Synthesis, characterization, and self-assembly of amphiphilic fluorinated gradient copolymer

An amphiphilic copolymer of acrylic acid (AA) and 2,2,2-trifluoroethyl methacrylate (TFEMA) was synthesized by reversible addition-fragmentation transfer (RAFT) copolymerization, using a feed method for adding TFEMA. The kinetics of the RAFT copolymerization agreed well with those characteristic of a first-order reaction and the molecular weight of copolymers increased with the conversion increasing, both demonstrating that it proceeded in a controlled polymerization manner. Optimal copolymerization was achieved when the reaction was conducted at 70 degrees C, using a molar ratio of TFEMA : AA : RAFT agent : initiator of 400 : 400 : 4 : 1. Analysis of instantaneous H-1-NMR results proved that the obtained copolymer had a chain structure with AA segments gradually changing to TFEMA segments. The copolymer films had lower surface free energies and slightly microphase separation structures. The amphiphilic copolymer with gradient structures could self-assemble to form aggregates in selective solvents. The type and composition of solvent mixtures had great effects on the morphology and sizes of aggregates, which were investigated by transmission electron microscopy and dynamic light scattering, respectively. (c) 2012 Wiley Periodicals, Inc. J Appl Polym Sci. 127: 1485-1492, 2013