Cyclopolymerization, 12. Mechanism of free‐radical cyclopolymerization of acryloyl‐ and methacryloylmethylallylamines

Abstract

AbstractCyclopolymerizability of acryloylmethylallylamine (1b) was investigated and compared with that of methacryloylmethylallylamine (1a) which is known to yield a highly cyclized polymer with a small amount of pendant methacryloyl groups. The structural study of poly(1b) revealed that residual unsaturation consists exclusively of allyl groups and the degree of cyclization is very low. ESR measurements on the 1b polymerization system yielded only the acryloyl radical as propagating radical. Thus, 1b is incorporated into the polymer mainly through its acryloyl group and the rate‐determining step in the cyclopolymerization process of 1b is intramolecular cyclization. On the other hand, the ESR spectrum of 1a consists of cyclized and uncyclized radicals. In this case intramolecular cyclization does not proceed much faster than intermolecular propagation of the cyclized radical. ESR further revealed that the polymerization of 1a first involves the allyl group and then intramolecular cyclization occurs. The difference in cyclopolymerizabilities between 1a and 1b may be interpreted on the basis of the hypothesis that the lower the polymerizabilities of the monofunctional counterparts of unconjugated dienes, the higher their cyclopolymerizabilities.