Surfactant-Free Synthesis of Macroporous TiO2 Films by a Photopolymerization-Induced Phase-Separation Method

摘要

TiO2 films with controlled macroporous structures have been prepared from the precursor solution containing photomonomer dipentaerythritol pentaacrylate by a photopolymerization-induced phase-separation method (PIPS) in the absence of any surfactant and colloidal templates. The gel TiO2 film deposited from the precursor solution by dip-coating was irradiated with the ultraviolet light for some time. During the irradiation process, the polymerization of the photomonomer was induced, which resulted in the phase-separation in the film system. At the end of the polymerization reaction, two phases existed in the film, one was the emerging polymer rich phase, and another was the residual monomer-TiO2 oligomer-rich phase. After heat-treatment at 600 °C, the entire polymer decomposed and a well-defined interconnected macroporous TiO2 films could be obtained. X-ray diffraction, scanning electron microscopy, atomic force microscopy, thermogravimetric, and differential thermal analysis were used to characterize the macroporous TiO2 films. The results showed that the macroporous texture could be tuned by changing the composition of the precursor solution and the type of the reactive monomer. Polyvinylpyrrolidone was introduced into the system to slow the solvent evaporation. Highly macroporous TiO2 films prepared by the PIPS method exhibited much higher photocatalytic activity for the decomposition of methylene blue dye than the dense TiO2 film.