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  • Polymer and Materials Science  (10)
  • Chemistry  (3)
  • 1
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 112 (1968), S. 220-224 
    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: Mit Hilfe von optisch aktiven Katalysatorsystemen wie z. B. mit n-Butyllithium/l-Mentholnatrium und n-Butyllithium/d-Borneolnatrium wurden die optisch aktiven polymeren Methyl-, Äthyl-, n-Butyl- und tert-Butyl-β-vinylacrylsäureester hergestellt. Es wurde gefunden, daß die optisch aktiven Alkoxide für die asymmetrisch induzierte Polymerisation wirksamere Cokatalysatoren sind als die entsprechenden Äther.Die darestellten Polymeren wurden durch die optischen Rotaionspersionskurven und die Infrarotabsorptionsspektra charakterisiert.
    Notes: Optically active polymers of methyl, ethyl, n-butyl, and tert-butyl β-vinylacrylates were synthesized by using optically active catalyst systems such as n-BuLi/sodium l-menthoxide and n-BuLi/sodium d-bornoxide. The optically active alkoxides were found to be even more efficient cocatalysts for the asymmetric-induced polymerization than were the corresponding ethers.The polymers obtained were characterized from their optical rotatory dispersion curves and infrared absorption spectra.
    Additional Material: 3 Ill.
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  • 2
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 28 (1958), S. 450-451 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Tab.
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  • 3
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 112 (1968), S. 210-219 
    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: Methylphenylketen wurde im Temperaturbereich von -78 bis -20°C mit verschiedenen Organometallkatalysatoren und in verschiedenen Lösungsmitteln polymerisiert. Die erhaltenen Polymeren haben ausschließlich Polyesterstruktur. Es besteht demnach ein Unterschied zum Dimethylketen, bei dem frühere Ergebnisse darauf hideuten, daß je nach Katalysator und Lösungsmittel Polyester-, Polyacetal- oder auch Polyketon-Strukturen entstehen.Die Copolymerisation von Methylphenylketen mit Benzaldehyd ergibt ein 1:1-Copolymeres. Die Hydrogenolyse mit Lithiumaluminiumhydrid zeigt, daß es sich praktisch um ein rein alternierendes Copolymers vorwiegend vom Polyestertyp handelt.Sowohl das Homopolymere als auch das Copolymere des Methylphenylketens sind viel weinger kristallin als das Polymethylketen.
    Notes: Methylphenylketene was polymerized by a variety of organometallic catalyst/solvent systems at -78 to -20°C. The polymer obtained was found to be exclusively polyster, in contrast to previous results which indicated that dimethylketene gave polyester, polyester, polyacetal, and polyketone, depending on the catalyst/solvent systems used.Copolymerization of methylphenylketene with benzaldehyde led to the formation of a 1:1 copolymer. Hydrogenolysis of the copolymer showed that it was practically an alternating copolymer and that its structure was predominantly of the polyester type.Both the homopolymer and copolymer have poor crystallinity as compared with those obtained from dimethylketene.
    Additional Material: 5 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 2433-2435 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 2 Tab.
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  • 5
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Reactivities of propenyl alkyl ethers toward various cationic agents are summarized, and the effects of a β-methyl group and geometrical isomerism are discussed on the basis of the extended Hückel molecular orbital theory. The reactions considered include cationic polymerization, acid-catalyzed hydrolysis, and silver-ion complexation. The effects of a β-methyl substitution on the reactivity of vinyl ether are different depending on the type of the reactions. The substitution enhances the reactivity of vinyl ether in homogeneous polymerization, whereas it reduces the reactivity in hydrolysis. This contrasting effect of a β-methyl group was found to be compatible with the results of the theoretical calculations of the electronic energy changes accompanying the formation of the relevant transition states. A π-complex-type transition state was concluded for the cationic polymerization. Several lines of experimental evidence in support of the conclusion are presented.
    Additional Material: 1 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 1447-1454 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Phenyl vinyl ether (M1) has been copolymerized with its various ring-substituted derivatives (M2) in toluene at -78°C with stannic tetrachloride as catalyst. The substituents investigated include p-CH3O, m-CH3O, p-CH3, m-CH3, p-Cl, and m-Cl. The course of copolymerization was followed by gas chromatographic determinations of residual monomers, and the monomer reactivity ratios were evaluated by use of the integral form of the Mayo-Lewis copolymerization equation. Except for the unusual case of the m-CH3O derivative, the observed values of log (1/r1) were found to be linearly correlated with Hammett's σ constants, the reaction constant being ρ = -1.76 with the correlation coefficient r = 0.990. Comparisons of these results with the existing data for the styrene copolymerizations have enlightened the behavior of the oxygen atom in transmitting the electronic effects of ring substituents onto the reaction center.
