The Synthesis Of High Trans-1,4 Homopolymers And Random Copolymers Based On 1,3-pentadiene

The high trans-1,4-polydiene can be prepared with coordination catalysts or anionic polymerization initiators.The anionic polymerization has the characteristics of high polymerization activity,controllable molecular weigh t and molecular weight distribution.1,3-Pentadiene?PD?,isoprene?IP?and cyclopentadiene?CPD?are the key to the separation and utilization of petroleum cracking C5 resources,and PD has received little attention.Currently,the active controlled polymerization of PD cannot be achieved by coordination polymerization and cationic polymerization,which limits the further development and utilization of 1,3-pentadiene.The work of this thesis aims to explore the synthesis of high trans-1,4-poly?1,3-pentadiene?and a random copolymer of 1,3-pentadiene and styrene.The homopolymerization and random copolymerization mechanisms were also introduced based on the polymerization kinetic study and isomeric microstructure as well as sequence distributions analysis.The main results and conclusions are as follows:1.Under the binary regulator system of sodium dodecylbenzenesulfonate?SDBS?and tetrahydrofuran?THF?,ZP was initiated in cyclohexane solvent with n-butyllithium as initiator to obtain PZP,whose contents of trans-1,4-unit exceed75%,and the content of trans-1,4-unit can be controlled by changing the amount of SDBS.The actual molecular weight of the polymer is smaller than the designed molecular weight and the molecular weight distribution is wide??<2.0?;the SDBS has almost no effect on the microstructure of PEP.By ¹H NMR and quantitative ¹³C NMR analysis,the microstructure of PZP is mainly trans-1,4-structure,accounting for 75%⁸5%,the rest is 1,2-structure,no 3,4-structure exists.The sequence distribution is relatively regular,mainly in the head-to-tail connection mode,and the glass transition temperature is-35°C.The mechanism of polymerization is presumed by combining the conjugation effect of the terminal carbanion and double bond of the active species and the push-electron effect of the linking group.This mechanism explains the formation of the polymer microstructure reasonably.2.Using SDBS as a regulator,the 1,3-pentadiene?PD?and styrene?St?are mixed by monomer to synthesize PAP?including ZP and EP?copolymers using n-BuLi as an initiator in cyclohexane below 60°C.The results of GPC analysis indicated that the molecular weight distribution of EP/St copolymer?D<1.17?was narrower than that of ZP/St copolymer?D>1.20?in the presence of SDBS.The reason was that the polymerization mechanism of the isomer was different.The reactivity of the two monomers showed that the product of PD and St was a random copolymer in the presence of SDBS,the ZP/St copolymer was highly randomized and partial homopolymer segments existed in the EP/St copolymer.The ¹H NMR analysis of copolymer showed that the microstructure of poly?1,3-pentadiene?was mainly 1,4-units and the content of 1,2-units was extremely low.DSC analysis indicated that the random copolymer was a semi-crystalline polymer.Combined with PD/St copolymerization kinetics,monomer reactivity ratio and microstructure sequence analysis,the mechanism of copolymer polymerization were inferred that SDBS and n-BuLi formed a metal compound,which changed the polymerization mechanism of PD and St..3.Summarizing this article,we can find that the high trans-1,4-polypentadiene can be synthesized using SDBS as the regulator.This work includes a way to synthesize the random copolymer of 1,3-pentadiene and styrene using SDBS,and provides a new idea for the application of the poly?1,3-pentadiene?.