Study On Epoxidized Liquid Polymer As Coupling Agents For Anionic Polymerization

In this thesis, linear liquid polybutadiene(PB), butadiene/styrene(B/S) tapered block, butadiene/styrene(B/S) pure block copolymer are synthesized by using the method of anionic polymerization. Star-like liquid PB, liquid B/S tapered block copolymer and liquid pure B/S block copolymer are synthesized by coupling reaction of there of living linear polymer with SiCl₄. The molecular weight , molecular weight distribution (polydispersity index) and microstructure are measured by GPC and IR. The polymers' polydispersity index (PD) are lower than 1.2 with the vinyl content at the range of 10～20%. In this thesis, the polymers above-mentioned are epoxidized by Formic acid- Hydrogen peroxide in-situ method with toluene as solvent, then epoxidized liquid polybutadiene(ELPB), star-like epoxidized liquid polybutadiene(star-ELPB), epoxidized liquid B/S copolymer(ELSB) are prepared. The epoxy value of their polymers are determined by ¹H-NMR and chemical titration.In this thesis, the rules of coupling reactions for butadiene homopolymerization and styrene homopolymerization in the presence of THF as initiator, cyclohexane as solvent, n-BuLi as initiator, epoxidized linear or star-like liquid butadiene/styrene polymers as coupling agent are discussed. The results show that: For butadiene homopolymerization, with the amount of epoxy group in ELPB increasing, coupling efficiency(CE) and average arm number increases, relatively arm number and polydispersity index decreases. With the amount of THF increasing, coupling efficiency decreases; With the increase of the time and temprature of coupling reaction, the coupling efficiency enhances. With star-ELPB as coupling agent, with the amount of epoxy group in star-ELPB increasing, coupling efficiency increases first then decreases later, across the peak, two kinds of coupling polymers are measured; the coupling efficiency reaches the maximum when THF/n-BuLi(molar ratio)=1. With ELSB as coupling agent, with the amount of epoxy group in ELSB increasing, coupling efficiency increases, and PD reaches the maximum when epoxy group/n-BuLi(molar ratio)=0.6. For styrene homopolymerization, with the amount of epoxy group in ELPB increasing, coupling efficiency increases till epoxy group/n-BuLi=0.8. With the amount of epoxy group in star-ELPB increasing, coupling efficiency increases first then decreases later; the coupling efficiency reaches the maximum when THF/n-BuLi(molar ratio)=1.