Study On The Synthesis Of Hydroxylated Copolyethylenes With Titanium-based Non-metallocene Catalysts And Ancillary Organic Ethers

Polyolefins have become the most widely used polymer materials in the world because of their low cost and excellent physical and chemical properties.However,the non-polarity of polyolefin materials limits its application in many fields.The introduction of polar functional groups into polyolefin molecular chains can impart many beneficial properties to the materials,such as adhesion,hydrophilicity,compatibility,etc.Synthesis of functionalized polyolefins by coordination polymerization is the most direct and atom-economical method,however,the Lewis acidic metal centers of traditional coordination polymerization catalysts are easily poisoned by Lewis basic polar functional groups,making them inactive.In addition,how to control the product form,avoid fouling,and make the production run stably is also a key challenge for the commercialized direct production of functionalized polyolefins.Based on these,four novel[N,P]bidentate Ti-based non-metallocene catalysts were contrived and synthesized,supplemented with organic ethers to achieve efficient copolymerization of ethylene/9-decen-1-ol,and obtained hydroxyl-functionalized polymer olefin,good effect of non-fouling.In this work,the effect of the type of substituents on the ligands on the catalytic performance of[N,P]bidentate Ti-based non-metallocene catalysts was investigated.It was found that the catalysts with electron-withdrawing substituents（F）on the ligands had better catalytic performance than those without substituents or catalysts with electron-donating substituents（CH₃）,which is contrary to the viewpoints of earlier researchers on other transition metal catalysts.The effects of aluminum-titanium ratio,polymerization temperature and polar monomer concentration on the catalytic performance were investigated under normal pressure（the ethylene pressure is 0.05 MPa）.When the temperature is 50℃and the amount of polar monomer is 2 m L（50 m L of toluene solvent）,it has higher activity,and the copolymer with excellent performance is obtained.Under these conditions,the difluoro-substituted catalyst Cat.D has the highest activity,reaching 5.32×10⁴g Polymer/（mol·Ti·h）,and the insertion rate of9-decen-1-ol in the obtained copolymer reaches 1.61 mol%.In the autoclave（the ethylene pressure is 0.8 MPa）,the polymerization process was optimized for the methods of catalyst activation,solvent purification and non-fouling.In the process of discussion,it was found that the ancillary compound of organic ether（C Donor,D Donor）can solve the problem of fouling.Through the optimized experimental technology,the effects of ligand substituents and polymerization temperature on the catalytic performance under these conditions were explored.Cat.D has better catalytic performance at 50℃,and its catalytic activity reaches 12.72×10⁵g Polymer/（mol·Ti·h）,the insertion rate of polar monomers in the obtained hydrophilic copolymer is 0.94 mol%,and avoids fouling during polymerization course.