TEOS (tetraorthosilane) is a precursor for forming silica by releasing ethanol, a more precisely silsesquioxazine. Since the density of silica is much higher than polyurethane, it would increase the density of the material. The surface of those silica is full of surface silanol, which strongly hydrogen bonds to polyurethane molecules. Thus, in addition to the effect of nano fillers in polyurethane, the molecular confinement effect by the surface silanol hydrogen bonding to polyurethane reduces the flexibility of the polymer. The roughness increase can be both surface nanoparticle effect as well as the rheological effect, by the increased viscosity.

Thanks for your answer.@Hatsuo Ishida