The Synthesis Of Homopolymers And Random Copolymers Based On 1,3-pentadiene And ?-methylstyrene

1,3-pentadiene,as the isoprene's isomer,is a conjugated diene extracted from carbon five fractions,however the physical and chemical properties of 1,3-pentadiene are different from isoprene(Ip)?butadiene(Bd).Currently,1,3-pentadiene polymer are usually synthesized via stereospecific coordination polymerization or cationic polymerization which is different from isoprene mature polymerization method and all above methods exist hydrogen transfer and isomerization and double bond cyclization reactions,then,neither of which shows living controlled characteristic.Therefore,the lack of polymerization methods limits the development and utilization of 1,3-pentadiene.In addition,it is found that random copolymers can be synthesized from 1,3-pentadiene(including(Z)-1,3-pentadiene and(E)-1,3-pentadiene)and alpha methylstyrene,those copolymers has high potential applications in mang fields with special structure and properties.This paper describes the homopolymerization of 1,3-pentadiene and the random copolymers and cyclization copolymer,which are based on copolymerization of 1,3-pentadiene with alpha methylstyrene via living anionic polymerization.The main contents in this paper are as follows:1 · On the basis of obtaining polymer grade PD isomers(including ZP and EP),the anionic polymerization of PD isomers with n-BuLi as initiator and DTHFP as regulator is carried out in hydrocarbon solvent.It was observed that the polymerization of EP shows living and controlled characteristic and the resulting homopolymer(PEP)with much narrow molecular weight distributions(MWD)(D<1.20)and predicted molecular weights were obtained:while the molecular weight distributions of poly(ZP)is broad MWD(D>1.40)for the reason that the rate of propagation relatively faster than the rate of initiation.The microstructure of homopolymer(PEP and PZP)were characterized by 1H NMR and 13C NMR analysis,finally,an interpretation for poly(1,3-pentadiene)is proposed considering the conjugative effect of adjacent double bond as well as electron-donating effect.2.On the basis of the controllable polymerization of 1,3-pentadiene,the monomer alpha methylstyrene(AMS)with excellent thermal stability is introduced,the anionic copolymerization with DTHFP as the additive and n-butyllithium as initiator is carried out in cyclohexane solvent.Under 50 ?,we synthesize the copolymer PAP with designed molecular weight and relatively narrow molecular weight distribution.At the same time,we also investigate the kinetics and the activation energy of copolymerization.The analysis of GPC shows that EP monomer exihibt better than ZP in the controlled copolymerization of AMS,because of ZP with rigid planar structure than EP,and then compared with ZP,the molecular weight distribution of EP shows narrow.The results of DSC reveals that the two copolymers have a glass transition temperature,and the glass transition temperature is suitable,it can be concluded that the copolymers have good potential application value in the field of plastic additives,additives and so on.3.The random copolymer with certain degree of cyclization can be obtained using Lewis acid CF3SO3H as catalyst on the basis of the obtained EP and AMS random copolymer.1H NMR shows that the introduction of Lewis acid reduce the number of double bond in the copolymer,the reason is that intramolecular cyclization reaction,TGA and DSC analysis show that with the increase of cyclization degree,thermal stability of polymer improves continuously,for the reason that the intramolecular cyclization reaction make the polymer chain more rigidity and reduce the mobility of the polymer chain,leading to the improvement of the heat resistance.4.From summarizing the research results of this thesis,it is indicated that the copolymerization of 1,3-pentadiene are much different than that of butadiene or isoprene.The synthesis of copolymers with 1,3-pentadiene and alpha methylstyrene and cyclization random copolymers provides new ideas and theoretical reasons for the research and application development of 1,3-pentadiene.