Synthesis and stimulus-responsive micellization of a well-defined H-shaped terpolymer

Abstract

We describe the synthesis and self-assembly of a well-defined H-shaped terpolymer in this paper. A block copolymer of poly(ethylene glycol) (PEG) and poly(N,N-dimethylaminoethyl methacrylate) (PDMA), which bears an azido group at the diblock junction (PEG–N₃(–PDMA)) was first prepared by atom transfer radical polymerization. Then, an alkynyl-terminated narrow distributed polytetrahydrofuran (PTHF-Alk) was synthesized as another building block via cationic ring opening polymerization. The well-defined H-shaped terpolymer was afforded by clicking PEG–N₃(–PDMA) onto both chain-ends of PTHF-Alk. This H-shaped terpolymer can self-assemble into micelles with different sizes and morphologies at various solution pH values. The micellar size also exhibits temperature-dependence at pH 7.4 and 9.2. The variation of size and morphology of the micelles with the solution pH and temperature is ascribed to the pH- and thermo-responsive properties of the PDMA block.