Preparation Of Functionalized Polyolefins By Copolymerization Of Ethylene With Polar Monomers Catalyzed By Late-Transition Metal Catalysts

Since the advent of Drent catalysts,a large number of nickel and palladium catalysts based on phosphine-sulfonate ligands have been widely used in ethylene polymerization and ethylene copolymerization with a variety of polar monomers.In order to solve the problems of low activity and low molecular weight of copolymers in the copolymerization of ethylene with polar monomers,the key is to design and synthesize efficient catalysts or special functional monomers.After years of research,various strategies have been applied to the design of phosphine-sulfonate nickel and palladium catalysts.However,most of the reports are still focused on the simple modification of steric and electronic parameters of substituents on the P-atom of phosphine-sulfonate catalyst.In this thesis,we reasonably combine biaryl-or bulky aryl-group with bulky menthyl-substituent to design new phosphine-sulfonate nickel and palladium catalysts for the copolymerization of ethylene and polar monomers.In addition,the combination of three extensively utilized monomer feedstocks,ethylene?E?,1,3-butadiene?BD?,and carbon dioxide?CO₂?,into a polymer via the copolymerization is of great interest in both academia and industry.However,copolymerization for even two of them?E/BD,E/CO₂,BD/CO₂?is highly challenging,and E/BD/CO₂ terpolymerization remains unexplored.This reaction was achieved in an indirect manner by using a strategy for synthesizing special functional monomers.1.A class of ligands L1^L4 and the corresponding palladium complexes 1⁴{[?²?P,O?-?menthyl?ArP?C₆H₄SO₂O?]PdMe?pyr?}?1:Ar=2-?2',6'-?MeO?₂C₆H₃?C₆H₄;2:Ar=2-?C₆H₅?C₆H₄;3:Ar=2-?2',6'-F₂C₆H₃?C₆H₄;4:Ar=?MeO?₃C₆H₂?were synthesized and characterized.These palladium catalysts are used for ethylene polymerization to produce high molecular weight(up to 19.4×10⁴ g mol^-1)and highly linear polyethylene?methyl branches<1/1000 C?with a high activity as 3.3×10⁶ g mol^-1 h^-1.In the copolymerization of ethylene with acrylate,acrylic acid,acrylamide,vinyl ether,vinyl acetate,acrylonitrile and other challenging polar vinyl monomers,the better catalysts 3 and 4 afforded highly linear functionalized polyethylenes with clearly enhanced molecular weight,showing a significantly higher activity.In particular,when acrylate is copolymerized with ethylene,the catalytic activity and molecular weight of the copolymer are close to those in ethylene homopolymerization,which are up to 10⁶ g mol^-1 h^-1 and 10⁵ g mol^-1,respectively.2.A class of phosphine-sulfonate nickle complexes 1⁴{[?²?P,O?-?menthyl?ArP?C₆H₄SO₂O?]NiMe?pyr?}?1:Ar=?MeO?₃C₆H₂;2:Ar=2-?2',6'-?MeO?₂C₆H₃?C₆H₄;3:Ar=2-?C₆H₅?C₆H₄;4:Ar=2-?2',6'-F₂C₆H₃?C₆H₄?were synthesized and fully characterized.Among these nickel catalysts,1 and 4 are in favor of generating polyethylenes with high molecular weights in high activities and good thermal stabilities,while catalysts 2 and 3 suffer from low thermal stability.More remarkably,the preferred catalysts 1 and 4 also showed moderate to high activities for the copolymerization of ethylene with a broad scope of polar monomers,producing high molecular weights copolymers with relatively low incorporations.3.By using an allyl acrylate-type intermediate,the E/BD/CO₂ copolymerization was indirectly achieved for the first time with subsequent coordination-insertion copolymerization.These copolymerizations are regioselective?five-membered?-butyrolactone and six-membered?-valerolactone?,chemoselective?reactive acrylate and allyl ester,inert 1,2-disubsitituted acrylate?and stereoselective?different diastereomers?,and thus the copolymers are of highly novel microstructures bearing cyclicand noncyclic ester units in the main chain.