Glass transition and thermal softening of poly(phenylsilsesquioxane) particles prepared using two-step acid–base catalyzed sol–gel process

Spherical poly(phenylsilsesquioxane) (PhSiO 3/2 ) particles prepared using a two-step acid-base catalyzed sol-gel process had a 'core-shell' structure: their inside and outside parts were composed respectively of PhSiO 3/2 species with low and high molecular weights. The PhSiO 3/2 particles prepared using the two-step acid-base catalyzed sol-gel process exhibited two glass transition temperatures (Tg). The PhSiO 3/2 species in the inside of the particles showed glass transition behavior at a lower temperature than those in the outside of the particles, indicating that Tg is mainly dependent on the materials' respective molecular weights.