THERMALLY-INDUCED RADICAL PROMOTED CATIONIC POLYMERIZATION USING A NOVEL N-ALLYLOXYPYRIDINIUM SALT

A system consisting of a novel N-allyloxypyridinium salt and a radical initiator is highly appropriate for the thermal initiation of cationi c polymerizations. Radicals formed upon the thermolysis (at 70 degrees C) of initiators as 2,2'-azoisobutyronitrile or benzoyl peroxide add to the double bond of the pyridinium salt N-[2-(ethoxcarbonyl)allyloxy ]-alpha-picolinium hexafluoroantimonate (1). Subsequently, the pyridin ium salt is fragmented yielding pyridinium-type radical cations, speci es able to initiate cationic polymerizations. In the case of the radic al initiator phenylazotriphenylmethane (triphenylmethaneazobenzene), t he polymerization is extremely rapid, since additionally the triphenyl methyl cation formed by electron transfer initiates the polymerization . The initiation capability of the system described was demonstrated f or a number of monomers, such as cyclohexene oxide, butyl vinyl ether and the bifunctional 3,4-epoxycyclohexylmethyl 3',4'-cyclohexanecarbox ylate. With the latter, an insoluble polymer network was readily obtai ned.