Synthesis and self-assembly of amphiphilic gradient copolymer via RAFT emulsifier-free emulsion polymerization.
The amphiphilic gradient copolymers of 2,2,2-trifluoroethyl methacrylate (TFEMA) and acrylic acid (AA) have been synthesized by using amphiphilic RAFT agent via emulsifier-free emulsion polymerization with a starved feed method of adding TFEMA. Different cosolvents are added into polymerization system to inhibit AA's homopolymerization of in aqueous phase. RAFT polymerization kinetics under different reaction conditions are discussed in detail. (1)H NMR results indicate that the obtained copolymer has a chain structure with AA segments gradually changing to TFEMA segments. The copolymer latexes exhibit good pH stability (pH value from 5 to 14) and Ca(2+) stability. The self-assembly behavior of gradient copolymers in selective solvents are observed and studied by transmission electron microscopy. All the copolymers can form spherical micelles, but the homogeneity and size of micelles are different.
Department of Polymer Material and Engineering, School of Material Science and Engineering, Wuhan University of Technology, Wuhan, China. yanjunchen@whut.edu.cn
Yanjun
Y
Chen
Wen
W
Luo
Yifeng
Y
Wang
Chong
C
Sun
Mei
M
Han
Chaocan
C
Zhang