Tadpole-shaped amphiphilic copolymers prepared via RAFT polymerization and click reaction

The tadpole-shaped amphiphilic copolymers with cyclic polystyrene as the head and a linear poly(N-isopropylacrylamide) as the tail have been successfully synthesized by combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and click reaction. The synthesis involves two main steps: (1) preparation of a linear acetylene-terminated PNIPAAM-b-PS with a side azido group anchored at the junction between two blocks; (2) intramolecular cyclization reaction to produce the cyclic PS block using click chemistry under high dilution. The structures, molecular weights, and molecular weight distributions of the resulted intermediates and the target polymers were characterized by their H-1 NMR, FTIR, and gel permeation chromatography. The difference of surface property between tadpole-shaped polymer and its linear precursor was observed, and the water contact angles on the former surface are larger than that of the latter surface. (C) 2008 Wiley Periodicals, Inc.