The Synthesis And Catalysis Of Functional[ONXO](X=S,N) Binuclear Complexes In The Polymerization Of Epoxides

Polycarbonates have been used widely in the fields of electronic instruments,optics,medicine and the like.The ring-opening copolymerization of epoxide with CO₂ provides a low energy,green and environmentally friend route for the preparation of biodegradable polycarbonate.Therefore,to design and synthesis of a high efficiency and high selectivity of the catalytic system gradually become the focus of research in this field.Based on this,this paper were summarized as follows:?1?According to the design idea of"bimetallic coordination mechanism",[ONSO]Salen Ligand L₁ and[ONNO]Salen Ligand L₂ and three bimetallic complexes were synthesized.?2?The bimetallic complexes 1 and 2 were used as catalysts in ring-opening polymerization of epoxides,good catalytic activities were showed in the homopolymerization of epoxides for synthesizing polyethers.In the ring-opening polymerization of cyclohexene oxide,the homopolymerization of cyclohexene oxide?CHO?was catalyzed effectively by two kinds of complexes in the presence of phthalic anhydride?PA?,and the turnover frequency of cyclohexene oxide to products?TOF?value can be reached 152.70 h^-1.The reaction parameters,such as molar ratio,reaction time,temperature,and PA proportion were employed in order to study the influences on the polymeration activity using complexe 1.Under the condition of[CHO]:[PA]:[cat]=500:100:1?molar ratio?,the polymerization temperature was90°C and the reaction time was 1 h,the conversion of CHO reached 56%.?3?The bimetallic complex 3 assisted by ammonium salt were employed for the copolymerization of Propylene oxide?PO?and CO₂.Moreover,the effect of reaction conditions such as catalyst concentration,CO₂ pressure,polymerization temperature,reaction time,amount of cocatalyst on copolymerizationactivity,the carbonate linkage and molecular weight were systematically investigated.In the case of[PO]:[PPNCl]:[cat]=2000:2:1?molar ratio?,the polymerization temperature was 40°C,the polymerization reaction was 6 h,and the CO₂ pressure was 3.0 MPa,the conversion rate of PO was 39.43%,the TOF value was 131.43 h^-1,the product selectivity was 90.5%,the polymer had a molecular weight Mn of 17,100 and a PDI of 1.96.