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  • 1
    Electronic Resource
    Electronic Resource
    Ion complexation in nonactin, monactin, and dinactin: A Raman spectroscopic study (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 157-185 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The ability of the macrotetrolide nactins to complex selectivity with a wide variety of cations makes these ionophorous antibiotics important model systems for the study of biologic ionic transport. We report a Raman spectroscopic investigation of the Na+, K+, Rb+, Cs+, Tl+, NH4+, NH3OH+, C(NH2)3+, and Ba++ complexes of nonactin, monactin, and dinactin in 4:1 (v/v) CH3OH/CHCl3 and in the solid state. The nactins display characteristic spectral changes upon complexation, some of which are specific for a given cation. In the K+, Rb+, Cs+, NH3OH+, and C(NH2)3+ complexes, which are apparently isosteric, the ester carbonyl stretch frequency is found to be linearly proportional to the cation-carbonyl electrostatic interaction energy, as calculated from a simplified model. Deviations for the Na+, NH4+, Tl+, and Ba++ complexes are interpreted as arising from additional nonelectrostatic interactions. Additional information is obtained from other spectral regions and from measurements of depolarization ratios. Spectra of the nactin complexes differ from each other more in the solid state than in solution, reflecting the effects of crystalline contact forces.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160112
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  • 2
    Electronic Resource
    Electronic Resource
    Nematic polymers: Excluded-volume effects (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2315-2322 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: We present a theoretical model which describes a cooperative helix-coil liquid-crystal phase transition. We show that this model predicts a first-order phase transition where certain types of chainlike macromolecules in solution make a transition from a nearly coiled to a nearly rigid conformation accompanied by a simultaneous development of long-range nematic-type liquid crystalline orientational order. From this model, the phase boundaries between nematic and isotropic phases are obtained as functions of concentration of macromolecules and of other physical parameters.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180918
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  • 3
    Electronic Resource
    Electronic Resource
    Crystallization of poly(L-proline) in the course of polymerization (1979)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 180 (1979), S. 465-472 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The heterogeneous polymerization of L-proline N-carboxy anhydride was carried out in acetonitrile and benzene, using butylamine as the initiator. Polyproline I was formed in acetonitrile and polyproline II in benzene in the course of the polymerization. The conversion attained 99% and 66% after 1 week-polymerization in acetonitrile and benzene, resp. Extended chain crystals were obtained by the polymerization in acetonitrile. On the other hand, poly(L-proline) obtained by the polymerization in benzene gave aggregates into which many growing chain ends were occluded. The differences in the crystallization behaviour during the polymerization between the two different liquids may be due to the conformation of the resultant polymers. Polyproline I exhibits a cross-section per chain of 0.709 nm2, whereas polyproline II shows only one of 0,386 nm2. The wider the cross-section per chain the more the growing, active chain ends can react with the monomer, giving rise to a higher conversion. In contrast with the case of crystallization of such α-helical chains as poly(L-alanine) during polymerization, hexagonal lamellar crystals were formed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1979.021800219
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  • 4
    Electronic Resource
    Electronic Resource
    Activity of a new polyoxime-copper complex in the reversible uptake of molecular oxygen and carbon monoxide, in the polymerization of acrylonitrile, and in the addition reaction of alcohols to acrolein (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 891-903 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neuer Polyoxim-Kupferkomplex wurde aus einem Polyoxim und Kupferacetat dargestellt, und seine Eigenschaften wurden untersucht. Es wird angenommen, daß das Polyoxim hauptsächlich aus 1,2-Bis(hydroxyimino)trimethylen-Einheiten aufgebaut ist. Der Komplex ergibt ein ESR-Signal, das demjenigen eines niedermolekularen Kupfer(II)-Komplexes ähnlich ist und dessen Intensität mit der Zunahme des Kupfergehalts abnimmt. Es wurde gefunden, daß der Komplex ein wirksamer Katalysator bei der Michael-Addition von Alkoholen an Acrolein ist, wobei ausschließlich β-Alkoxypropionaldehyd entsteht, und daß er die Polymerisation von Acrylnitril unter Wasserstoffdruck (40-90 kg/cm2) auslösen kann. Nach der Behandlung mit Hydrazinhydrat in Methanol unter Stickstoff kann der Komplex mit der Zusammensetzung Cu:OX ≈ 1:4 (Cu: Zahl der Kupferatome, OX: Zahl der- Hydroxyimino-Gruppen im Komplex) reversibel etwa 3,2dm3 molekularen Sauerstoff (in Wasser) und 0,8dm3 Kohlenmonoxid (in Methanol) per Mol Kupfer aufnehmen und abgeben. Diese Aktivität wird bei einer Verminderung des Kupfergehalts des Komplexes erheblich herabgesetzt.
