Well-organized meso-macroporous TiO₂/SiO₂ film derived from amphiphilic rubbery comb copolymer

We report the facile synthesis of a well-organized meso-macroporous TiO₂/SiO₂ thin film with high porosity and good interconnectivity from a binary mixture (i.e., titania precursor and polymer template). Our process is based on self-assembly of the amphiphilic rubbery comb copolymer, poly(dimethylsiloxane)-g-poly(oxyethylene methacrylate) (PDMS-g-POEM) with titanium tetraisopropoxide (TTIP). SiO₂ is self-provided by thermal oxidation of PDMS chains during calcination under air. The selective, preferential interaction between TTIP and the hydrophilic POEM chains was responsible for the formation of well-organized TiO₂/SiO₂ films, as supported by transmission electron microscopy, scanning electron microscopy, X-ray photospectroscopy, and X-ray diffraction analyses. We investigated in detail the effect of precursor content, solvent type, and polymer concentration on thin film morphology. Photodegradation of methyl orange by the well-organized meso-macroporous TiO₂/SiO₂ film was greater than that of a dense TiO₂ film prepared without PDMS-g-POEM as well as a SiO₂-etched TiO₂ film. These results indicate that the well-organized structure and SiO₂ doping of the TiO₂ film play a pivotal role in enhancing its photocatalytic properties.