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  • 1
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A common-ion salt, tetra-n-butylammonium perchlorate, was found to affect the monomer reactivity ratios in the cationic copolymerization by acetyl perchlorate of styrene with p-methylstyrene and of 2-chloroethyl vinyl ether with p-methylstyrene, but not those for the copolymerization of 2-chloroethyl vinyl ether with isobutyl vinyl ether. In the copolymerization of p-methylstyrene with styrene or with 2-chloroethyl vinyl ether, the addition of the common-ion salt in a polar solvent shifted the monomer reactivity ratios to those in a less polar solvent. The molecular weight distribution analysis of the copolymer suggested that the addition of the common-ion salt depresses the dissociation of propagating species. Therefore, it was concluded that a propagating species with a different degree of dissociation shows a different relative reactivity towards two monomers. The nature of propagating species was also discussed on the basis of the common-ion effect on the monomer reactivity ratios in various solvents.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 12 (1974), S. 613-626 
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Ring-substituted phenyl propenyl ethers were found to form homopolymers without any rearrangement by metal halides. Phenyl propenyl ethers were less reactive than the corresponding phenyl vinyl ethers in cationic polymerization. In order to study the electronic effect of a substituent on the reactivity, cis-p-Cl,p-CH3, and p-CH3O-phenyl propenyl ethers were copolymerized with phenyl propenyl ether in methylene chloride at -78°C with stannic chloride-trichloroacetic acid, and their 1H- and 13C-NMR spectra were measured. The reaction constant ρ against Hammett σp was -2.1. The cis-phenyl propenyl ethers were slightly more reactive than the corresponding trans isomers. On the other hand, an o-methyl group decreased the reactivity of phenyl propenyl ether. The low reactivity of o-methyl phenyl propenyl ether was attributed to the steric hindrance between the propagating carbocation and the monomer.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To determine the effect of the dissociation of propagating species on the relative reactivity of monomers, 2-chloroethyl vinyl ether was copolymerized with p-methoxystyrene or with p-methylstyrene by using iodine in various solvents at 0°C. A common-ion salt (tetra-n-butylammonium iodide or tetra-n-butylammonium triiodide) was added to these copolymerization systems in a polar solvent to depress the dissociation of the propagating species. The addition of a common-ion salt increased the vinyl ether content in the copolymer. The more the dissociation of propagating species was depressed, the more the vinyl ether content in the copolymer increased. This effect of common-ion salt was in agreement with that of decreasing solvent polarity which yielded vinyl ether-rich copolymer as well. Therefore, the change of the monomer reactivity ratio by the solvent polarity, which used to be explained in terms of a selective solvation, must be reconsidered from the viewpoint of varying degrees of the dissociation of propagating species.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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