Anionic Polymerization of α-(Trifluoromethyl)Acrylate

Abstract

Methyl α-(trifluororaethyl)aerylate (MTFMA) readily undergoes anionic polymerization by initiation with organic and inorganic salts in the presence of 18-crown-6 to provide high molecular weight polymers in good yields. These weak anionic initiators are effective because of the low electron density (e=2.5) on the β-carbon of MTFMA. Amines are also effective initiators. Pyridine forms a very stable charge transfer complex with MTFMA. While wet 2,6-di-t-butylpyridine can initiate the polymerization, the hindered amine is not effective when dry, suggesting that the initiating species is a hydroxide in this case. However, dry pyridine gives rise to a vigorous polymerization with a color development, which suggests that pyridine itself is capable of initiating anionic polymerization of MTFMA. n-Butyllithium readily adds to the β-carbon of MTFMA but the adduct species further reacts with the initiator to introduce additional n-butyl group into the carbon bearing the fluorine atoms. Phenylmagnesium bromide and α -methylstyrene tetramer dianion fail to induce the anionic polymerization presumably due to the attack of the initiator onto the CF₃ group. The thermal degradation behavior of the polymers depends very much on the initiator employed, suggesting the occurrence of depolymerization from the initiator side of the chain.