LIVING CATIONIC POLYMERIZATION OF CYCLOHEXYL VINYL ETHER

The cationic polymerization of cyclohexyl vinyl ether (CHVE) initiated by alpha-halogeno ethers in the presence of a Lewis acid activator ha s been investigated first. In conditions leading to a living polymeriz ation of alkyl vinyl ethers (ethyl, isobutyl, etc.), an extremely fast polymerization, accompanied by chain transfer reactions, is observed with CHVE. In fact, we have shown that the polymerization of this mono mer may be directly initiated by the HI and HCl adducts of CHVE, in th e absence of any electrophilic activator. However, even in these condi tions, the polymerization cannot be controlled. A ''living'' polymeriz ation of CHVE was finally obtained by addition of ammonium salts (NBu4 X; X = Cl, Br, I) to the systems free of electrophilic activators. The added salts stabilize the alpha-halogeno ether chain ends and reduce the overall reactivity. Using this procedure, we have synthesized poly (CHVE)s with M(n)'sBAR ranging from 6 . 10(3) to 4 . 10(4) g . mol-1 ( in good agreement with the predicted values assuming the formation of one polymer chain per initiator molecule) and narrow molecular weight distributions (M(w)BAR/M(n)BAR < 1,2). Though most of poly(alkyl vinyl ether)s exhibit glass transition temperatures far below 0-degrees-C, the glass transition temperature of the poly(CHVE) is close to + 50-de grees-C, indicating that this monomer can be used as a precursor to ri gid poly(vinyl ether) blocks.