Remarkable Birefringence in a TiO2–SiO2 Composite Film with an Aligned Mesoporous Structure
- 4 August 2011
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 133 (34), 13539-13544
- https://doi.org/10.1021/ja204384m
Abstract
Mesoporous titania–silica composite films with highly aligned cylindrical pores are prepared by the sol–gel method using a substrate with structural anisotropy. The strong alignment effect of a rubbing-treated polyimide film on a substrate provides a narrow alignment distribution in the plane of the film regardless of the fast condensation rate of titania precursors. The collapse of the mesostructure upon the surfactant removal is effectively suppressed by the reinforcement of the pore walls with silica by exposing the as-deposited film to a vapor of a silicon alkoxide. The existence of a silica layer on the titania pore wall is proved from the distributions of Ti and Si estimated by the elemental analysis in high resolution electron microscopy. The obtained mesoporous titania–silica composite film exhibits a remarkable birefringence reflecting the highly anisotropic mesoporous structure and the high refractive index of titania that forms the pore wall. The Δn value estimated from the optical retardation and the film thickness is larger than 0.06, which cannot be achieved with the conventional mesoporous silica films with uniaxially aligned mesoporous structure even though the alignment of the pores in the films is perfect. These inorganic films with mesoscopic structural anisotropy will find many applications in the field of optics as phase plates with high thermal/chemical/mechanical stabilities.Keywords
This publication has 48 references indexed in Scilit:
- Vertically oriented hexagonal mesoporous films formed through nanometre-scale epitaxyNature Materials, 2008
- Design, Synthesis, and Properties of Inorganic and Hybrid Thin Films Having Periodically Organized NanoporosityChemistry of Materials, 2008
- Photo-Alignment Behavior of Mesoporous Silica Thin Films Synthesized on a Photo-Cross-Linkable Polymer FilmChemistry of Materials, 2006
- Photo-orientation of mesoporous silica materials via transfer from an azobenzene-containing polymer monolayerElectronic supplementary information (ESI) available: details on the experimental procedures and IR spectra around the siloxane stretching band. See http://www.rsc.org/suppdata/jm/b3/b310296c/Journal of Materials Chemistry, 2004
- Photovoltaic cells made from conjugated polymers infiltrated into mesoporous titaniaApplied Physics Letters, 2003
- Photo-orientation of Mesostructured Silica via Hierarchical Multiple TransferChemistry of Materials, 2002
- Preparation of Mesoporous Silica Films with Fully Aligned Large Mesochannels Using Nonionic SurfactantsChemistry of Materials, 2002
- Highly Organized Mesoporous Titania Thin Films Showing Mono-Oriented 2D Hexagonal ChannelsAdvanced Materials, 2001
- Highly Oriented Mesostructured Thin Films: Shear-Induced Deposition of Optically Anisotropic Coatings of Tungsten Oxide/Surfactant CompositesLangmuir, 1999
- Preparation of Supported Mesoporous Silica Layers in a Continuous Flow CellChemistry of Materials, 1997