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  • 1
    Electronic Resource
    Electronic Resource
    Phase transition in swollen gels. 6. Effect of aging on the extent of hydrolysis of aqueous polyacrylamide solutions and on the collapse of gels (1984)
    s.l. : American Chemical Society
    Macromolecules 17 (1984), S. 2868-2874 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00142a072
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  • 2
    Electronic Resource
    Electronic Resource
    Swelling and photoelastic behaviour of ionized hydrogels of poly(acrylic acid) (1996)
    Springer
    Polymer bulletin 37 (1996), S. 791-798 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary The photoelastic and swelling behaviour of poly(acrylic acid) gels swollen in 1 M NaCl aqueous solution was studied as a function of crosslinking degree (1–5 wt.% ethylene glycol dimethacrylate) and degree of ionization αg = 0 − 1. The degree of swelling passes through a minimum at αg ≐ − 0.15 regardless of the degree of crosslinking, probably due to the formation of hydrogen bonds between ionized and nonionized carboxyl groups. In the same neutralization region, the equilibrium modulus reaches a maximum; on the other hand, the modulus related to the dry state is independent of α for all crosslinker concentrations. Thus the mechanical behaviour of poly(acrylic acid) gels is in accord with the Gaussian theory and no contribution of permanent physical interactions to the modulus is observed. The optical behaviour is more complex — the sign of the stress-optical coefficient C e changes three times with increasing α due to the orientation of the side groups. The analysis of the optical data shows that the C e value is controlled by the degree of swelling and by the ionization.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295779
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  • 3
    Electronic Resource
    Electronic Resource
    Dynamic mechanical behaviour of random copolymers of a LC-methacrylate and octyl methacrylate (1997)
    Springer
    Polymer bulletin 38 (1997), S. 219-226 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract. The dynamic mechanical behaviour of random copolymers of LC monomer-1-(hexyloxycarbonyl)ethyl 4-[4-(methacryloyloxy)benzoyloxy]benzoate (HB) and octyl methacrylate (OMA) was studied in the main transition and flow regions. Even though the aliphatic end groups of the side chain of HB and OMA are roughly the same, the T g temperature of poly(HB) is ∼ 80 K higher than that of poly(OMA); this fact is due to the presence of the stiff phenyl benzoate mesogenic group in the side chain of HB. With increasing content of OMA in the copolymer the superimposed curves of the storage G′ p and loss G′′ p moduli at a constant temperature shift towards shorter frequencies. It has been shown that this shift is mainly due to an increase of the free volume in the copolymers with increasing content of OMA. While HB monomer shows liquid crystalline (LC) properties, its polymer (poly(HB)) and random copolymers with OMA show only isotropic thermal behaviour because no flexible spacer is present in the side chain of HB which would decouple the main chain and mesogenic group motions. This means that neither the homopolymer of HB, nor its copolymers with a flexible comonomer retain the LC properties of the starting LC monomer, HB.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002890050041
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  • 4
    Electronic Resource
    Electronic Resource
    The synthesis of pyridyl-substituted polyurethanes and copolyurethanes (1995)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 231 (1995), S. 171-186 
    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: Durch Polyaddition von Diphenylmethan-4,4′-diisocyanat oder Dicyclohexylmethan-4,4′-diisocyanat mit 2-Methyl-2-(4-pyridyl)propan-1,3-diol (MPyP) wurden neue reaktive Polyurethane hergestellt, deren Struktureinheiten mit Pyridinringen substituiert sind. Copolyurethane aus diesem Diol wurden in einem Ein- bzw. Zweistufenprozeß in Substanz oder in Diglyme-Lösung hergestellt, wobei als Comonomere Hexan-1,6-diol (HD), α,ω- Dihydroxypoly(oxyethylen)e mit verschiedenen Molekulargewichten (POE 400,1000 und 2000) oder α,ω-Dihydroxypoly(oxypropylen) (PPO 400) eingesetzt wurden. Die erhaltenen Pyridin-substituierten Polyurethane und Copolyurethane wurden durch 1H-NMR- und 13C-NMR-Spektroskopie und durch die Grenzviskosität [λ] charakterisiert. Die Pyridineinheiten wurden acidometrisch (HClO4) bestimmt. Die Reaktivität der OH-Gruppen in MPyP bezüglich der Isocyanat-Gruppe wurde charakterisiert, indem die Geschwindigkeitskonstante der Reaktion von MPyP mit Phenylisocyanat bestimmt wurde. Der erhaltene Wert von 2,45 · 10-3 dm3 mol-1 s-1 (25°C) liegt um eine Größenordnung höher als die Geschwindigkeits-konstante für die Addition von Hexan-1,6-diol. Diese Differenz wurde mit einem katalytischen Mechanismus bei der Addition von MPyP interpretiert.
