Synthesis Of SalenMCl Catalytic System And The Studies On The Copolymerization Of CO₂ And PO

A large number of carbon dioxide emissions have caused a series of environmental problems.And reducing the content of carbon dioxide has become the focus of attention of scientists.It has been found that many chemical products can be synthesized with carbon dioxide.The synthesis of biodegradable polycarbonate with carbon dioxide and epoxides has a broad application prospect.In this paper,6 kinds of Salen ligands were designed and synthesized by changing functional groups.The 24 kinds of SalenMCl catalysts were synthesized from the four ligands of iron,cobalt,manganese and aluminum by using the synthesized ligands as skeleton.They were characterized by FT-IR,1H-NMR,UV-Vis and elemental analysis,which proved that the synthesis of the ligands and catalysts was successful.The Salen catalysts were used to catalyze the copolymerization of CO2 and PO under the action of tetrabutylammonium bromide.The results showed that the SalenFeCl and SalenMnCl catalysts only got the cyclic carbonate.The SalenAlCl catalysts could got polycarbonate,but the selectivity were low.The catalytic activity of SalenCoCl catalysts were the highest,and the TOF reached 141 h-1.The effects of the reaction temperature,CO2 pressure,reaction time and the amount of catalyst on the copolymerization of CO2 and PO were investigated by using SalenCoCl catalyst.The optimum reaction conditions were as follows:the reaction temperature was 50?,the CO2 pressure was 3.0 Mpa,the reaction time was 12 h,and the molar ratio of PO to the catalyst was 1500:1.Under optimized conditions,the content of carbonate segment in the polymerization product was 99.9%,the content of connecting structure in head and tail(HT)was 74%,the molecular weight is 1.42×104,and the initial decomposition temperature was 178.3?.