Nonaqueous TiO2 nanoparticle synthesis: a versatile basis for the fabrication of self-supporting, transparent, and UV-absorbing composite films.

A successful strategy to obtain self-supporting (100 microm), UV-absorbing, and, in the visible region, highly transparent TiO2-poly(methyl methacrylate) (PMMA) films was developed. The 15 nm large anatase TiO2 nanocrystals were prepared in a nonaqueous sol-gel approach involving the mixing of Ti(O(i)Pr)4 and benzyl alcohol. The surfaces of the resulting particles were modified with minute amounts of organic ligands in order to make the particles easily dispersible in nonpolar media like xylene and dichloromethane and compatible with PMMA, a polymer of high optical transparency and considerable technical importance. The empirical optimization process of composite fabrication was supplemented by fundamental studies of the crystallization and growth mechanism of anatase particles in a nonaqueous medium. After the preparation of corresponding nanocomposites, the materials were investigated with respect to their UV absorption capability, optical transparency in the visible-wavelength region, and photodegradation.