Effects of HPC on the microstructure and hydrophilicity of sol–gel-derived TiO 2 films

Abstract

Sol–gel-derived titanium dioxide (TiO 2) coating films were prepared with various amount of hydroxypropylcellulose (HPC) as additive. The formation mechanism of HPC-modified TiO 2 films was studied by FTIR analysis of the sols. It was revealed that HPC anchors on the surface of TiO 2 colloid. The action between the polymers decides the distribution of TiO 2 colloid in the sol. Transmission electrical microscopy (TEM) and scanning electrical microscopy (SEM) showed that the particle size of TiO 2 decreased and the microstructure of the film became loose with the addition of HPC, reaching an optimum when the concentration of HPC was 4.5×10 −3 g/g sol. Further addition of HPC made the microstructure became dense. The photo-induced hydropholicity and the photocatalytic activity of the films were evaluated. The film showed good self-cleaning ability when the concentration of HPC was 4.5×10 −3 g/g sol, which can be ascribed to its uniform less agglomerated microstructure.