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Precise synthesis of sulfur-containing polymers via cooperative dual organocatalysts with high activity  
Precise synthesis of sulfur-containing polymers via cooperative dual organocatalysts with high activity
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關鍵詞: Metal-free  carbonyl  sulfide  100%  alternating  degree  
資料大?。?/td> 1177k
所屬學科: 高分子化學
來源: 來源網絡
簡介:
Metal-free and controlled synthesis of sulfur-containing polymer is still a big challenge in polymer chemistry. Here, we report a metal-free, living copolymerization of carbonyl sulfide (COS) with epoxides via the cooperative catalysis of organic Lewis pairs including bases (e.g.: phosphazene, amidine, and guanidine) and thioureas as hydrogen-bond donors, afford welldefined poly(monothiocarbonate)s with 100% alternating degree, >99% tail-to-head content, controlled molecular weights (up to 98.4 kg/mol), and narrow molecular weight distributions (1.13–1.23). The effect of the types of Lewis pairs on the copolymerization of COS with several epoxides is investigated. The turnover frequencies (TOFs) of these Lewis pairs are as high as 112 h?1 at 25 °C. Kinetic and mechanistic results suggest that the supramolecular specific recognition of thiourea to epoxide and base to COS promote the copolymerization cooperatively. This strategy provides commercially available Lewis pairs for metal-free synthesis of sulfur-containing polymers with precise structure.
上傳人: xhzhang
上傳時間: 2019-04-02 14:48:31
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