovine nasal cartilage, followed by centrifugation at 100,000 g, resulted in the formation of coherent elastic pellets whose wet weights increased with the concentration of PP-L in the initial solution. Dry weights and uronic acid contents of these pellets showed that the amount of water held in the wet pellet was nearly constant for any one kind and concentration of collagen, and ranged from 20 to 100 mg./mg. PP-L in the pellet. Soluble collagens from four different sources and PP-L from three kinds of cartilage showed similar effects. Precipitation of soluble collagen in the presence of hyaluronate or dextran yielded pellets of much smaller size than those formed in the presence of PP-L. The presence of chondroitin sulfate had only a slight effect on wet pellet weights. Wet weights of pellets formed in the presence of PP-L decreased with increasing ionic strength. A model involving entanglement between insoluble collagen fibrils and the relatively stiff chondroitin sulfate chains of branched PP-L seems qualitatively capable of accounting for these results.
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    Conformational aspects of polypeptides. XVIII. Conformational studies of oligopeptides derived from L-alanineFor previous papers in this series see Goodman and Langsam. (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 305-319 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformations of oligopeptides derived from L-alanine and co-oligomers of L-alanine with γ-methyl-L-glutamate were studied in several solvents via optical rotation and far-ultraviolet spectroscopy. Calculated values for optical rotation based on model compounds were compared with experimental values for the oligomers. In trifluoroacetic and dichloroacetic acids, the oligomers and co-oligomers exhibit rotations in close agreement with predicted values based on model compounds. Thus, in these solvents only nonhelical conformations exist. In trifluoroethanol, the experimental points of molar rotation for the pentamer and larger oligomers no longer follow the predicted values. In addition, the benzyloxycarbonyl and acetyl cononamers show b0 values of about -150, which demonstrates the presence of stable helical forms for these peptides. We also examined the molar extinction coefficients of oligopeptides in the 190 mμ region and determined the values for nonhelical peptide groups. The molar extinction coefficients per amide bond for the benzyloxycarbonyl and acetyl cononamers show extensive hypo-chromism, once again indicating the presence of stable helices for these compounds in trifluoroethanol.
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    On some electrochemical aspects of actomyosin formation (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1046-1050 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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    Band centrifugation of macromolecules in self-generating density gradients. II. Sedimentation and diffusion of macromolecules in bands (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1055-1055 
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    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Effects of pressure on the helix-coil transitions of the poly A-poly U system (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1081-1090 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Studies were made of the influence of hydrostatic pressure on the helix-coil transitions of poly (A + U) and poly (A + 2U). The results were analyzed by a thermodynamic treatment which emphasized the cooperative aspect of the transitions. The helix-to-coil volume changes were found to be small and negative indicating pressure stabilization of the coil form. The significance of the results with respect to other denaturation measurements was discussed.
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    Extrinsic cotton effects of aminoacridines bound to DNA (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1091-1104 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The optical rotatory dispersion curves of the proflavine cation were measured in the spectral range 400-500 mμ. No optical activity was observed for the free cation but a large positive Cotton effect appeared in the presence of DNA. The effect of ionic strength, denaturation of the DNA, and the DNA/proflavine ratio were studied. The dependence of the magnitude of the Cotton effect on the DNA/proflavine ratio suggests that a nearest-neighbor interaction between bound proflavine molecules is necessary for optical activity. A simple statistical treatment was made which indicated that only a small number of proflavine molecules are required in close proximity for optical activity to occur. Denaturation of the DNA did not destroy the optical activity, which shows that long runs of DNA double helix are not necessary for optical activity of the ligand molecules. The optical rotatory dispersion curves of acridine orange which was bound to DNA were also measured. Two Cotton effects of opposite sense could be distinguished, the relative magnitudes of which depended on the DNA/acridine orange ratio and the state of denaturation of the DNA. The apparent differences from the proflavine-DNA system can to a large extent be explained in terms of the tendency of acridine orange to form aggregates.
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    A proposal of standard conventions and nomenclature for the description of polypeptide conformations (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1149-1150 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    URL: http://dx.doi.org/10.1002/bip.1966.360041010
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    Optical rotatory dispersion of E. coli ribosomes and their constituents (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 1-4 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Investigations have been made on the optical rotatory dispersion properties of E. coli ribosomes and their constituent RNA and proteins. The results indicate that (1) no conformational changes are involved in the formation of a 70S particle from the 50S and 308 subunits, (2) the E. coli ribosomal proteins are similar to most globular proteins with little α-helix content, and (3) the conformation of RNA and proteins inside the ribosome is very similar to that in the free state.
