Regio‐regular structure high molecular weight poly(propylene carbonate) by rare earth ternary catalyst and Lewis base cocatalyst |
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Authors: | Youhua Tao Xianhong Wang Xuesi Chen Xiaojiang Zhao Fosong Wang |
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Affiliation: | 1. State Key Laboratory of Polymer Physics and Chemistry, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun 130022, People's Republic of China;2. Graduate School of Chinese Academy of Sciences, Beijing 100039, People's Republic of China |
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Abstract: | Lewis base modification strategy on rare earth ternary catalyst was disclosed to enhance nucleophilic ability of active center during copolymerization of carbon dioxide and propylene oxide (PO), poly(propylene carbonate) (PPC) with H‐T linkages over 83%, and number–average molecular weight (Mn) up to 100 kg/mol was synthesized at room temperature using Y(CCl3OO)3‐ZnEt2‐glycerine catalyst and 1,10‐phenanthroline (PHEN) cocatalyst. Coordination of PHEN with active Zinc center enhanced the nucleophilic ability of the metal carbonate, which became more regio‐specific in attacking carbon in PO, leading to PPC with improved H‐T linkages. Moreover, the binding of PHEN to active Zinc center also raised the carbonate content of PPC to over 99%, whereas the PPC from common rare earth ternary catalyst was about 96%. Unlike the highly regio‐regular structure PPC but with relatively low molecular weight recently reported in the literature, our high molecular weight regio‐regular PPC did show significant improvement in thermal and mechanical performances. PPC with H‐T linkages up to 83.2% showed glass transition temperature (Tg) of 43.3 °C, while Tg of PPC with H‐T linkages of 69.7% was only 36.1 °C. When H‐T connectivity was raised from 69.7 to 83.2%, the modulus of PPC showed a 78% increase. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4451–4458, 2008 |
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Keywords: | biodegradable carbon dioxide copolymerization Lewis base polycarbonates poly(propylene carbonate) regio‐regular stereo‐specific polymers |
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