Synthesis And Application Of New Kind Of Catalysts For Olefin Polymerization And Research Of Design For Catalysts With Asymmetrical Structures

Polyolefin is a widely used polymer material,which is significant in improving its processing properties and polymer performance.Since 20th Century,numbers of research have been on the research and development of new polymerization catalysts.In the history of this research,adjusting the catalyst composition and structures has obtained a lot of practice and it can improve olefin polymerization activity and change polymer structures.In order to improve the processability of polymer materials,we need to add polar units to the polymer chain.However,because of the toxic effect of polar units on the catalyst,this process is very difficult to achieve.In recent years,most of the work has been focused on the development of a new type of catalyst that can bear strong polar functional group.In this paper,we synthesized a new class of ligands and their cationic palladium catalysts,which show excellent catalytic performance,and can achieve insertion of a variety of commonly used polar monomers.Secondly,we synthesized a kind of asymmetric diimine ligands and their palladium,nickel catalysts,whose influence on structures and properties of the polymer has been studied.1.First,we synthesized and characterized a series of palladium complexes containing phosphine phosphamide ligands,and studied their catalytic properties for olefin polymerization.This class of palladium catalysts showed high activity for olefin polymerization,generated polymers with much higher molecular weight than that of the phosphine sulfonic acid catalysts,and can achieve insertion of commonly industrial polar monomers with pretty high insertion ratio and molecular weight.2.Secondly,we synthesized and characterized a series of diimine palladium and nickel catalysts with asymmetric ligand structure,and studied their catalytic performance and physical and chemical properties of the polymers.For the nickel catalyst,some asymmetric ligands fixed on specific position,showed stereoselectivity in propylene polymerization.Other asymmetric catakysts can change structures generated the polymer with wide molecular weight distribution and good elasticity.The palladium catalyst does not show a wide distribution of molecular weight,and there is no special difference between the obtained polymer and the common structure.