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    Molecular configuration of amylose and its complexes in aqueous solutions. Part II. Relation between the DP of helical segments of the amylose-iodine complex and the equilibrium concentration of free iodine (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 5-16 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The iodine which is added to an aqueous amylose solution is bound only partly by the amylose while forming the blue complex and partly remains free. The equilibrium normality of the free and the bound iodine at half-saturation of amylose by iodine is designated as [If]v and [Ib]w, respectively. The stability of the poly iodine chain formed within the axis of amylose helices depends on its length, i.e., indirectly on the DP of the amylose helices: the greater this stability, the lower the [If]v value. The amylose molecule consists of helical segments. Such a molecule may behave as a random coil. The average length of the helical segments in freshly prepared amylose-iodine complexes depends on temperature, pH, iodide concentration, the presence of other complex-forming agents, and the DP of the amylose. This latter factor is investigated in the present paper. By the aid of an automatically recording photometrictitrating device the coherent values of [Ib] and [If] were determined. Plotting these values against DPn for mechanochemically degraded as well as for periodateo-xidized amyloses resulted in curves consisting of two linear sections. The break of the curves occurred between DPn 110 and 130. It was concluded that below DPn = 100 the DP of helical segments (= sDPn) is identical to the DPn of the total molecule, i.e., the molecule consists of only a single, relatively stiff helix. Above this limit the molecule contains several helical segments. The DP of these helical segments can be calculated as follows: sDPn = 141.1 - 10.2 × 105[If]v. This equation is considered to be valid for 0.5-0.6 mg. amylose in 100 ml. 0.1N HCl at 20°C., λ = 650 mμ, euuvet diameter 3.4 cm., the feed rate of the iodate-iodide titrating solution (in acid medium resulting in a 5 × 10-3N I2 solution with a molar iodide to iodine ratio of 1.5) is 0.4ml./min. Amylose molecules of, e.g., DPn = 1380 consist of an average of 11.4 segments having a DP of about 120 and consisting of an average of 15-18 helical turns.
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    Wechselstrompolarographische kriterien der nucleinsäuredenaturierung (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 61-68 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The electrochemical possibilities for investigation of nucleic acids with high molecular weight are restricted to the determination of the adsorption behavior. According to our experience the alternating current polarography (Breyer-polarography) is mainly appropriate for the characterization of changes in the secondary structure of DNA. The Breyer-polarogram shows the alternating current of the dropping electrode in dependence on their potential which varied from 0-2 v. negative against the normal calomel electrode (NCE). By addition of native DNA to the supporting electrolyte (buffer solution) the current drops down in the range of adsorption between 0 and 1 v. At 1.16 v. against NCE the desorption takes place together with the formation of a rounded desorption peak. The investigation was carried out in phosphate buffer solution 0.1m with 0.075m NaCl or in a phosphate buffer 0.18m with 0.03m NaCl. In the pH range above pH 8 NaOH was added to realize the higher pH values. A calf thymus DNA sample having a mean molecular weight of about 18 million was used. The concentration of DNA was 5 × 10-3-1 × 10-1 wt.-%. The polarographic measurements were performed with an a.c./d.c.-polarograph “GWP 564” from Akademiewerkstätten für Forschungsbedarf der Deutschen Akademie der Wissenschaften zu Berlin (DAW). The denaturation of the double helix causes a sharp desorption peak at negative potentials of the alternating current polarogram. This new criterion for the helix-coil transition is due to formation of unpaired bases. These nearly free bases undergo a specific adsorption and the desorption takes place within a narrow potential range. Nevertheless, at present time an electron transfer to particular bases cannot be excluded at special conditions. The increase of the sharp peak permits to estimate: (a) the melting curve of the double helix in agreement with spectroscopic measurements; (b) the photolysis of the double helix; (c) the strand separation in acid and alkaline solution. In the alkaline range the sharp peak increases and reaches its maximum at pH 〉 12. In the acid range, however, no sharp peak is observed and the rounded desorption peak decreases. Therefore, the best way of following the conformation changes is to measure the current difference between the curves of the solutions with and without DNA at electrocapillary-zero-potential. On the classical d.c.-polarogram one can measure small current steps only, which may be caused mainly by capacity changes. Moreover, the scission of the molecule by ultrasonic action can be followed. In this case the rounded peak of DNA increases but the sharp peak does not appear. Similar alternating current polarograms are obtained with poly-A in the native state, because helical and unordered regions coexist in the same molecule. The very rapid indication of these structure changes allows one to carry out kinetic measurements at a fixed potential with this method.
