Synthesis Of Functionalized Polyolefin Through Co(ter)polymerization Of Ethylene And Polar Monomers

Polyolefins have enormous annual production and diverse applications as plastics,fibers and elastomers.The non-polar nature of polyolefins represents one of their biggest limitations.The introduction of some polar functional groups could greatly improve their many properties and further expand their applications.Late transition metal catalysts have achieved great success in the area of ethylene copolymerization with polar monomers.Through catalyst modifications,it is possible to finely control the polymer micro structures.In this work,we focused on the synthesis of functionalised polyolefins,and the effects of the microstructures and polar monomes on the properties of materials.We used a phosphine-sulfonate-palladium catalyst and two specially designed ?-diimine palladium catalysts to synthesize a series of functionalised polyolefins.The dissertation includes following three parts:1.First,ethylene copolymerization and terpolymerization reactions with some nitrogen-containing monomers were investigated using ?-diimine palladium and phosphine-sulfonate palladium catalysts.In the ?-diimine palladium system,ligand sterics plays an important role and sterically open ligands lead to much better comonomer incorporation.The phosphine-sulfonate palladium catalysts showed much better activities and higher copolymer molecular weights.Copolymers and terpolymers with high molecular weights but significantly different microstructures were obtained in these two systems.The incorporation of polar functionalized comonomers could significantly improve the surface properties of the resulting polymeric products.The water contact angle of pure polyethylene could be reduced from above 100° to ca.80°.In addition,the mechanical properties of the polyolefins could be modulated by the introduction of these polar monomers2.Then,we used the different features between phosphine-sulfonate-palladium catalyst and ?-diimine palladium catalyst to synthesize a series of P-LLDPE and P-LDPE analogues.We demonstrate this possibility through palladium-catalyzed ethylene copolymerizations with polar-functionalized ?-olefins and their terpolymerizations with ?-olefins.A phosphine-sulfonate-palladium catalyst(PO-Pd)afforded highly linear polyethylene during ethylene homopolymerization.Linear low-density polyethylene(LLDPE)was obtained from the PO-Pd-catalyzed copolymerizations of ethylene with ?-olefins;in these copolymerizations,the partial or complete replacement of ?-olefins with po lar-functional ized ?-olefins led to the formation of polar-functionalized LLDPE(P-LLDPE).A specially designed ?-diimine palladium catalyst(NN-Pd*)afforded polyethylenes with tunable branching densities(16-37 per 1000 carbon atoms),melting points(101-113?),and densities(0.89-0.92 g/cm3),which closely resemble those of low-density polyethylene(LDPE).The NN-Pd-catalyzed copolymerizations of ethylene with polar ?-olefins generated analogues of polar-functionalized low-density polyethylene(P-LDPE).The mechanical and surface properties of these polar polyolefin materials were studied in detail,and their properties were further improved/modified through cross-linking reactions.3.Finally,we used a phosphine-sulfonate-palladium catalyst to synthesize a new type multi-functionalized polyolefin through using bio-resourced comonomers eugenol.Utilizing bio-resourced comonomers for the generation of high-performance polyolefin materials is attractive from a sustainable point of view.In this contribution,some bio-resourced eugenol and related comonomers were incorporated into polyolefins through palladium catalyzed copolymerization and terpolymerization reactions.Importantly,high molecular weight catechol functionalized polyolefins can be generated.The introduction of different metal ions can induce efficient interactions with the incorporated catechol groups,leading to enhanced mechanical properties and self-healing properties.Moreover,catechol functionality can greatly improve other properties such as surface properties,adhesion properties,and compatibilizing properties.