Formation and photopatterning of nanoporous titania thin films

Abstract

Photopatternable nanoporous titania thin films were generated from mixtures of an organic diblock copolymer, poly(styrene- b -ethylene oxide) (PS-b-PEO), and an oligomeric titanate (OT) prepared from a chelated titanium isopropoxide. The PS-b-PEO templates well-defined microdomains in thin films of the mixtures, which upon thermal treatment at 450 °C, become nanopores in titania. Average pore size and porosity are controlled by the molecular weight and loading level of the PS-b-PEO, respectively. Patterns of nanoporous titania were created by selectively exposing UV light on the mixture films. The UV irradiation destroys the chelating bond and induces the cross-linking reaction of the OT. Subsequent wet development followed by thermal treatment gives patterned nanoporous films of anatase phase titania. © 2007 American Institute of Physics.