Studies Of Copolymerization Of CO₂ And Epoxy Propane Using Bifunctional SalenCo-X Catalytic System

Whether it is from the use of abundant carbon resources or from the perspective of carbon dioxide emission reduction,the fixation and utilization of carbon dioxide is a far-reaching research topic.Using epoxides and carbon dioxide as a monomer or a solvent can be copolymerized to prepare a biodegradable copolymer,aliphatic polycarbonate(PPC),which may partially replace polyolefin.Therefore,it is urgent to develop a new highly efficient and highly active catalytic system.According to the design rule of highly active bifunctional polymerization catalyst system proposed in related literature,this paper designed a electrophilic and nucleophilic two element bifunctional catalytic system consisting of SalenCo-X catalyst and quaternary ammonium salt of TBAB to catalyze the copolymerization of CO2 and PO.The following conclusions are drawn:(1)8 kinds of salen ligands had been synthesized and their structures were characterized by elemental analysis、FT-IR、MS、1H-NMR and melting point testing.(2)24 kinds of SalenCo-X complexes have been synthesized by combining 8 salen ligands with metal cobalt complexes with 3 axial groups(-Cl,-OPh(NO2)2,-NO3).And the successful coordination of metal was verified by FT-IR,elemental analysis,1H-NMR and UV-Vis.(3)The catalyst 3(C36H52CIN2O2Co)was applied to copolymerization of CO2 and PO And the effects of polymerization temperature,polymerization pressure,polymerization time and the proportion of monomers and catalysts on the catalytic activity were discussed in detail.The optimum reaction conditions are as follows:polymerization temperature is 50,CO2 pressure is 3.OMpa,nPO:nCat is 1500:1,and reaction time is 14h.(4)Under the optimized conditions,based on the results of copolymerization of 1-24 catalysts,the effects of different phenyl ring substituents,two amine backbone and axial groups on the catalytic performance were discussed.(5)The polymers were characterized by FT-IR、1H-NMR、13C NMR and TG.The results showed that the content of carbonate units in the polymer reached 100%,the head and tail of the polymer was connected 80%,the number average molecular weight reached 0.65×104g/mol,and the initial decomposition temperature of PPC was 185.6℃.