    Notes: A new polyoxime-copper complex was prepared from cupric acetate and a polyoxime which is considered to consist largely of 1,2-bis(hydroxyimino)trimethylene units. The properties of the complex were studied. Its ESR spectrum was found to be similar to that of the low molecular weight copper(II) complex, whose intensity decreases with increasing copper content. The complex shows a catalytic activity in the Michael type addition reaction of alcohols to acrolein, yielding exclusively β-alkoxypropionaldehyde. In addition, it initiates the polymerization of acrylonitrile under hydrogen pressure (40 to 90 kg/cm2). Furthermore, the complex with a composition ratio Cu: OX ≈ 1:4 (Cu: number of copper atoms, OX: number of hydroxyimino groups in the complex), after being treated with hydrazine hydrate in methanol under nitrogen, can reversibly take up and release ca. 3,2dm3 of molecular oxygen (in water) and 0,8dm3 of carbon monoxide (in methanol) per mole of copper. These activities decrease remarkably with decreasing copper content of the complex.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760406
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  • 5
    Electronic Resource
    Electronic Resource
    Studies on reversible uptake of carbon monoxide, catalytic hydrogenation, reactions with benzyl halides and reproducible occurrence of an ESR-signal by a new polyoxime-palladium complex (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1217-1231 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Ein neuer Polyoxim-Palladium-Komplex wurde aus Bis(benzonitril)palladiumchlorid und einem Polyoxim dargestellt, das hauptsächlich aus 1,2-Bis(hydroxyimino)trimethylen-Einheiten besteht. Seine physikalischen und chemischen Eigenschaften wurden im Vergleich zu seinen monomeren Analoga untersucht. Es wurde gezeigt, daß der Palladiumgehalt des Komplexes mit der Menge des eingesetzten Palladium-Salzes zunimmt und der Komplex bei großem Salzüberschußeine Zusammensetzung von Pd:Cl:OX=1:2:4 erreicht, (OX: Hydroxyimino-Gruppe). Der Komplex zeigte die Eigenschaft, sich unter Abspaltung von HCI in einen Komplex mit der Zusammensetzung Pd:OX = 1 : 4 reversibel umzuwandeln. Der Komplex ist fahig, Kohlenmonoxid aufzunehmen, dessen Volumen nahezu proportional dem Quadrat des Palladiumgehaltes ist. Das Verhaltnis von Palladium zu aufgenommenem CO betragt fur den Komplex mit dem groBten Palladiumgehalt etwa 2: 1. Dieser Komplex ist zur katalytischen Hydrierung befahigt. Im Fall der Hydrierung von Styrol oder Acrylsaure-methylester handelt es sich um eine Reaktion 2. Ordnung in Bezug auf die Pd-Konzentration. Die Umsetzung von Benzylchlorid mit Methanol ergibt in Gegenwart des Komplexes Benzylmethylather. Uberdies wurde gefunden, daRder Komplex reproduzierbar ein ESR-Signal ergibt, das mit der Umwandlung in Zusammenhang steht. Als Ergebnis obiger Experimente resultiert die SchluRfolgerung, daRie Eigenschaften des Komplexes Folge einer spezifischen Pd-Pd-Wechselwirkung sind.
