Preparation Of Functionalized Polyethylene Based On Late Transition Metal Catalyst

Polyolefin materials are widely used in food packaging,medical and health,machinery,military,automobile manufacturing and other applications due to their excellent chemical resistance and excellent mechanical properties.However,as people's requirements for material performance increase,single polyolefin materials can no longer be applied to more application fields,so the functionalization of polyolefins is particularly important.Functionalized polyolefins can significantly improve the adhesion,coloring,surface properties,solvent resistance,rheological properties,blending properties,etc.of the material,which is of great significance for expanding the application of polyolefins in other fields.This paper mainly studies the scientific problems of preparing functionalized polyolefin materials with late transition metal catalysts.Through the design and selection of suitable catalysts,a series of functional polyolefin materials have been synthesized,mainly including the following three aspects:1.The degree of branching,molecular weight and molecular weight distribution are important parameters for determining the properties of polyolefin materials.In order to conveniently adjust these parameters,a series of 2-imino-pyridine-N-oxide nickel complexes were designed and synthesized and studied They have the ability to catalyze the polymerization of ethylene and copolymerize with methyl 10-undecylenate.These catalysts can show very high activity(up to 107 g PE mol Ni-1 h-1)under the action of a small amount of co-catalyst in the ethylene polymerization process.By adjusting the structure of the catalyst and polymerization conditions,the molecular weight,molecular weight distribution,melting point and branching degree of polyethylene can be easily adjusted,and the mechanical properties and rheological behavior of bimodal polyethylene can be studied at the same time.2.We prepared a polar functionalized polyolefin material that is cross-linkable,self-repairing and photo-responsive.Phosphine sulfonic acid palladium catalyzed the ternary polymerization of ethylene to prepare polyolefin with carboxylic acid and cyclic structure.The inserted cyclic monomer can effectively adjust the crystallinity and elasticity of the polymer,and the more than double bonds of the cyclic monomer can provide cross-linking points.The subsequent introduction of Fe3+/citric acid and polymer carboxylic acid can induce dynamic crosslinking and achieve self-repair performance.In the presence of citric acid and under ultraviolet irradiation,Fe3+ can be reduced to Fe2+,while Fe2+ can be easily oxidized to Fe3+.This photoreduction and thermal oxidation strategy provides a new and effective way to recover thermoset polymers.The interaction of these parameters makes the system highly versatile and may be applicable to other types of polymer materials.3.Finally,based on the late transition palladium catalyst catalyzed by the copolymerization of ethylene and polar monomers,we synthesize polyolefins with intrinsic antibacterial properties through three different ways.First,palladium phosphorous sulfonate catalyzed the direct copolymerization of ethylene and nitrogen-containing comonomers to prepare nitrogen-functionalized polyolefins with certain antibacterial properties.Subsequently,the pre-synthesized chlorine and carboxyl functional group polymer undergoes functional group conversion reaction to form two types of antibacterial polyolefins functionalized with imidazolium and metal ions.This type of antibacterial polyolefin material has high molecular weight and high polar functional group content,and has excellent properties.These functionalized polyolefins can also be used as effective compatibilizers for non-polar polyolefins with polar antimicrobial agents.