Studies of the Cyclopolymerization in the Presence of Alkylalminum Chlorides. IV. Polymerization of o-Vinylphenyl Acrylate

Abstract

In the cyclopolymerization of o-vinylphenyl acrylate (VPA) with a conventional radical initiator and with alkylaluminum chlorides, polymers containing residual acrylic and vinylic double bonds were obtained. The cyclic structure and the sequence in the polymers were investigated by IR and NMR spectra of methylated polymers, in comparison with those of random and alternating copolymers of o-methoxystyrene—methyl acrylate; the methylated polymers were derived from the diazomethane treatment after the hydrolysis of the original cyclized polymers. The IR spectra indicated that the polymerization of VPA proceeded through head-to-tail additions with the cyclic structure of a seven-membered ring. There was a distinct difference of methoxy proton resonance in the NMR spectra of the methylated polymers derived from cyclized polymers prepared with a conventional radical initiator and in the presence of alkylaluminum chlorides. The spectrum of the former corresponded with that of the random copolymer and the spectra of the latter with that of the alternating copolymers. On the basis of the NMR measurement, the sequence of addition of the acrylic and the vinylic double bonds was random for the radical cyclopolymerization, and alternating for the cyclopolymerization in the presence of alkylaluminum chlorides. The cyclopolymerization in the presence of alkylaluminum chlorides was explained by the molecular complex mechanism.