    Notes: A new polyoxime-palladium complex was prepared from bis(benzonitrile)palladium dichloride and a polyoxime which is considered to consist largely of 1,2-bis(hydroxyimino)-trimethylene units. Its physical and chemical properties are studied in comparison with those of the corresponding monomeric analogues. The palladium content of the complex increases with increasing amount of applied palladium salt. In case of a large excess of the salt, the resulting complex has the composition Pd:Cl:OX=1:2:4 (OX being the hydroxyimino groups). The complex may interconvert to a complex with the composition Pd:OX=1:4 and vice versa, by removal and addition of hydrochloric acid. It reversibly takes up carbon monoxide the volume of which being approximately proportional to the square of the palladium content. The ratio of palladium to carbon monoxide, taken up by the complex with the maximum palladium content, is ca. 2:1. This complex shows catalytic activity in hydrogenation. In the case of the hydrogenation of styrene or methyl acrylate, the rate is of second order in palladium content. The reaction of the complex with benzyl bromide in methanol catalytically yields benzyl methyl ether. Furthermore, it exhibits reproducibly an ESR signal, the occurrence of which corresponds to an interconversion. From these results, it is concluded that the specific properties are due to some specific Pd-Pd interactions in the complex.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760503
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  • 6
    Electronic Resource
    Electronic Resource
    Growth mechanism of crystals of glycine-L-alanine copolymer in the course of polymerization (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 373-389 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die heterogene Copolymerisation der N-Carboxyanhydride (NCA) aus Glycin und L-Alanin wurde in Acetonitril durchgeführt und der Wachstumsmechanismus der sich bildenden Copolymerkristalle untersucht. In den Ansätzen mit höherem Gehalt an Glycin erfolgt das Kristallwachstum über die Bildung der „Cross-β-Struktur“ wie bereits früher für die Bildung von Poly(S-methyl-L-cystein) vorgeschlagen. Es werden Kristalle aus gefalteten Ketten und hohe Ausbeuten erhalten. Die hohen Umsätze hängen mit der Aufweitung des Querschnitts der Ketten in den Kristallkeimen mit β-Struktur zusammen, die durch den Einbau von L-Alanin-Bausteinen in die Polyglycin-Kette verursacht wird.
    Notes: In order to examine the growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N-carboxy anhydride (NCA) and L-alanine NCA has been studied in acetonitrile. In the polymerization systems with higher contents of glycine, the crystal growth occurs through formation of the cross-β type structure as proposed previously for poly(S-methyl-L-cysteine), giving rise to chain-folded crystals and rather high conversions. The high conversion is accounted for by the widening of the cross-section of the β-chains in the backbone crystal, due to the introduction of L-alanine residues into the polyglycine chain. Copolymerization at higher contents of L-alanine leads to conversions over 90% and extended chain crystals, due to the formation of α-helices on the ribbon-like crystals composed of the β-structure just as in the case of L-alanine NCA homopolymerization, indicating the occlusion of the glycine residues into the helices.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760211
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  • 7
    Electronic Resource
    Electronic Resource
    Growth mechanism of crystals of glycine/S-methyl-L-cysteine copolymer in the course of polymerization (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 2089-2095 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to examine the growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N-carboxy anhydride (2,5-dioxo-1-oxa-3-azacyclopentane) and S-methyl-L-cysteine N-carboxy anhydride (4-methylthiomethyl-2,5-dioxo-1-oxa-3-azacyclopentane) was studied in acetonitrile. In all the polymerization systems, the crystal growth occurs through formation of the cross-β-type structure. The high conversion in the glycine-rich systems is accounted for by the widening of the cross-section of the β-chain in the backbone crystal, due to the introduction of S-methyl-L-cysteine residues into the polyglycine chain. On the other hand, the narrowing of the cross-sectional area per chain in the skeleton crystals of the oligomer gave rise to the lowering of the conversion in the S-methyl-L-cysteine-rich systems. This shows the importance of the effect of the cross-sectional area of the oligomer chain (of the β structure) in the crystal formed in the begining relative to that of the growing (α-helical) chain. The glycine residue seems to be incorporated into the crystalline lattice of the S-methyl-L-cysteine and vice versa.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780723
