Photopatternable nanoporous titania films by coassembly of diblock copolymer and chemically modified titanium alkoxide

Abstract

Nanostructured titania has received increasing attention due to their attractive optical and electrical characteristics. Various diblock copolymers or triblock copolymers have been used as structure-directing agents for nanostructured titania. However, highly acidic conditions are required to reduce the condensation rate during self-assembly and careful environment control to obtained desired nanostructures due to the increased reactivity and high sensitivity to moisture of typical titania precursors. The chelated oligomeric titanate provides not only excellent stability during self-assembly, but also the photosensitivity for photo-patterning. In the present work, we demonstrate a method to create photo-patternable nanoporous titania thin films using coassembly of polystyrene and poly(ethylene oxide) diblock copolymers and a chemically modified oligomeric titanate. With this approach, nanoporous titania film was successfully obtained with nano-crystalline anatase phase. Micron-sized patterning of nanohybrid film was performed as well. The patterned nanoporous titania films could potentially be used for applications including photovoltaic cells, optics, and photocatalysts.