The effect of film thickness and TiO 2 content on film formation from PS/TiO 2 nanocomposites prepared by dip-coating method

Abstract

Steady-state fluorescence (SSF) technique in conjunction with UV-visible (UVV) technique and atomic force microscope (AFM) was used for studying film formation from TiO 2 covered nanosized polystyrene (PS) latex particles (320nm). The effects of film thickness and TiO 2 content on the film formation and structure properties of PS/TiO 2 composites were studied. For this purpose, two different sets of PS films with thicknesses of 5 and 20μm were prepared from pyrene-(P-) labeled PS particles and covered with various layers of TiO 2 using dip-coating method. These films were then annealed at elevated temperatures above glass transition temperature (T g) of PS in the range of 100-280°C. Fluorescence emission intensity, I p from P and transmitted light intensity, I tr were measured after each annealing step to monitor the stages of film formation. The results showed that film formation from PS latexes occurs on the top surface of PS/TiO 2 composites and thus developed independent of TiO 2 content for both film sets. But the surface morphology of the films was found to vary with both TiO 2 content and film thickness. After removal of PS, thin films provide a quite ordered porous structure while thick films showed nonporous structure. © 2012 M. Selin Sunay et al.