Ring-opening Metathesis Polymerization Of Cycloolefin Catalyzed By Binuclear Vanadium Complexs

It is known that the distance and spatial position between the metals in binuclear complex catalyst have a significant influence on the catalytic ability in olefin polymerization.In this work,we design a series of binuclear vanadium complexes catalyst for ring-opening metathesis polymerization.In order to control the vanadium complex structure,we use different ligand structures to control the distance between two vanadium atoms,allowing the study of proximity effects between the two metals.We successfully designed and synthesized two kinds of binuclear vanadium complexes.One is binuclear vanadium dichloride(B1-B5).The bisphenol reagents with different framework structures was treated by lithiation and react with the existing vanadium trichloride complex according to the precise feed ratio.In the dinuclear complexes as catalyst precursor,under the action of alkyl aluminium cocatalyst,research on olefin polymerization(borneol and ethylene homopolymerization reaction),borneol in drop olefinic polymerization of polymers with controlled molecular weight and narrow molecular weight distribution and higher activity,in ethylene homopolymerization and and polar monomer copolymerization reaction not only keep higher activities,Moreover,it has higher insertion rate of polar monomer.In addition,the other part of this work is the synthesis of a binuclear vanadium dialkyl complexes(B6-B12).The dialkyl complexes can be obtained by selecting a series of bisphenol compounds with adjustable skeleton and reacting with vanadium trialkyl complexes.Addition of a certain amount of PMe₃at room temperature can promote the?-H elimination reaction to generate metal vanadium carbeen which could be the catalyst for ring-opening metathesis polymerization of cycloolefins.The catalytic activity of binuclear catalyst B6 was 7 times higher than that of monuclear catalyst,and the molecular weight distribution was narrower(monuclear PDI>2.0).Through detailed characterization of the polymer(DLS,GPC-MALLS,TG,AFM characterization),it was found that the generated polymer had a ring topological structure.We proposed the mechanism of chain reaction between binuclear catalysts.The formation of annular metal carbin is speculated.