Constructing semi-fluorinated PDEAEMA-b-PBTFVBP-b-PDEAEMA amphiphilic triblock copolymer via successive thermal step-growth cycloaddition polymerization and ATRP

Abstract

A series of amphiphilic perfluorocyclobutyl-containing ABA triblock copolymers, PDEAEMA-b-PBTFVBP-b-PDEAEMA (DEAEMA: 2-(diethylamino)ethyl methacrylate; BTFVBP: 4,4′-bis(1,2,2-trifluorovinyloxy)biphenyl), was synthesized through the site transformation strategy, combining thermal step-growth cycloaddition polymerization of BTFVBP and atom transfer radical polymerization (ATRP) of DEAEMA. A BTFVBP trifluorovinyl aryl ether monomer was first thermally polymerized to form a semi-fluorinated perfluorocyclobutyl aryl ether-based segment, followed by end functionalization for preparing a Br-PBTFVBP-Br macroinitiator bearing one ATRP initiating group at each end. ATRP of DEAEMA was initiated by Br-PBTFVBP-Br to afford four PDEAEMA-b-PBTFVBP-b-PDEAEMA triblock copolymers with relatively narrow molecular weight distributions (M_w/M_n ≤ 1.42) via varying the feeding ratio of DEAEMA to the macroinitiator. The critical micelle concentration (cmc) of the obtained amphiphilic triblock copolymers was determined by fluorescence spectroscopy using N-phenyl-1-naphthylamine as a probe. Micellar morphologies were investigated by transmission electron microscopy. It was shown that such triblock copolymers could self-assemble into large compound micelles, vesicles, and bowl-shaped micelles in aqueous solution with different initial water contents and compositions.