Heterotactic‐specific radical polymerization of N‐isopropylacrylamide and phase transition behavior of aqueous solution of heterotactic poly(N‐isopropylacrylamide) |
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| Authors: | Tomohiro Hirano Takahiro Kamikubo Yuya Okumura Yoichi Bando Ryosuke Yamaoka Takeshi Mori Koichi Ute |
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| Institution: | 1. Department of Chemical Science and Technology, Institute of Technology and Science, Tokushima University, Minamijosanjima 2‐1, Tokushima 770‐8506, Japan;2. Department of Applied Chemistry, Kyushu University, 744 Moto‐oka Nishi‐ku, Fukuoka 819‐0395, Japan |
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| Abstract: | Radical polymerization of N‐isopropylacrylamide (NIPAAm) in toluene at low temperatures, in the presence of fluorinated‐alcohols, produced heterotactic polymer comprising an alternating sequence of meso and racemo dyads. The heterotacticity reached 70% in triads when polymerization was carried out at ?40 °C using nonafluoro‐tert‐butanol as the added alcohol. NMR analysis revealed that formation of a 1:1 complex of NIPAAm and fluorinated‐alcohol through C?O···H? O hydrogen bonding induces the heterotactic specificity. A mechanism for the heterotactic‐specific polymerization is proposed. Examination of the phase transition behavior of aqueous solutions of heterotactic poly(NIPAAm) revealed that the hysteresis of the phase transition between the heating and cooling cycles depended on the average length of meso dyads in poly(NIPAAm). © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2539–2550, 2009 |
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| Keywords: | heterotactic hydrogen bonding N‐isopropylacrylamide radical polymerization stereospecific polymers stimuli‐sensitive polymers |
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