2- ethyl vinyl ether cationic copolymerizations

This article reports on the synthesis of photosensitive polymers with pendant cinnamic ester moieties and suitable photosensitizer groups by cationic copolymerizations of 2-(cinnamoyloxy)ethyl vinyl ether (CEVE) (12) with other vinyl ethers containing photosensitizer groups, and by cationic polymerization of 2-chloroethyl vinyl ether (CVE) followed by substitution reactions of the resulting poly (2-chloroethyl vinyl ether) (PCVE) with salts of photosensitizer compounds and potassium cinnamate using a phase transfer catalyst in an aprotic polar solvent. The photochemical reactivity of the obtained polymers was also investigated. 

Accordingly, N-vinylcarbcizole, ethyl vinyl ether, p-methoxystyrene (pMeOSt), and a-methylstyrene (aMeSt) are 17 400, 1380, 339, and 37 times more reactive than styrene (St). Due to this very large difference in cationic reactivity, different initiating systems bring about optimum polymerization for different monomers. This also explains why cationic statistical copolymerizations are less useful than the radical counterpart. 

The cationic copolymerizations of PNVE with 50 mol% of other vinyl ethers such as (2-phenoi )ethyl vinyl ether (PEVE), 2-isobutyl vinyl ether (IBVE), and CEVE were performed in dich loromethane using 3 mol% of BF3 CXEt)2 as the catalyst at -40 °C. 

Alkyl vinyl ethers can also be copolymerized cationically with such monomers as styrene using SnCl4/AlCl3 catalyst and in ethyl chloride solution [25-27]. 

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