A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene ...A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene carbonate）（PPC）. In the presence of ZnO/SiO_2, the ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst presented higher activity for CO_2/PO copolymerization, as well as a higher molecular weight of polycarbonate, while maintaining the high carbonate content originating from the neat ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst. In the presence of QASs bearing different halide anions（F., Cl., and Br.）, the type of the halide anion had a strong influence on the activity of the catalyst for CO_2/PO alternating copolymerization. Only tetramethylammonium fluoride（TMAF） could promote the alternating copolymerization without increasing the by-product. Combined the ZnO/SiO_2 catalyst and TMAF, the catalytic activity for CO_2/PO polymerization increased dramatically compared to the basic ternary catalyst system. The improved catalyst system produced a polymer with a high carbonate unit level equivalent to that of the polycarbonate produced by the basic ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst system.展开更多
基金supported by the Pujiang Talent Projects(16PJD016)~~
文摘A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene carbonate）（PPC）. In the presence of ZnO/SiO_2, the ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst presented higher activity for CO_2/PO copolymerization, as well as a higher molecular weight of polycarbonate, while maintaining the high carbonate content originating from the neat ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst. In the presence of QASs bearing different halide anions（F., Cl., and Br.）, the type of the halide anion had a strong influence on the activity of the catalyst for CO_2/PO alternating copolymerization. Only tetramethylammonium fluoride（TMAF） could promote the alternating copolymerization without increasing the by-product. Combined the ZnO/SiO_2 catalyst and TMAF, the catalytic activity for CO_2/PO polymerization increased dramatically compared to the basic ternary catalyst system. The improved catalyst system produced a polymer with a high carbonate unit level equivalent to that of the polycarbonate produced by the basic ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst system.
