Synthesis of polymethylene-b-poly(vinyl acetate) block copolymer via visible light induced radical polymerization and its application

Abstract

New well-defined amphiphilic polymethylene-b-poly(vinyl acetate) (PM-b-PVAc) diblock copolymers were synthesized via a tandem strategy combining polyhomologation of ylides, chain-end functionalization and a visible light induced degenerative iodine transfer polymerization using decacarbonyldimanganese (Mn₂(CO)₁₀). Firstly, an iodo terminated polymethylene (PM-I) was prepared by polyhomologation of ylides initiated by a new organic borane based on catecholborane followed by functional group transformation using iodine as the end-capping reagent. Then, a series of amphiphilic PM-b-PVAc diblock copolymers with controlled molecular weight (M_n = 5530–17 020 g mol⁻¹) and relatively narrow molecular weight distribution (Đ = 1.31–1.45) were obtained efficiently through a visible light induced degenerative iodine transfer polymerization of vinyl acetate (VAc) using PM-I as macroinitiator in the presence of Mn₂(CO)₁₀ under weak visible light irradiation at 40 °C. The micelles of such an amphiphilic diblock copolymer formed in tetrahydrofuran were observed by transmission electron microscopy (TEM). Moreover, the fabrication of porous films using PM-b-PVAc diblock copolymers via a static breath-figure process was investigated.