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    Frictional coefficients of multisubunit structures. I. Theory (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 135-148 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The theory of Kirkwood for the translational frictional coefficients of structures composed of subunits has been generalized in two ways in order to consider aggregates of nonidentical subunits. One of these generalizations fails when the sizes of subunits are too disparate; the other, derived from a surface shell distribution of frictional elements, is effective over the whole range of relative sizes. It is shown that, in the limit of a continuous surface distribution, a shell model reproduces Stoke's law for a sphere. Comparison is made between the frictional coefficients of spheres, ellipsoids, and rods modeled by finite numbers of subunits and by continuous shells of frictional elements, and those calculated from other theories. Agreement is generally good, though the shell model for prolate ellipsoids of revolution deviates by a few per cent from the Perrin value.
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    The V amylose-water system: Enthalpy of hydration on the helix exterior (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 677-682 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction, V amylose hydrate ⇄ H2O + V amylose dehydrate, where the amylose hydrate and dehydrate are pseudohexagonal, helical species with packing diameters of 13.7 and 13.0 A., respectively, has been studied. The V amyloses were exposed to water vapor pressures at various temperatures, with phase determination obtained by identifying solid reactant and product from their x-ray patterns. Reversibility of reaction was found to occur over a 50-96°C. range. A Clausius-Clapeyron plot yields a ΔH of reaction of 10.4 kcal./mole of water released, which value is close to analogous heats of reaction of many common hydrate systems.
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    Study of helix-coil transition of DNA by dielectric constant measurement (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 663-676 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The thermal helix-coil transition of DNA was studied by means of dielectric constant measurements. The dielectric dispersion of native helical DNA is characterized by a large dielectric increment and a large relaxation time, whereas that of denatured coil DNA is characterized by a small dielectric increment and a small relaxation time. The dielectric dispersion of partially denatured DNA is of particular interest. At the intermediate stage of the helix-coil transition, dispersion curves which are different from either that of helix DNA or that of coil DNA appear. This is particularly pronounced for large DNA. This indicates the presence of an intermediate form of DNA. Flow birefringence measurements were carried out simultaneously. The negative birefringence of helical DNA diminishes as the helix-coil transition proceeds. However, the extinction angle remains constant, as long as it can be measured. These results indicate the absence of intermediate forms during the helix-coil transition. The discrepancy between dielectric and birefringence measurements can be resolved by assuming that the intermediate forms are not birefringent. The size distribution of native DNA and of the indicated intermediate form of DNA was studied. It is found that a logarithmic normal distribution function explains the distribution of size of DNA reasonably well.
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    Polymerization of γ-benzyl-L-glutamate N-carboxy- anhydride: Effects of conditions of polymer precipitation on the molecular weight distribution (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 695-704 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Chemistry and Pharmacology
    Notes: Poly-γ-berizyl-L-glutamate prepared by polymerization of γ-benzyl-L-glutamate NCA in dimethylformamide (DMF) with the use of diisopropylamine as the initiator was precipitated from the polymerization mixture under different conditions. A portion of the almost completely polymerized solution was treated with an excess of isopropylamine and then precipitated into diethyl ether (sample A). The remaining portion of the polymerization mixture was concentrated in a rotating evaporator, stored at room temperature for a few days, and then diluted with DMF and precipitated into diethyl ether (sample B). The molecular weight distributions of the two polymer samples were determined by the chromatographic procedure of Baker and Williams. The molecular weight of sample B is roughly three times that of sample A. However both samples have the “most probable” distribution of molecular weight. The results are interpreted according to Bamford's polymerization mechanism.
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    Masthead (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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    Sedimentation coefficient of T-even bacteriophage DNA (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 747-757 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The sedimentation coefficient of T2 phage DNA has been studied by zone centrifugation in sector-shaped preparative centrifuge tubes over a concentration range of 0.02-2.0 μg./ml. DNA. These results have been compared to a similar study in the analytical centrifuge of T4 DNA over the range of 0.50-5.75 μg./ml. DNA. A value for the sedimentation coefficient of 60.7 ± 1.8 S. was obtained by the first method and a value of 61.3 ± 1.5 S. by the second.
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    Transport, of an anionic depolarizer (CuEDTA) through DNA adsorbed on a polarized mercury surface (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 705-708 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 3 Ill.
