A novel strategy for synthesis of amphiphilic π-shaped copolymers by RAFT polymerization

The amphiphilic π-shaped copolymers with narrow molecular weight distribution (Mw/Mn = 1.04–1.09) based on polystyrene (PSt) and poly(ethylene glycol) have been synthesized successfully. The reversible addition-fragmentation transfer (RAFT) polymerization of St in the presence of dibenzyl trithiocarbonate and N,N′-azobis(isobutyronitrile) (AIBN) yielded macro RAFT agent PSt–SC(double bond; length as m-dashS)S–PSt, subsequent reaction with excess maleic anhydride (MAh) at 80 °C in tetrahydrofuran afforded the PSt–MAh–SC(double bond; length as m-dashS)S–MAh–PSt. It was used as RAFT agent in the RAFT polymerization of St, and finally the amphiphilic π-shaped copolymers were obtained by the reaction of MAh with hydroxyl-terminated poly(ethylene glycol methyl ether) at 90 °C for 48 h. Their structures were confirmed by FT-IR and 1H NMR spectra, and their molecular weight and molecular weight distribution were measured by gel permeation chromatography.