    Notes: New reactive polyurethanes with structure units substituted with pyridine rings were prepared by the polyaddition reaction of diphenylmethane-4,4′-diisocyanate or dicyclohexylmethane-4,4′-diisocyanate with 2-methyl-2-(4-pyridyl)propane-1,3-diol (MPyP). Copolyurethanes based on this diol were synthesized by a one- or two-step procedure carried out in bulk or diglyme solution using hexane-1,6-diol (HD), α,ω-dihydroxypoly(oxyethylene)s of various molecular weights (POE 400, 1000 and 2000) or α,ω-dihydroxypoly(oxypropylene) (PPO 400) as comonomers.Pyridyl-substituted polyurethanes and copolyurethanes were characterized by their 1H and 13C NMR spectra and limiting viscosity numbers [η]. The pyridine units were determined acidimetrically (HClO4). The reactivity of the OH groups of the pyridine diol towards NCO groups was characterized by determining the rate constants of its reaction with phenyl isocyanate. The obtained value of 2.45 × 10-3 dm3 mol-1 s-1 (25°C) was by an order of magnitude greater than the rate constant for the addition of hexane-1,6-diol. This difference was interpreted in terms of a catalytic mechanism for the addition of MPyP.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1995.052310115
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  • 5
    Electronic Resource
    Electronic Resource
    The hydrogenation of HO-terminated telechelic polybutadienes in the presence of a homogeneous hydrogenation catalyst based on tris(triphenylphosphine)rhodium chloride (1989)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 165 (1989), S. 165-180 
    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 die Kinetik der Hydrierung der Mehrfachbindungen in den HO-terminierten telechelen Polybutadienen verfolgt, die durch anionische und radikalische Polymerisation hergestellt worden sind. Die Geschwindigkeit der Addition von Wasserstoff an die π-Bindungen dieser Polydiene wurde in Anwesenheit von Tris(triphenylphosphin)rhodium (I) chlorid als homogenen Hydrierungskatalysator durch die chemische Struktur der Ausgangspolybutadiene, ihre Konzentration im Lösungsmittel, den Partialdruck des Wasserstoffs, die Katalysatorkonzentration und die Temperatur bestimmt.Der Einfluß der angegebenen kinetischen Parameter auf die Geschwindigkeit der Hydrierungsreaktion kann im Sinne des Wilkinson-Reaktionsmechanismus der Hydrierung von Alkenen in Anwesenheit des Rh(I)-Komplexes interpretiert werden. Das anionische Prepolymere, das überwiegend 1,2-Struktureinheiten enthält, reagiert mit Wasserstoff zweimal schneller (k = 0.093 mol-1 dm3 s-1) als das radikalisch hergestellte Prepolymere (k = 0.045 mol-1 dm3 s-1). Bei der Hydrierung der Mehrfachbindungen kommt es oft zur partiellen Abnahme des Hydroxygruppengehalts in den modifizierten telechelen Prepolymeren; der Umfang dieser Reaktion wird durch die Reaktionsbedingungen der Hydrierungsreaktion bestimmt.
