Thermally induced radical promoted cationic polymerization using a novel N‐allyloxypyridinium salt

Abstract

AbstractA system consisting of a novel N‐allyloxypyridinium salt and a radical initiator is highly appropriate for the thermal initiation of cationic polymerizations. Radicals formed upon the thermolysis (at 70°C) of initiators as 2,2′‐azoisobutyronitrile or benzoyl peroxide add to the double bond of the pyridinium salt N‐[2‐(ethoxcarbonyl)allyloxy]‐α‐picolinium hexafluoroantimonate (1). Subsequently, the pyridinium salt is fragmented yielding pyridinium‐type radical cations, species able to initiate cationic polymerizations. In the case of the radical initiator phenylazotriphenylmethane (triphenylmethaneazobenzene), the polymerization is extremely rapid, since additionally the triphenylmethyl cation formed by electron transfer initiates the polymerization. The initiation capability of the system described was demonstrated for a number of monomers, such as cyclohexene oxide, butyl vinyl ether and the bifunctional 3,4‐epoxycyclohexylmethyl 3′,4′‐cyclohexanecarboxylate. With the latter, an insoluble polymer network was readily obtained.