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Controlled preparation of poly(ethylene glycol) and poly(L‐lactide) block copolymers in the presence of a monomer activator |
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| Authors: | Sang Hyo Lee Jae Min Oh Jin Soo Son Jung Won Lee Byung Soo Kim Gilson Khang Dong Keun Han Jae Ho Kim Hai Bang Lee Moon Suk Kim |
| Affiliation: | 1. Department of Molecular Science and Technology, Ajou University, Suwon 443‐759, Korea;2. Sang Hyo Lee and Jae Min Oh are equal first authors.;3. BK‐21 Polymer BIN Fusion Research Team, Chonbuk National University, 664‐14, Duckjin, Jeonju 561‐756, Korea;4. Fusion Biotechnology Research Center, Korea Research Institute of Chemical Technology, P.O. Box 107, Yuseong, Daejeon 305‐600, Korea;5. Biomaterials Research Center, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul 130‐650, Korea |
| Abstract: | Polymerization of L ‐lactide (LA) was performed in the presence of trifluoromethanesulfonic acid (CF3SO3H) via an activated monomer mechanism to synthesize various block copolymers composed of polyethyleneglycol (PEG) and poly(L ‐lactide) (PLLA). The PLLAs obtained had molecular weights close to theoretical values calculated from LA/PEG molar ratios and exhibited monomodal GPC curves. A 1H NMR spectroscopic study showed that the LA carbonyl carbon signal exhibited a change in chemical shift to lower field, caused by electron delocalization of the carbonyl carbon by CF3SO3H. We successfully prepared PEG and PLLA block copolymers using this activated monomer mechanism. We concluded that synthesis proceeded by LA ring‐opening polymerization caused by PEG in the presence of CF3SO3H to yield PEG and PLLA block copolymers. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5917–5922, 2009 |
| Keywords: | activated monomer mechanism biomaterials block copolymers poly(ethyleneglycol) poly(L‐lactide) ring‐opening polymerization trifluoromethanesulfonic acid |