Emulsion copolymerization of styrene and butyl acrylate by reverse atom transfer radical polymerization

摘要

Reverse atom transfer radical copolymerization of styrene (St) and butyl acrylate was carried out in emulsion under normal emulsion conditions, using CuBr 2/bpy complex as catalyst. The effects of surfactant type, initiator type and concentration, and CuBr _2 addition on the system livingness, polymer molecular weight control, and latex stability were examined in detail. It was found that the Polysorbate 80 (Tween 80) and azodiisobutyronitrile gave the best exhibition in this system, polymer samples were got with narrow molecular-weight dispersity (M _w/M _n = 1.1-1.2) and linear relationships of molecular weight versus monomer conversion, as well as a relatively low polydispersity index (<0.1). Through the GPC and SEM analysis, the polymerization processes under these conditions showed good living/control characteristics relative to the processes under normal emulsion polymerization, although the latex stability was susceptible to the CuBr _2 catalyst.