One-pot terpolymerization of CO₂, cyclohexene oxide and maleic anhydride using a highly active heterogeneous double metal cyanide complex catalyst

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• 作者：Xue-Ke Sun ; Xing-Hong Zhang ; Shang Chen ; Bin-Yang Du ; Qi Wang ; Zhi-Qiang Fan ; Guo-Rong Qi
• 关键词：Carbon dioxide ; Double metal cyanide complex ; Terpolymerization
• 刊名：Polymer
• 出版年：2010
• 出版时间：12 November 2010
• 年：2010
• 卷：51
• 期：24
• 页码：5719-5725
• 全文大小：546 K

文摘

This paper describes a convenient one-pot terpolymerization of CO₂, cyclohexene oxide (CHO) and maleic anhydride (MAH) to afford a poly (ester-carbonate) with a low content of ether units (2.9–4.3 mol % ) using a highly active Zn–Co(III) double metal cyanide complex (DMCC) catalyst. Terpolymerization was carried out in tetrahydrofuran (THF) at 75–90 °C and 1.0–4.0 MPa and no cyclic carbonate was observed in NMR spectra. The number-average molecular weight (M_n) of the terpolymer was up to 14.1 kg/mol with a narrow molecular weight distribution of 1.4–1.7. The apparent efficiency of the catalyst was up to 12.7 kg polymer/g Zn, representing the highest catalytic activity for terpolymerization of CO₂, epoxides and cyclic anhydrides to date. THF dramatically inhibited polyether formation in this terpolymerization owing to its nucleophilicity towards the Zn²⁺ center of Zn–Co (III) DMCC. This presents the first example of solvent-assisted selectivity for inhibiting ether units in CO₂ polymerization catalyzed by a heterogeneous system. Kinetic analyses of MAH/CHO/CO₂ terpolymerization (MAH/CHO 0.2) suggested that polyester production was slightly faster than polycarbonate production in the early stage. A mechanism for this terpolymerization catalyzed by Zn–Co (III) DMCC catalyst was proposed. Moreover, addition of small amounts of MAH (MAH/CHO molar ratio ≤0.2) during CO₂/CHO copolymerization can improve the thermal properties of the resultant terpolymers.