Synthesis Of Polyolefin Catalysts And Functionalized Polyolefin

Olefins play a dominant role in the petroleum and chemical industries.As an important downstream industry of olefin industry,polyolefin plays a vital role in economic development and plays a decisive role in our daily life.Polyolefins have unique properties,such as high chemical stability,corrosion resistance,non-toxicity and low cost.Therefore,through the design and improvement of the structure of polyolefin catalysts,polyolefins with different structures have become the research focus in the field of olefin polymerization.Compared with other common polymers,polyolefins have lower LOI value(LOI of polyethylene is only～17.4),high flammability and poor fire resistance,which seriously restrict their applications in cable and other important fields.Therefore,it is very important and necessary to improve the flame retardancy of polyolefin materials.1.Firstly,a series of nickel catalysts with different phosphine oxide-imine structures were explored to catalyze the polymerization of ethylene.Unlike conventional polyolefin catalysts,the molecular weight of polyolefins obtained by catalysts with burdensome substituents in this system is much lower than that obtained by catalysts with ordinary substituents.Based on controlled experiments,theoretical calculations and literature evidence,we propose that the electronic effect plays a dominant role in the catalytic system compared with the steric effect.Traditional nickel catalysts for ethylene polymerization usually require a large number of cocatalysts such as MAO(methyl aluminoxane),which greatly limits its application in industry.However,this catalyst system does not need additional cocatalyst when catalyzing ethylene polymerization.2.A series of flame retardant polyolefins containing phosphine,silicon,boron and other chemical elements were synthesized using conventional phosphine-sulfonate palladium catalyst.The addition of these heteroatoms can effectively modulate the thermal,surface and mechanical properties of polyolefins,and more importantly,improve the flame retardancy of the materials largely.At the same time,we found that the functionalized polyolefin prepared by this method can greatly improve the compatibility of polyolefin and traditional flame retardant additives,thereby further increasing the flame retardant properties of polyolefin.