Layer-by-layer assembly of polyelectrolyte/TiO2 thin films with reflection-enhancing function

Colloidal TiO2 was prepared by hydrolyzing tetra-n-butyl titanate. Composite multilayer films of poly(sodium 4-styrenesulfonate) (PSS) and colloidal TiO2 particles were layer-by-layer assembled onto optic fibers and microscope glass slides. As the PSS/TiO2 film was deposited onto the end face of a glass fiber, the reflected optic intensity periodically oscillated as the bilayer number of the film increased. After a 24-bilayer film was coated onto the both sides of a glass slide, the transmittance at 850 nm decreased more than 20%, which means that the film could serve the function as a reflection-enhancing coating. X-ray diffraction analysis and data of TEM electron diffraction analysis show that the colloidal TiO2 particles are mainly brookite nanocrystals and that the PSS/TiO2 films are polycrystalline films. Scratching experiments indicate that the composite films are of relatively high hardness.