Abstract
Trimethylsiloxysilicate (TMS) is used in various types of cosmetics because it forms a protective film that is highly water repellent, lubricating, and lasting. The authors tried to develop silicone polymers that contain titanium dioxide (trimethylsiloxysilicate containing titanium dioxide: TMST) to improve the optical properties of TMS. We prepared TMST by exploiting the sol-gel reaction to co-hydrolyze and polymerize silicone alkoxide and titanium (IV) alkoxide, while trimethylsilylating the intermediates. The TiO2 units in TMST were strongly bound to and homogeneously incorporated in the ≡Si-O-Si≡ network structure, rather than the simple dispersion of particles of a fine titanium dioxide in TMS. The component units of TMST are [(CH3)3SiO1/2]:[SiO2]:[TiO2] (mol ratio 1.4:1.2:0.4). TMST is capable of forming film, which, although containing 9.0% titanium dioxide by weight, has good transparency because the titanium dioxide is highly dispersed and anchored. TMST retains the solubility of TMS, which has been a popular material for cosmetics, as well as the functional (transfer resistant and water repellent) film forming capabilities of TMS. In addition, TMST has the unique optical characteristics (higher refractive index and ultraviolet screening function) attributable to the titanium dioxide contained. These results demonstrated that TMST is very useful as a new functional film forming agent in cosmetics.
