Anionic Polymerization Of Piperylene And Microstructure Control Of Piperylene Products

1,3-pentadiene(PD)is an important diene in C5 resources of petroleum cracking.The microstructure of polydiene has a significant impact on its product properties,so it has important research value on the microstructure control of poly(1,3-pentadiene).In this thesis,the effects of several new tetrahydrofuran-based regulators,the novel dilithium initiator and styrene comonomers on the polymerization of 1,3-pentadiene were investigated in detail by anionic polymerization method.The main research conclusions are as follows:(1)The polymerization of 1,3-pentadiene was initiated by n-butyllithium in cyclopentane solvent,and the effects of the novel tetrahydrofuran-based polar modifier on the polymerization kinetics and microstructure were studied.The regulation effect of anionic polymerization rate and microstructure indicated that the tetrahydrofurfuryl ethyl ether(ETE)was better than tetrahydrofurfuryl butyl ether(BTE)and tetrahydrofurfuryl benzyl ether(BYLTE).Moreover,when the ETE/Li ratio increased up to 0.5,the 1,2-structure content of poly(1,3-pentadiene)increased from 14.1%to 34.8%,but the molecular weight distribution decreased from 1.36 to1.18.On the other hand,the three types of double chelate ether-amine regulators had the following effects on the polymerization rate and microstructure of piperylene:N,N-dimethyltetrahydrofurfurylamine(DMTHFA)>N-tetrahydrofurfuryl pyrrole(THFP)>N-tetrahydrofurfuryl piperidine(THFHP).When DMTHFA/Li=0.5,the content of poly(1,3-pentadiene)1,2-structure can be reached up to 35.9%,and the molecular weight distribution can be increased from 1.36 down to 1.20.(2)The novel dilithium initiator Li-X-Li(containing THF/Li=1.5)was used to investigate its effect on the polymerization of 1,3-pentadiene in a cyclopentane system.The results showed that the self-made new dilithium initiator had good stability and high initiation activity,and can greatly improve the PD polymerization rate.The polymerization process conformed to the first-order kinetic equation,and the polymerization activity was well controllable((?)<1.20).In the PD/IP copolymerization system,the increase of the IP ratio significantly increases the reaction rate.Comparing three types of dichelate cyclic ether regulators with different carbon chain lengths(tetrahydrofuran ethyl ether(ETE),tetrahydrofurfuryl amyl ether(ATE),tetrahydrofurfuryl hexyl ether(HTE)),it was found that ETE had a better effect on regulating the polymerization rate and microstructure.When ETE/Li=0.2,The degree of branching in the polymer increased from 26.7%to 32.5%.By comparing with N-tetrahydrofurfurylpyrrole(THFP),ditetrahydrofurfuryl propane(DTHFP)and N,N-dimethyltetrahydrofurfurylamine(DMTHFA),it was observed that DMTHFA was better than others.When DMTHFA/Li=0.2,the degree of branching in the polymer increased from 26.7%to 40.8%.Polypipene copolymers with higher branched structure content can be obtained by using IP copolymerization strategy and novel tetrahydrofuran-based modifiers.(3)Based on the special binary-alternating strategy of 1,3-pentadiene,the kinetics and microstructure of the ternary polymerization of 1,3-pentadiene(PD)/styrene(St)/1,1-diphenylethylene(DPE)were investigated systematically.The effects of comonomer ratio and polymerization temperature on terpolymerization were investigated.The results show that the alternating structural units A[St|PD],B[DPE|PD],C[St|DPE]can be regarded as the monomers in the copolymerization,and can be embedded into the terpolymer according to the difference of the copolymerization activity.The E_avalue was determined by kinetic experiments:A/B>B/C>A/C copolymerization system,NMR data verified that styrene monomer and 1,3-pentadiene microblock in the terpolymer were suppressed,and the overall degree of alternation was much high,also the 1,4-structure content of piperylene exceeded 90%.DSC results show that the glass transition temperature(T_g)of terpolymers can be controlled by the ratio of comonomers,and GPC data show that the terpolymerization process has obvious living-controlled characteristics(molecular weight can be designed andD<1.12).