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    Application of matrix rank analysis to the optical rotatory dispersion of TMV RNA (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 589-613 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The method of matrix rank analysis has been applied to a large body of experimental data to determine and identify the minimum number of independent spectral components that, were contained within it. The optical rotatory dispersion of TMV RNA was measured in the wavelength region 230-350 mμ, for a wide range of temperatures and ionic strengths. Over the whole range of conditions considered, the observed optical rotatory dispersion spectra were found to be a superposition of two basic spectra only. Evidence is put forward relating these spectra to the single-strand and double-strand helical forms of the molecule. A model is proposed to explain the observed spectral changes in terms of an equilibrium between these two conformations, which leads to a direct calculation of the percentage composition of the double strand at any of the conditions considered. This equilibrium, while simple in general description, appears multi-state and complex in detail. This method of analysis is both powerful and of wide applicability, since it is independent of the source of the data.
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    Transient distributions arising from initially sharp boundaries in the ultracentrifugePresented at a meeting of the Physical Biochemistry Group, British Biophysical Society, King's College, London, Jan. 4, 1967. (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 663-672 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: An infinite series solution to the Mason-Weaver equation is presented for the case in which a synthetic boundary is formed originally between solution and solvent. Digital computations based on this series, and confirmed independently, have been made for a range of parameters. For given conditions, the maximum rate of change of concentration at the meniscus and the time at which it occurs can be easily estimated by means of the curves presented. In equilibrium experiments which commence with formation of a sharp boundary, this enables the fringes to be identified with certainty.
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    Experimental thermodynamics of the helix-random coil transition. I. Influence of polymer concentration and solvent composition in the PBG-DCA-EDC system (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 649-662 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The course of the reversible helix formation of poly(γ-benzyl L-glutamate) (PBG) dissolved in a mixture of dichloroacetic acid (DCA) and 1,2-dichloroethane (EDC) was followed by measuring the heat capacity and the optical rotation of the system through the transition region. The results of these measurements indicate that the transition enthalpy ΔH the transition temperature Tc, and the Zimm-Bragg parameter σ depend considerably on the PBG concentration as well as on the composition of the solvent. For the standard state of infinite dilution, however, a linear extrapolation of the measured ΔH if values results in a standard value ΔH° = 950 cal./mole, independent of the solvent composition. The results of the calorimetric measurements are discussed in relationship to changes in optical rotation. Some peculiarities in the measured thermodynamic and optical properties in solutions with relatively high content of dichloroacetic acid are reported.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050706
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  • 192
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    General method for calculating helical parameters of polymer chains from bond lengths, bond angles, and internal-rotation angles (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 673-679 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Helical conformations of infinite polymer chains may be described by the helical parameters, d and θ (the translation along the helix axis and the angle of rotation about the axis per repeat unit), pi (the distance of the ith atom from the axis), dij, and dij (the translation along the axis and the angle of rotation, respectively, on passing from the ith atom to the jth). A general method has been worked out for calculating all those helical parameters from the bond lengths, bond angles, and internal-rotation angles. The positions of the main chain and side chain atoms with respect to the axis may also be calculated. All the equations are applicable to any helical polymer chain and are readily programmed for electronic computers. A method is also presented for calculating the partial derivatives of helical parameters with respect to molecular parameters.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050708
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  • 193
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    Volume changes accompanying collagen denaturation (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 685-689 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A dilatometric technique is employed to measure the volume changes occurring on denaturation of collagen solutions and tendons. Partial specific volumes of tropocollagen are calculated to be 0.686 ml./g. in water and 0.689 ml/g in 0.1M citrate buffer. From data on non-aqueous solutions, it is estimated that most of the volume change arises from changes in polymer configuration rather than from changes in solvation.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050802
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  • 194
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    Numerical solutions of the Lamm equation. III. Velocity centrifugation (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 697-713 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We have generated solutions to the Lamm equation to examine the effects of concentration dependence on velocity experiments. Two forms of c dependence are considered: s/s0 = 1 - kc and s/s0 = (1 + kc)-1. Features of these solutions are discussed. The magnitude of the errors resulting from the usual procedure of measuring the rate of movement of schlieren maxima or of the position at which the concentration is one half the plateau value have been examined. These errors are usually negligible after sufficient centrifugation time. The errors in using the half-plateau concentration are less than those using the movement of the peak. We have also examined a technique due to Fujita for determining D from boundary spreading when s/s0 = (1+kc)-1. This method is satisfactory when s/s0 is actually of this form, or under certain limitations when s/s0 = (1 + kc)-1. Creeth has shown that under certain conditions the concentration gradient, curve remains virtually unchanged in shape after separating from the meniscus. When this occurs it is possible to estimate s/D from the data. The condition for such a steady state is that kc0 be sufficiently large. Numerical confirmation of this method is presented in the final section.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050804
