The Synthesis And Chemical Modification Of 1,3-pentadiene Homopolymers And Its Copolymers Of Styrene

The conjugated diene polymers has been widely used for academic and industrialfields for its high strength,excellent elasticity properties,and fatigue resistance.However,the degradation and cross-linking,exposed to sunlight,ozone,were inevitable for the unsaturation of the carbon-carbon double bond presented in the polymers.Hydrogenation and bonding the polymers with a silicone polydimethylsiloxane(PDMS)could improve the properties.Combination of living anionic polymerization and hydrogenation reaction could prepare saturated olefin polymers with a controlled architecture and monodispersition.Meanwhile,polymers with special properties could be synthesized when bonding the conjugated diene polymers with a silicone polydimethylsiloxane(PDMS).These two modification methods has been an active field of research for a long time because of their superiority in chemical modification.In this papper,throughout noncatalytic hydrogenation reaction,a series of homopolymers of different microstructure content,random copolymer and alternating copolymer were hydrogenated by TSH in o-xylene.The reaction condition and the microstructure content were taken into account to investigated whether there was a effect or not.A series of polymer materials,which had new structure,were prepared.Block copolymer,containing polysiloxane segment was synthesized via living anionic polymerization.The main contents in this paper were as follows:(1)Homopolymers of different microstructure content were hydrogenated,when the hydrogenation degree reached up to 96%,non-strict ethylene-propylene alternating structure appeared in the hydrogenated pruducts.The effect of reaction condition on the extent of hydrogenation was investigated.It was found that the optimum ratio of TSH to C=C equaled to 4 of the polymers at 120? in o-xylene when the polymer content was 1%.The kinetic reaction of homopolymers was also investigated in this papper.The results obtained from 1HNMR indicated that the hydrogenation rate of microstructures was that:vinyl structure>1,4-unit.Meanwhile,the reaction followed a first order reaction related to double bonds within a certain period of time.(2)The controlled architecture copolymers of different hydrogenation degree were obtained using Poly(St-co-ZP)/Poly(St-co-EP)as hydrogenation substate.When hydrogenated the Poly(St-alt-ZP),the hydrogenation degree reached up to 95%,obtaining the alternating styrene-ethylene-propylene copolymer for the first time.The thermal stability and the chain flexibility of the polymers were improved,investigated by thermogravimetric analysis(TGA)and differential scanning calorimetry(DSC)measurements,respectively.(3)The P(St-alt-ZP)-b-PDMS and P(St-alt-EP)-b-PDMS with narrow molecular distribution wereprepared in cyclohexane/THF mixed solvents.After a complete conversion of equimolar ZP/EP and Styrene,single mole of D3 was added to the reactor.Two hours later,THF was added to the reactor,with formation of a cyclohexane/THF mixture,then a known amount of D3 was added to the reactor.The analysis of GPC on block copolymers indicated the deactivation of partly living chain ends due to the impurities in THF solvent and the second monomer.