Preparation of Free-standing Films from 3-Mercaptopropylpolysilsesquioxane

3-Mercaptopropylpolysilsesquioxanes (poly-MTS) were synthesized by the stepwise hydrolytic polycondensation of 3-mercaptopropyl-(trimethoxy)silane (MTS) in the presence of hydrochloric acid as a catalyst in a nitrogen stream. Poly-MTS was mainly composed of the silsesquioxane structure with an average formula (HS(CH2)3Si(O3/2))n. The content of silsesquioxane structure in the polymer increased with increasing water content. A transparent free-standing film was prepared by heating a tetrahydrofuran solution of poly-MTS for 14 d at 80°C.