    Notes: The hydrogenation kinetics of multiple bonds in HO-terminated telechelic polybutadienes was investigated using two types of these prepolymers prepared by the anionic and radical polymerization. The rate of addition of hydrogen to the π-bonds of these polydienes in the presence of tris(triphenylphosphine) rhodium chloride as a homogeneous hydrogenation catalyst was determined by the chemical structures of the starting polydienes, their concentration in the solvent, the partial hydrogen pressure, the concentration of the catalyst, and the temperature.The effect of kinetic parameters given above on the rate of hydrogenation reaction can be interpreted in the sense of Wilkinson's reaction mechanism of the hydrogenation of alkenes in the presence of the Rh(I)-complex. Due to the predominant 1,2-structural units, the anionic prepolymer reacted twice as quickly with hydrogen (k = 0.093 mol-1 dm3 s-1) compared with the radical prepolymer (k = 0.045 mol-1 dm3 s-1). During the hydrogenation of multiple bonds there is a partial loss of hydroxy groups in modified telechelic prepolymers; the extent of this reaction depends on reaction conditions of the hydrogenation reaction.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1989.051650114
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  • 6
    Electronic Resource
    Electronic Resource
    Synthesis of 2-(2-carboxybenzoyloxy)ethyl methacrylate and its radical polymerization and copolymerization with butyl methacrylate (1992)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 201 (1992), S. 33-48 
    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 Bedingungen für die Synthese von 2-(2-Carboxybenzoyloxy)ethylmethacrylat (CEM) durch Alkoholyse von Phthalsäureanhydrid (PA) mit 2-Hydroxyethylmethacrylat (HEMA) wurden optimiert. Für die nicht katalysierte, die basen- und säurekatalysierte Reaktion von PA mit HEMA bei 50°C wurden als Geschwindigkeitskonstanten zweiter Ordnung die Werte 4,74 × 10-6, 14,5 × 10-5 bzw. 5,4 × 10-5 dm3 mol-1 s-1 ermittelt. Unter Säurekatalyse fand außerdem eine weitgehende Veresterung von CEM unter Bildung von Bis(2-methacryloyloxyethyl)phthalat statt. Für die Emulsionspolymerisation von CEM (Wasserlöslichkeit 13 mmol dm-3 bei 25°C) in Gegenwart von Natriumdodecylsulfat als Emulgator mit dem Initiatorsystem K2S2O8 - K2S2O5 wurde nach dem Emulsionspolymerisationsmodell von Smith-Ewart eine Wachstumsgeschwindigkeitskonstante von 610 dm3 mol-I s-l bestimmt. Die Copolymerisationsparameter und Q- und e-Werte von CEM für die radikalische Copolymerisation von CEM (M1) mit Butylmethacrylat (M2) betragen r2 = 0,85, r2 = 0,75, Q = 0,82 und e = 0,4.
