| The anionic polymerization regulator has the function of adjusting the polymerization rate and the microstructure of the product.The polymerization rate and the microstructures of polymerization products can be adjusted by adding different structural regulators or controlling the amount of the regulator.1,3-pentadiene(PD)is one of the three major components of the C5 fraction.Unlike the other two components that have achieved various polymerization methods,the PD polymerization method is limited to cationic polymerization and coordination polymerization.However,these polymerization methods are often accompanied by certain side reactions,and neither of which shows living controlled characteristic.Our laboratory has made preliminary efforts to find that anionic polymerization is a very effective method to achieve the activity polymerization of1,3-pentadiene.This paper describes the effect of new asymmetric structure regulator N,N-Dimethyltetrahydrofurfurylamine(DMTHFA)on the polymerization rate and product microstructure of 1,3-pentadiene and the random copolymers with butadiene(Bd)via living anionic polymerization.The main contents in this paper are as follows:(1)Under the regulator of DMTHFA,EP and ZP polymerization was initiated in the cyclohexane solvent with n-butyllithium(n-BuLi)as initiator to obtain PEP and PZP products,which main component is 1,4-structure accounting for 60%~65%,no 3,4-structure exists,and has a molecular weight distribution<1.51.The structural adjustment effect of DMTHFA on PD was obvious,when the DMTHFA/Li~+In the range of 0.1 to 1.0,with the increase of the ratio of DMTHFA/Li~+,the the content of 1,4-structure decreased and the1,2-structure increased.And the polymerization rate of PD in the DMTHFA regulator is greater than in the tetrahydrofuran(THF)regulator,and the glass transition temperature(T_g)of the PPD decreases as the amount of DMTHFA increases.Homogeneous activation energy of 1,3-pentadiene in DMTHFA regulator is Ea"(EP)>Ea"(ZP).Combined with the polymerization kinetic data and the push-electron effect at the end of the active species,the possible mechanism of living anionic polymerization was speculated,which rationally explained the formation of the polymer microstructure.(2)The anionic copolymerization of PD(EP and ZP)and BD was implemented under DMTHFA regulator with n-BuLi as initiator in the cyclohexane solvent,by one-step feeding method.Among the obtained P(PD/BD)products,PD is mainly composed of 1,4-structure,accounting for 52%~64%,no 3,4-structure,and BD is mainly composed of 1,2-structure,accounting for 35%~46%.The molecular weight distribution of P(EP/BD)(PDI<1.20)is narrower than that of P(ZP/BD)(PDI<1.43).The copolymer obtained by the reaction of EP and ZP with BD was a random copolymer in the presence of DMTHFA regulator,and the degree of randomization of P(EP/BD)was higher than that of P(ZP/BD),there is a partial homopolymer block in P(ZP/BD).The structural adjustment effect of DMFTA on P(PD/BD)was obvious,when the DMTHFA/Li~+In the range of 0.1 to 1.0,with the increase of the ratio of DMTHFA/Li~+,both PD and BD have a tendency of decrease in 1,4-structure and increase in 1,2-structure.The higher the content of BD in the feed,the lower the T_g of the copolymer.The copolymerization activation energy of 1,3-pentadiene and butadiene in DMTHFA regulator is Ea"(EP/BD)<Ea"(ZP/BD).The result of reactivity ratio experiments showed that P(EP/BD)and P(ZP/BD)are random copolymer,and the degree of randomization of P(EP/BD)was higher than that of P(ZP/BD),which contains a partial homoblock.The regulation of DMTHFA can accelerate the anionic polymerization rate of1,3-pentadiene and adjust the microstructure of the polymer.Expanding the complex regulation system of DMTHFA with other anion regulators has important research value.At the same time,the synthesis of random copolymer of 1,3-pentadiene with butadiene,that provides a new idea and theoretical basis for expanding the research and application of this monomer. |
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