On the hydrosilation of SBS and the properties of hybrid materials from hydrosilated SBS and silica

Abstract

Triethoxysilyl functionalized poly(styrene-b-butadiene-b-styrene) (TS-SBS) was prepared by the hydrosilation of carbon-carbon double bonds in a four-arm star SBS and was obtained by coupling the growing styrene-butadiene block copolymer with SiCl4 and with triethoxysilane in toluene at 70 °C using cis-bis(diethyl sulfide) platinum (II) dichloride (CPD) as a catalyst. The reactivity, in increasing order of hydrosilation, for these three kinds of double bonds was trans-1,4-< cis-1,4-< vinyl-. The molecular weight of TS-SBS decreased with time when it was heated with CPD in toluene at 70 °C. The gelation time of the sol-gel solution, TS-SBS/TEOS, was influenced significantly both by the molecular weight of and the attaching of the triethoxysilyl groups on the TS-SBS. After undergoing an in-situ sol-gel process, the TS-SBS/TEOS became an organic-inorganic hybrid material, TS-SBS/SiO2. The dynamic mechanical property and elongation of hybrids of the different molecular weights of TS-SBS and silica contents were studied in detail.