Block copolymer–cyclodextrin supramolecular assemblies as soft templates for the synthesis of titania materials with controlled crystallinity, porosity and photocatalytic activity†
Abstract
Nanostructured titania materials with tunable porosity and crystalline framework were prepared in an aqueous phase by using a template-directed colloidal self-assembly strategy. The approach employs the supramolecular assemblies formed between the randomly methylated β-cyclodextrin and the block copolymer P123 as soft templates and the sol–gel synthesised TiO2 nanocrystals as building blocks. By combining X-ray diffraction, N2-adsorption, field emission scanning electron microscopy and UV-visible spectroscopy, we show that considerable control over crystallite size, polymorph content and particle morphology could be achieved by using a delicate balance between the composition and structure of the supramolecular template as well as the reaction conditions. The photocatalytic activity of these mesoporous TiO2 materials was evaluated in the photodegradation of a toxic herbicide, the phenoxyacetic acid (PAA), and was correlated to the structural and textural characteristics of the photocatalyst.