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  • 195
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    Variation in the intensity of scattered light by solutions of DNA subjected to an electric field (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 723-726 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Preliminary experiments have been carried out which measure the variation in the intensity of the light scattered by DNA solutions under the influence of an electric field. Data have been collected on the length of DNA molecules, their electric polarizability, and their dispersion behavior.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050806
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  • 196
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    Topography of nucleic acid helices in solutions. II. Structure of the double-stranded rA-rU, rI-rC, acid rA, and the triple-stranded rA-rU2 and rA-rI2 helices (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 727-747 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Information concerning the structures of rA-rU, rA-rU2 rI-rC, rA-rI2, and acid rA helices in solutions is reported. Through the use of diquaternary ammonium salts of the general structure, \documentclass{article}\pagestyle{empty}\begin{document}$ {\rm R}_1 {\rm R}_2 {\rm R}_3 \mathop {\rm N}\limits^ + ({\rm CH}_2 )n\mathop {\rm N}\limits^ + {\rm R}_1 {\rm R}_2 {\rm R}_3 \cdot 2{\rm Br}^ - $\end{document} (I), it is shown that (1) the distances between adjacent negatively charged oxygen atoms on the helix increases in the following order rA-rI2 〈 rI-rC 〈 rA-rU ≤ rA-rU2; (2) the density of the helices increases in the order. rA-rI2 〈 rA-rU 〈 rA-rU2 〈 rI-rC; (3) there is a large hydrophobia site in rA-rI2 and possibly also in rA-rU, rA-rU2, and rI-rC helices; (4) the results of the interactions between the salts of type I and the helices may be formulated in semi-quantitative terms by the use of two parameters, α, and β which are shown to be related to the charge separation and the density of the helices, respectively; (5) the studies in solutions compare favorably with the x-ray studies on the fibers; and (6) the acid rA helix differs significantly from the other helices by the fact that the electrostatic interstrand interactions between the negatively charged oxygen atom of a phosphate group and the positively charged 10-amino group of adenine contribute significantly to the stabilization of the helix, and thus it is found that the presence of the salts, I, leads to a significant destabilization of the acid rA helix.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050807
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  • 197
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    Noncomplementarity in base sequences between the cohesive ends of coliphages 186 and λ and the formation of interlocked rings between the two DNA's (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 953-966 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The half molecules of 186 DNA have been isolated by the Hg(II)-Cs2SO4 density gradient centrifugal ion technique. The buoyant densities of the two halves in CsCI at 25°C. are 1.713 and 1.709 g./cm.3, corresponding to GC contents of 54% and 50%, respectively. Similarly, 5-bromouracil labeled λ DNA halves were separated. The isolation of the four DNA halves made it possible to test for homology in base sequences between the cohesive ends of λ and those of 186. There was no indication of any significant homology in base sequences between the cohesive ends of the two DNA's, as indicated by the absence of a band with intermediate buoyant density in CsCI when either half of 186 DNA was annealed with either half of 5-bromouracil labeled λ DNA and then centrifuged. The lack of cohesion between the two DNA's made it possible to demonstrate unequivocally the formation of interlocked rings (catenanes) between the two DNA's. The existence of a dimeric catenane is evidenced by the formation of a species of intermediate buoyant density when 5-bromouracil labeled λ DNA is cyclized in the presence of cyclic 186 DNA of a relatively high concentration. The molecular weight of one DNA relative to the other can be calculated from the position of the dimeric catenane in a density gradient by using the method of Baldwin. The result was in complete agreement with our previous measurements from the sedimentation coefficients and by electron microscopy. The probability of dimeric catenane formation when one DNA is cyclized in the presence of another DNA is discussed. The experimental results agree with the theoretical expectation.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360051008
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  • 198
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    Mesure de la dispersion diélectrique en très basse fréquence de solutions de DNA (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1035-1041 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Based on the four electrodes technique, an apparatus is described which measures the Very Low Frequency (VLF) conductivity of ionic solutions, all electrode effects being completely eliminated. It is thus possible to measure the conductivity frequency dependence between 0.8 and 500 cps, with a relative error of 10-4. Applying this method to DNA solutions, one always finds a conductivity dispersion in the VLF range, which disappears when the biopolymer is heat-denatured. The relaxation time is different from one solution to another, but is always greater than 10 msee. approximately, sometimes even greater than 0.1 sec., the upper limit which one can estimate with our apparatus. The different, explanations of the DNA very low frequency polarization, assuming that its relaxation is connected with the rotational diffusion of the biopolymer long axis, is discussed.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1966.360040908
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  • 199
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    A modification of space-filling atomic models allowing rapid and accurate assembly of polypeptide conformations (1966)
    New York : Wiley-Blackwell
    Biopolymers 4 (1966), S. 1051-1052 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1966.360040911
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  • 200
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    Masthead (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967) 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050901
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