Thermal and living anionic polymerization of 4-vinylbenzyl piperidine

Abstract

Elevated temperatures that are often required for controlled radical polymerization processes lead to the thermal autopolymerization of 4-vinylbenzyl piperidine. In situ FTIR spectroscopy monitored 4-vinylbenzyl piperidine autopolymerization, and pseudo-first-order thermal polymerization kinetics provided observed rate constants (k_obs). Arrhenius analysis determined the thermal activation energy (E_a) for 4-vinylbenzyl piperidine, revealing an activation energy requirement 80 kJ mol⁻¹ less than styrene due to the presence of the piperidine ring. The similarities in chemical structure of styrene and 4-vinylbenzyl piperidine suggested a thermally initiated polymerization according to the Mayo mechanism; however, the piperidine substituent enabled a proposed cationic polymerization to enhance overall polymerization rates. In the absence of thermal polymerization, living anionic polymerization of 4-vinylbenzyl piperidine provided a viable strategy for achieving piperidine-containing polymers with predictable molecular weights and narrow polydispersities. This study also reports piperidine-containing polymeric precursors for subsequent alkylation to form novel piperidinium ionomers and polyelectrolytes.