A degradable copolymer of 2-methylene-1,3-dioxepane and vinyl acetate by photo-induced cobalt-mediated radical polymerization

Abstract

A degradable copolymer of 2-methylene-1,3-dioxepane (MDO) and vinyl acetate (VAc) was synthesized through photo-induced cobalt-mediated radical polymerization under UV irradiation (450 μW cm⁻² at 365 nm) at 30 °C by using (2,4,6-trimethylbenzoyl)diphenylphosphine oxide as an initiator and Co(acac)₂ as a regulating agent. Living polymerization behavior was proved via pseudo linear kinetics, the molecular weight of the copolymers increasing with conversion, narrow molecular weight distribution of copolymers and successful chain extension. The structure of the copolymer was characterized by NMR and MALDI-TOF MS. The reactivity ratios for MDO and VAc were determined to be r_MDO = 0.14 and r_VAc = 1.89. It was possible to vary the content of MDO in a wide range of copolymers by changing the feed ratio of VAc and MDO. The glass transition temperature increased gradually with increasing the amount of VAc. Such copolymers were easily degraded no matter in acidic or alkaline solution.