Iron-based Catalysts Catalyze The (co)polymerization Of Conjugated Diolefins

Nowadays,synthetic rubber as an alternative to natural rubber materials for manufacturing tire has attracted increasing attention.For this application,the synthetic rubber should processes wo essential properties:high wet-skid resistance and low rolling resistance,which are conflicting properties to be achieved.The styrene-butadiene rubber(SBR)is characterized of high wet-skid resistance and high rolling resistance,and the typical performance of cis-1,4 polybutadiene is good wearing resistant and low rolling resistance.Thus,it is a common way to blend polymers with corresponding properties for the industrial application.Vinyl rubber of high 1,2-content polybutadiene plays an important role in the synthetic rubber,which possesses properties such as good traction performance,high tensile strength,good tear resistance,low rolling resistance and relatively high wet-skid resistance as those of SBR.Iron catalytic system has attracted much attention in diene polymerization.for the particular properties as environmentally friendly,abundant raw materials sources,etc.However,the restriction of industrial application is the high melting point(Tm)of syndiotactic 1,2-polybutadiene obtained by iron catalytic system which is difficult to process.In this dissertation,the iron catalytic system has been used for the butadiene polymerization and butadiene/isoprene copolymerization.The main conclusion are summarized as follows:(1)The butadiene and isoprene copolymerization was carried out with iron(III)2-ethylhexanoate/triisobutylaluminum/diethyl phosphite(Fe(2-EHA)3/Al(i-Bu)3/DEP)catalytic systemwhich was effective in hexane at relatively high temperature of 50?.Copolymers with atactic 1,2-polybutadiene segment or syndiotactic 1,2-polybutadiene segment could be obtained by variations of the catalyst components.Tm value of the copolymer containing syndiotactic 1,2-polybutadiene segment was around 155?.Furthermore,the resultant copolymer was consisted with polybutadiene segments of high 1,2-unit content(51.1%)and polyisoprene segments of high 3,4-unit content(56.5%).(2)The butadiene homopolymerization w carried out with(Fe(2,EHA)3/[Al(i-Bu)3?AlEt3]/DEP)catalytic system at relatively high temperature of 50? in hexane.A series of 1,2-polybutadienes with adjustable 1,2-content were obtained by tuning the ratio of the AlEt3/Al(i-Bu)3,The GPC curve of obtained polybutadiene was unimodal which indicates the single site of the present catalytic system.The Tm value of polybutadiene was significantly decreased(from 168.7? to 123.2?)by increasing AlEt3 content.