    Notes: Conditions of the synthesis of 2-(2-carboxybenzoyloxy)ethyl methacrylate (CEM) by the alcoholysis of phthalic anhydride (PA) with 2-hydroxyethyl methacrylate (HEMA) were optimized. For the uncatalyzed, base-catalyzed and acid-catalyzed reaction of PA with HEMA at 50°C the respective second-order rate constants were 4.7 × 10-6, 14.5 × 10-5 and 5.4 × 10-5 dm3 mol-1 s-1. Also, a consecutive esterification of CEM with formation of bis(2-methacroyloxyethyl)phthalate took place under conditions of the acid catalyzed reaction. The emulsion polymerization of CEM (solubility in water 13 mmol dm-3 at 25°C) was carried out in the presence of sodium dodecyl sulfate as the emulsifier and of the redox initiation system based on K2S2O8-K2S2O5. Using the Smith-Ewart model of emulsion polymerization, the growth rate constant of CEM, kp = 610 dm3 mol-1 s-1 at 25°C was determined. The monomer reactivity ratios and Q and e values determined for the radical copolymerization of CEM (M1) with butyl methacrylate (M2) were r1 = 0.85, r2 = 0.75, Q = 0.82, and e = 0.4.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1992.052010104
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  • 7
    Electronic Resource
    Electronic Resource
    Über die durch Rh(I)-Komplexe katalysierten chemischen Umwandlungen des 2-Chlor-1.3-butadiens (1972)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 156 (1972), S. 225-241 
    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: An investigation has been made of the transformations of chloroprene into cyclic dimers and polychloroprene in the presence of variously 1.3-substituted 1.3-propanedione chelates of bis-ethylene rhodium(I).No 1.6-dichloro-1.5-cyclooctadiene could be detected in the reaction products. The rate of formation of 1-chloro-4-(α-chlorovinyl)-cyclohexene in the presence of the Rh(I) complexes was higher by 1/4 only than in pure chloroprene and did not depend upon the character of the 1.3-substituents in 1.3-propanedione. The time increments in the concentration of 1.2-dichloro-1.2-divinylcyclobutane (D4) and of polychloroprene correlated with HAMMETT'S σI constants of the 1.3-substituents in the chelate ring of 1.3-propanedione. The order of polymerization with respect to the concentration of the Rh(I) complex was 0.42; the order of dimerization of chloroprene into D4 was -0.43. The catalytic effect of the Rh-complex upon the polymerization of chloroprene was increased by addition of dry HCl to the mixture. The polymerization was faster with the (CH3COCHCOCH3)Rh(benzoquinone) complex than with the (CH3COCHCOCH3)Rh(C2H4)2 complex. The τ values of the NMR spectrum of the polymer corresponded to the spectrum of trans-1.4-polychloroprene.Respecting the kinetic data and the reaction products the mechanism of rhodiumcatalyzed transformations of chloroprene is discussed.
    Notes: Die Umwandlungen des Chloroprens in cyclische Dimere und in Polychloropren durch verschiedene 1.3-substituierte 1.3-Propandionchelate des Bis-äthylen-rhodium(I) wurden studiert.In den Reaktionsprodukten wurde kein 1.6-Dichlor-1.5-cyclooctadien festgestellt. Die Bildungsgeschwindigkeit von I-Chlor-4-(α-chlorvinyl)-cyclohexen war in Anwesenheit von Rh(I)-Komplexen nur um 1/4 höher als in reinem Chloropren und hing nicht vom Charakter der 1.3-Substituenten im 1.3-Propandion ab. Die zeitliche Zunahme der Konzentration des 1.2-Dichlor-1.2-divinyl-cyclobutans (D4) und des Polychloroprens korrelierte mit den HAMMETTschen σI-Konstanten der 1.3-Substituenten im Chelatring des 1.3-Propandions. Die Reaktionsordnung der Polymerisation in bezug auf die Konzentration des Rh(I)-Komplexes entsprach 0,42 und die der D4-Dimerisation dem Wert -0,43. Der katalytische Einfluß des Rh-Komplexes auf die Polymerisation des Chloroprens nahm bei Anwesenheit von trockenem Chlorwasserstoff zu. Mit dem Komplex (CH3COCHCOCH3)Rh(Benzochinon) war die Polymerisation schneller als mit dem Komplex (CH3COCHCOCH3)Rh(C2H4)2. Die τ-Werte im NMR-Spektrum des Polymeren entsprachen denen des trans-1.4-Polychloroprens.Auf Grund der kinetischen Daten und der Produkte wird der Reaktionsmechanismus diskutiert.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1972.021560117
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  • 8
    Electronic Resource
    Electronic Resource
