Molecular self-assembly of TiO2/polymer nanocomposite films

Multilayer ultrathin films composed of titanium dioxide nanosized particles and ionic polystyrene molecules have been fabricated on single-crystal silicon, quartz, and glass substrates by a novel molecular self-assembly process. X-ray photoelectron Spectroscopy (XPS) indicates that the formed cationic TiO2 particles adsorb only on negatively charged and not on positively charged surfaces. Contact angle measurements demonstrate that the water contact angle oscillates regularly in accordance with which molecules form the outermost layer of the films. A molecular-level ordered transparent film, up to 120 layers (60 bilayers) in thickness, has been obtained and characterized by UV-vis spectroscopy. It is also demonstrated that film transmission in the UV light range decreases progressively with an increasing number of the bilayers and negligible attenuation in the visible range.