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  • 8
    Electronic Resource
    Electronic Resource
    Crystallization of glycine/β-benzyl-L-aspartate copolymer in the course of polymerization (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 1231-1237 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: In order to examine the structure and growth mechanism of copolymer crystals formed during polymerization, the heterogeneous copolymerization of glycine N-carboxy anhydride and β-benzyl-L-aspartate N-carboxy anhydride, initiated by butylamine, was studied in acetonitrile. In all the copolymerization systems, the crystal growth took place through formation of the cross-β structure, i.e., the introduction of glycine residues into the poly(β-benzyl-L-aspartate) chain during this particular copolymerization broke the α-helix of poly(β-benzyl-L-aspartate). The growth mechanism of the copolymer crystals was compared with that for poly(β-benzyl-L-aspartate) crystals reported previously.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790511
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  • 9
    Electronic Resource
    Electronic Resource
    Crystallization of polypeptides in the course of polymerization, 7.Part 6: cf. 6. Crystallization of poly(γ-methyl-L-glutamate), poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) (1978)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 179 (1978), S. 373-385 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Heterogeneous polymerizations of γ-methyl-L-glutamate N-carboxy anhydride (NCA), γ-benzyl-L-glutmate NCA, and β-benzyl-L-aspartate NCA were carried out using butylamine as initiator in acetonitrile at 30°C. The oligomer chains formed in the beginning of the polymerization crystallized into the antiparallel β-form and thereafter the α-helical chains grew from the active sites of the β-chains. The polymerization of γ-methyl-L-gultamate NCA proceeded to 100% conversion and accordingly gave rise to high molecular weight poly(γ-methyl-L-glutamate). The polymerizations of γ-benzyl-L-glutamate NCA and β-benzyl-L-aspartate NCA stopped at 54% and 16%, resp. The levelling-off of the conversion at such low values, in spite of the α-helical chain growth, may be due to the occlusion of the active chain ends of the resultant poly(γ-benzyl-L-glutamate) and poly(β-benzyl-L-aspartate) into the crystals. It was concluded that the interlamellar crystallization was induced by the intermolecular interaction between the benzyl groups of the polymer side chains, giving rise to the occlusion of the active growing chain ends into the interstices of the crystal formed during the polymerization.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1978.021790212
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  • 10
    Electronic Resource
    Electronic Resource
    Studies on melt spinning. VI. The effect of deformation history on elongational viscosity, spinnability, and thread instability (1976)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 20 (1976), S. 1555-1571 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of deformation history on the elongational behavior and spinnability of polypropylene melt was investigated by carrying out isothermal melt-spinning experiments. For the study, spinnerettes of different die geometries were used to investigate the effect, if any, of the entrance angle, the capillary length-to-diameter (L/D) ratio, and the reservoir-to-capillary diameter (DR/D) ratio on the elongational behavior of molten threadlines. An experimental study was also carried out to investigate the phenomenon of draw resonance in the extrusion of polypropylene melts through spinnerettes of different die geometries. Draw resonance is the phenomenon which gives rise to pulsations in the threadline diameter when the stretch ratio is increased above a certain critical value. The results of our study show that the critical stretch ratio at which the onset of draw resonance starts to occur decreases as the L/D ratio is decreased, as the entrance angle is increased, as the DR/D ratio is increased, as the melt temperature is decreased, and as the shear rate in the die is increased. Of particular interest is the observation that, at 180°C, the severity of fiber nonuniformity increases as the stretch ratio is increased, whereas at 200°C and 220°C, the severity of fiber nonuniformity first increases and then decreases as the stretch ratio is increased considerably above the critical value. A rheological interpretation of the observed onset of draw resonance is presented with the aid of the independently determined rheological data.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1976.070200613
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