Copolymerization Of Ethylene With Functional Olefins By Half-Sandwich Scandium Complexes

Functionalized polyethylene materials keep the advantage of low density, good stability and low price of polyethylene materials and enhance the flexibility, adhesion, surface properties and with other polymers miscibility etc., particularly offer excellent photoelectric, medical and ion exchange new application. At present, the research focus on the synthesis of functional polyethylene is the direct copolymerization of ethylene with functional olefins. In this thesis, the relationship between catalyst structure and catalytic properties in the copolymerization of ethylene with functional a-olefin or functional styrene derivatives by half-sandwich scandium complexes were investigated. The copolymerization of ethylene and functional olefins was achieved, to afford a series of novel functionalized polyethylene.1. In the copolymerization of ethylene with functional a-olefin by use of half-sandwich scandium complexes, lewis base THF ligand in the scandium complexes, the polarity of functional groups and the distance of functional group and double bond affected copolymerization activity and functional monomer incorporation. In the copolymerization of ethylene with ?-bromo-a-alkenes, the double bond gave priority to the bromine atom to coordinate with scandium metal. At 1.01×105 Pa of ethylene (Et) pressure, the copolymerization of ethylene with 10-bromo-l-decene (BrDC) was realized by using (C5Me4SiMe3)Sc(CH2SiMe3)2(THF) (Sc-THF) bearing THF ligand, to afford Et-BrDC copolymer (Mn=7.1×104, Mw/Mn=1.43) containing 12 mol% BrDC units. The long chain comonomer BrDC showed higher copolymerization activity than short chain 6-bromo-l-hexene (BrHX). In the copolymerization of ethylene with ?-amino-?-alkenes, the nitrogen atom gave priority to double bond to coordinate with scandium metal. The copolymerization of ethylene with 5-(N,N-diethylamino)-1-pentene (DEAP) without protecting group was realized by using (C5Me4SiMe3)Sc(CH2C6H4NMe2-o)2(Sc-Free) without THF ligand, to afford Et-DEAP copolymer containing 26 mol% DEAP units. The short chain comonomer DEAP showed higher copolymerization activity than long chain 10-(N,N-diethylamino)-1-decene(DEAD).2. In copolymerization of ethylene with functional styrene derivatives founded, the electronegativity of substituted group had greater impact on the activity and selectivity. By use of scandium catalysts Sc-THF and Sc-Free, the copolymerization of styrene derivatives containing electron-donating groups (CH3, SiH (CH3) 2, N (CH3)2) with ethylene at 1.01×105 Pa were achieved, to afford a family of multi-block copolymers with syndiotactic poly(p-methylstyrene) blocks or syndiotatic poly(p-vinylphenyldimethylsilane) blocks or syndiotatic poly(p-(N,N-dimethyl)styrene) blocks, the copolymerization activity was up to 106 g of polymer (mol of Sc)-1 h-1, the content of styrene derivatives in copolymers can be controlled between 10 mol%-40 mol%. The copolymerization of styrene derivatives containing electron-withdrawing group (Cl) with ethylene was achieved, to afford multi-block copolymers with syndiotactic poly(p-chlorostyrene) blocks by using Sc-THF, the copolymerization of p-chlorostyrene with ethylene was achieved to a multi-block copolymer with atactic poly(p-chlorostyrene) blocks by using Sc-Free.