Synthesis Of In-Chain Functionalized Polyethylene Containing Si-H Reactivity Group

In-chain functionalized polyethylene containing reactivity group, synthesized by living anionic polymerization method, has broad prospects and application research value due to its narrow molecular weight distribution, controllable structure and achievable functionalization.In this dissertation, the monomer with Si-H reactivity group:4-vinylbenzyl dimethyl silicane(VPDMS) was synthesized via Grignard reaction. Anionic copolymerization of butadiene and VPDMS was implemented with the mole ratio of100/1,75/1,50/1,25/1, respectively, using cyclohexane as solvent and n-butylithium as initiator. The molecular weight and micro-structure were characterized by GPC, FT-IR and1H-NMR measurements. The butadiene/VPDMS copolymer was hydrogenated by p-toluenesulfonyl hydrazide (TSH) and tripropylamine under atmospheric pressure and polyethylene containing Si-H group was prepared. Subsequently, the hydrosilation reaction polyethylene containing silicon-hydrogen group with N, N-dimethyl acrylamide and acrylonitrile was preformed respectively. Consequently, amide-group functionalized and cyano-group functionalized polyethylene were synthesized. The molecular parameters of the polyethylene containing Si-H group and amide-group functionalized and cyano-group functionalized polyethylene were investigated by IR and1H-NMR. The crystallization properties and thermal properties of functionalized polyethylene compared with linear low density polyethylene(LLDPE) were explored by DSC and TGA analysis measurements.The characterization of butadiene/VPDMS copolymers indicated that:the molecular weight distribution of copolymers were less than1.2and the1,2-structure content of butadiene units were approximated to7.0%. The characterization of hydrogenation products of copolymers showed that the Si-H group had no effect on the hydrogenation of copolymers using this catalyst system and the hydrogenation degree approached100%without side reactions. DSC analysis demonstrated that the degree of crystallinity and the melting point of the functionalized polyethylene samples reduced compared with LLDPE. TGA analysis demonstrated that the thermal stability of the functionalized polyethylene enhanced compared with LLDPE. Hydrosilation reactions had been performed on different substrate (polyethylene containing different amount of Si-H group). The characterization results indicated that the melting point were lower with respect to the functionalized polyethylene with functional group being introduced. It is suggested that the properties of the functionalized polyethylene can be modified by the amount of reactivity group introduced.