Phase transformation of titania domains in the titania/PDMS hybrid particles by heat treatment

Thermal transformation of a previously reported spherical titania/PDMS hybrid particles (J. Mater. Sci., Vol. 39, pp. 4131-4137 (2004)) is investigated in the temperature range from 500 to 1200°C, in air, by means of differential thermal analysis (DTA), thermogravimetric analysis (TG), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), N ₂ adsorption/desorption, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The hybrid particles had an islet-like nano-structure, which consisted of titania and PDMS domains of a nanometer size. The amorphous titania domains were transformed to anatase by a heat treatment above 500°C accompanying densification, while there was no significant change in the titania domain size by the heat treatment at 900°C for 2 h. The silicone domains of the hybrid particles were transformed to amorphous silica completely by the thermal decomposition of the organic groups of the silicone at 700°C for 2 h. After a heat treatment at 1200°C for 2 h, the titania crystallites in the particle partly transformed to rutile and grew by diffusion and fusion of the titania domains accompanying a morphological change of the particles. On the other hand, the silica domains remained amorphous.