Synthesis, characterization, and stimuli-sensitive properties of triblock copolymer poly(ethylene oxide)-b-poly(2-(diethylamino) ethyl methacrylate)-b-poly(N-isopropylacrylamide)

Well-defined triblock copolymer poly(ethylene oxide)-b-poly(2-(diethylamino)ethyl methacrylate)-b-poly (N-isopropyl-acrylamide) (PEO-b-PDNIAEMA-b-PNIPAAm) was synthesized via sequential reversible addition-fragmentation chain transfer polymerization (RAFT) of 2-(dimethylamino)ethyl methacrylate (DMAEMA) and N-isopropylacrylamide (NIPAAm) using alpha-methoxy-omega)-S-1-dodecyl-S-alpha-(alpha,alpha'-dimethyl-(alpha ''-acetate) poly(ethylene oxide) (mPEO-DDAT) as macro-RAFT agent, AIBN as initiator in dioxane at 80 degrees C. The polymerization data indicated that the both RAFT processes were well controlled. The molecular weights of macro-RAFT agents showed the influence on the RAFT polymerization process. The final PEO-b-PDMAEMA-b-PNIPAAm triblock copolymer can form uniform micelles in aqueous media above the lower critical solution temperature (LCST) due to containing temperature-sensitive PNIPAAm block. The micelle size and D-h were dependent on the composition of triblock copolymer and the pH value of the solution. The PEO-b-PDMAEMA-b-PNIPAAm triblock copolymer showed dual temperature and pH-sensitive property in aqueous media. (C) 2008 Wiley Periodicals, Inc.