    Über die homopolymerisation des N-(pentachlorphenyl)maleinimids und des N-(2,4,6-tribromphenyl)maleinimids (1977)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 178 (1977), S. 55-68 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: New monomers with a high content of halogens, N-(pentachlorophenyl) maleimide (1) and N-(2,4,6-tribromophenyl) maleimide (2) were prepared. The products of their radical polymerization consist of oligomers. Of these, products with the degree of oligomerization, n, ranging from 1-4 and from 1 to 3 were separated on a gel chromatograph for 1 and 2, respectively. Their structures were determined from the mass spectra. The elution volumes Vn of the individual oligomers were found to be a linear function of log Mn. The radical polymerization mechanism of 1 and 2 is discussed on the basis of the character of oligomers.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1977.021780107
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of dilution during network formation on the sol fraction and elasticity of polyurethane networksDedicated to Prof. H.-J. Cantow for his contribution to polymer science on the occasion of his 65th birthday (1989)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 190 (1989), S. 883-891 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The effect of dilution at network formation (polymer volume fraction v(0) = 1 - 0,4) on the fraction and equilibrium photoelastic behaviour of polyurethane networks was investigated. The networks were prepared from poly(oxypropylene)triol and 4,4′-methylenedi(phenyl isocyanate) with various mole ratios of reactive groups 1 ≤ rH = [OH]/[NCO] ≤ 1,5. From a comparison between the experiments and the theory of branching processes we find that: (a) with both increasing ratio rH and increasing dilution the fraction of bonds lost in elastically inactive cycles increases from 0,02 to 0,06; (b) the experimental reduced equilibrium moduli Gr of the predominant majority of samples are higher than those theoretically predicted by the Flory junction-fluctuation theory for the front factor A = 1. Also the decrease of Gr with dilution (expressed as volume fraction of diluent during network formation v(0)) is very steep, thus supporting the contribution of permanent interchain constraints to the overall Gr value.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1989.021900421
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  • 10
    Electronic Resource
    Electronic Resource
    Über den einfluß der 2-arylimino-3-penten-4-olatobis(äthylen)-rhodium(I)-chelate auf die polymerisation und dimerisation des 2-chlor-1,3-butadiens (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 1679-1688 
    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: The effect of 2-arylimino-3-pentene-4-olatobis(ethylene)rhodium(I)-chelates (1a-f) on the dimerization and polymerization of 2-chloro-1,3-butadiene (chloroprene) was investigated. 1,6-dichloro-1,5-cyclooctadiene could not be detected in the reaction products and the polymerization of chloroprene started without any induction period. The time increments in the concentration of 1,2-dichloro-1,2-divinylcyclobutane (D4) and of polychloroprene correlate with Hammett's σ-constants of the p-substituents in the phenyl group of the chelates. The orders of polymerization and dimerization with respect to the concentration of Rh(I) chelate were 0,5 and -0,4. On the basis of the data obtained, the mechanism of the catalyzed dimerization and polymerization of chloroprene is discussed.
    Notes: Der Einfluß der 2-Arylimino-3-penten-4-olatobis(äthylen)rhodium(I)-Chelate (1a-f) auf die Dimerisation und Polymerisation des 2-Chlor-1,3-butadiens wurde untersucht. In den Reaktionsprodukten konnte kein 1,6-Dichlor-1,5-cyclooctadien gefunden werden, und die Polymerisation des Monomeren verlief ohne Induktionsperiode. Die zeitliche Konzentrationszunahme an 1,2-Dichlor-1,2-divinylcyclobutan (D4) und die Polymerisationsgeschwindigkeit korrelieren mit den Hammetschen σ-Konstanten der p-Substituenten in der Phenylgruppe der 1-Arylimino-3-propanon-chelate des Rh(I). Die Reaktionsordnungen der Polymerisation und der Dimerisation in bezug auf die Konzentration des Rh(I)-Chelats entsprechen übereinstimmend Werten von 0,5 und -0,4. Aufgrund der kinetischen Daten wird der Mechanismus der katalysierten Dimerisation und Polymerisation des 2-Chlor-1,3-butadiens diskutiert.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760612
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