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

Spherical poly(phenylsilsesquioxane) (PhSiO3/2) 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 PhSiO3/2 species with low and high molecular weights. The PhSiO3/2 particles prepared using the two-step acid–base catalyzed sol–gel process exhibited two glass transition temperatures (Tg). The PhSiO3/2 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.