Synthesis Of Novel Transition Metal Catalysts And Catalyzation For Norbornene (Co) Polymerization

The norbornene polymers are widely used in the fields of high-performance storage components,optical devices,packaging materials and biomedical materials and so on,because of their excellent properties such as high glass transition temperature,low water absorption and excellent photochemical properties.In order to improve the processability of the vinyl polynorbornene,the second monomers are often introduced to copolymerize with norbornene.Therefore,the development of new catalytic systems and copolymerization systems are a research hotspot in the field of norbornene polymerization.Compared with the conventional Ziegler-Natta catalyst,the?-diimine palladium catalyst and the ketimine metallocene catalyst are favored for their high catalytic activity and catalyst modification under mild reaction condition In this paper,a series of high-efficiency?-diimine palladium transition metal catalysts were designed and synthesized,and their polymerization behavior under different conditions was studied.On this basis,the metallocene catalysts were introduced to catalyze the norbornene derivative?ENB?containing a side chain double bond,and the influence of polymerization conditions on the polymerization reaction as well as the structure and properties of the polymer were investigated.The research content is as follows:In the first part,a series of symmetric bis?arylimino?acenaphthylenes Palladium?II?dichloride?-diimine complexes are designed and synthesized,and they are subjected to characterize by FT-IR,NMR and single crystal X-ray diffraction.On the activation with cocatalyst methylaluminoxane?MAO?and?C₆F₅?₄BC₆H₅NHC₂H₆,the norbornene is homopolymerized and obtains high catalytic activity,which is up to 4.45×10⁵g _PNBEmol_Pd^-1 h^-1,and the conversion rate can reach 94.7%.In addition,the catalyst still can 41.5%at 120oC.Moreover,the catalyst also exhibite excellent catalytic activity on copolymerization of NBE with ethylene,and the obtained copolymer is characterized by differential scanning calorimetry?DSC?and found to have the unique glass transition temperature T_g?T_g is up to 187oC?.In the second part,the titanium metallocene catalysts CpTiCl₂?N=C^tBu₂?[Cp=C₅H₅?1?,Cp'=^tBu C₅H₄?2?]are used to efficiently catalyze the copolymerization of ENB with ethylene and long-chain?-olefins,and the properties of the obtained copolymer are optimized and characterized.It catalyzes the activity of ENB with ethylene up to 3.20×10⁵kg-polymer/mol-Ti?h and the ENB and ethylene copolymers have the unique T_g?T_g is up to 140.7oC?,and the GPC test indicates that the molecular weight distribution of the obtained copolymers are related to the ENB monomer concentration;At the same time,comparing the obtained copolymers by Catalyst 1 and2,the ENB content of the two copolymers is similar,but the catalytic activity of Catalyst 2 is relatively higher.While the copolymers of ENB with long-chain?-olefins have high ENB content?up to 64.3 mol%?,and their molecular weight distribution is affected by steric hindrance and olefin chain length.In addition,for ENB and 1-hexene copolymerization,Catalyst 1 exhibits higher catalytic activity than Catalyst 2,and it also can obtain higher molecular weight copolymers.However,for ENB and 1-octene copolymerization,its catalytic activity and molecular weight of copolymer are relatively lower.