Molecular Structure Design And Hydrogenation Of Star-shaped Polybutadiene-based Polymers

Star graft polymers are widely used because of their special structure and properties.Therefore,the synthesis of polybutadiene-based polymers based on star graft structure has important research significance.Firstly,the star graft high 1,2-structure polybutadiene(S-g-PB)and the star graft styrene-butadiene copolymer(S-g-SBS)with ordered polystyrene as side chains were designed and synthesized by living anionic polymerization and coupling modification technology,using tetrahydrofuran(THF),ethyl tetrahydrofurfuryl ether(ETE)and 2,2-di(2-tetrahydrofuryl)propane(DTHFP)as structure regulator,divinyl benzene(DVB)as coupling agent.Moreover,the unsaturated double bonds in the PB segment of S-g-PB and S-g-SBS were selective hydrogenated using the system of p-toluenesulfonyl hydrazide(TSH)/tri-n-propylamine(TPA)to generate the corresponding hydrogenated products,S-g-H-PB and S-g-SEBS.The chemical structures,molecular weight and molecular weight distribution,as well as hydrogenation degree of hydrogenated products were characterized by proton nuclear magnetic resonance spectroscopy(~1H-NMR),fourier transform infrared spectroscopy(FT-IR)and gel permeation chromatography(GPC).The thermal and mechanical performances of star graft polymers before and after hydrogenation were studied by differential scanning calorimetry(DSC)and thermogravimetric analysis(TGA),and the application of hydrogenated products in refined oil modifiers was explored.The results showed that S-g-PB with controlled molecular weight and over 70%the content of 1,2-structure was obtained.The content of 1,2-structure of polybutadiene in S-g-SBS could be regulated between 30%and 70%,and the lower the 1,2-structure and bound styrene content,the lower the melt viscosity and the glass transition temperature(Tg).The melt viscosity of S-g-SBS was obviously lower than that of linear SBS under the same condition.The TSH/TPA system could be used for efficient hydrogenation of S-g-PB and S-g-SBS,S-g-H-PB with hydrogenation degree could reach more than 95%,S-g-SEBS with hydrogenation degree could reach more than 98%.Hydrogenation reaction can improve their thermal property obviously,and the hydrogenated product has a certain effect on the modification of refined oil.