    Additional Material: 3 Ill.
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  • 7
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: cis- and trans-Propenyl isobutyl ethers were copolymerized with each other and each with vinyl isobutyl ether separately under various conditions. In homogeneous polymerizations a cis-β-methyl substitution on vinyl isobutyl ether apparently enhanced the reactivity, whereas the trans substitution tended to reduce it slightly. In heterogeneous catalysis, on the other hand, a β-methyl group on the vinyl ether, whether cis or trans, greatly reduced the reactivity, probably because of the steric hindrance toward the adsorption of monomers on the catalyst surface. The relative reactivities of cis- and trans-propenyl isobutyl ethers ranged from 2 to 20, depending on the polymerization conditions. The polymer end formed from the cis monomer exhibited special steric effects. It was concluded that even in homogeneous media the rotation of the polymer end around the terminal carbon-carbon bond is restricted.
    Additional Material: 2 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 1001-1007 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relative cationic polymerizabilities of the geometrical isomers of various alkenyl alkyl ethers were studied both in copolymerizations with each other and in their respective copolymerizations with vinyl isobutyl ether as standard. Copolymerizations were carried out in methylene dichloride at -78°C. with boron trifluoride etherate as catalyst. The cis isomers have been found to be more reactive than the corresponding trans isomers. A primary alkyl substituent on the β-cis position of vinyl ethyl ether enhances the reactivity. Yet the steric effect is noticeable when the substituents are bulky. Compounds substituted with cis-β-isobutyl and with β-dimethyl showed little tendency to homopolymerization. It was proved that the polymer ends derived from cis and from trans monomers are respectively different in character because of the restricted rotation of the end unit around the terminal carbon-carbon bond. The alternation tendency, remarkable in the copolymerization of cis monomers with vinyl ether, was explained in terms of the cis-opening mechanism.
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  • 9
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 3045-3052 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic copolymerizations of cis- and trans-propenyl ethyl ethers (PEE) with isobutenyl ethyl ether (IBEE) were carried out in methylene chloride at -78°C with the use of boron trifluoride etherate as catalyst. Monomer reactivity ratios were r1 = 24.0 ± 2.4 and r2 = 0.02 ± 0.02 for the cis-PEE (M1)-IBEE (M2) system and r1 = 19.1 ± 1.8 and r2 = 0.04 ± 0.02 for the trans-PEE (M1)-IBEE (M2) system, indicative of the reactivity order: cis-PEE 〉 trans-PEE ≫ IBEE. In separate experiments, these β-methyl-substituted vinyl ethers were allowed to react with various acetals in the presence of boron trifluoride etherate. The relative reactivities of these ethers were generally found to decrease in the order: cis-β-monomethylvinyl 〉 vinyl 〉 trans-β-monomethylvinyl 〉 β,β-dimethylvinyl. Comparisons of these results with previously published copolymerization data have permitted the conclusion that, in both the copolymerizations and acetal additions, the single β-methyl substitution on vinyl ethers exerts little steric effect against their additions toward any alkoxycarbonium ion, whereas the β,β-dimethyl substitution results in a large adverse steric effect toward both β-monomethyl- and β,β-dimethyl-substituted alkoxycarbonium ions.
    Additional Material: 2 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 9 (1971), S. 163-174 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: cis- and trans-1-Ethoxy-1,3-butadienes were polymerized by a variety of cationic agents in various solvents at -78°C. The trans ether, which is the more stable isomer, was found to have greater polymerizability than the cis ether. The trans monomer gave polymers predominantly of the trans-1,4 type, whereas the cis monomer showed a tendency toward the formation of polymers having the microstructure of the 1,2 type. It was concluded that, in the cis ether, the carbon atom which is the most vulnerable to the attack of carbonium ions is the one at the 2-position, whereas, in the case of the trans isomer, the terminal 4-carbon is the most reactive center. The conclusion was confirmed from the results of acetal addition reaction catalyzed by boron trifluoride etherate. The marked contrast in the mode of reaction of the two isomeric ethers toward carbonium ions was interpreted in terms of the difference in the degree of bonding in the transition state.
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