Remarkable birefringence in a TiO2-SiO2 composite film with an aligned mesoporous structure

Hirokatsu Miyata, Yuta Fukushima, Kohei Okamoto, Masahiko Takahashi, Masatoshi Watanabe, Wataru Kubo, Atsushi Komoto, Shin Kitamura, Yosuke Kanno, Kazuyuki Kuroda

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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.

Original languageEnglish
Pages (from-to)13539-13544
Number of pages6
JournalJournal of the American Chemical Society
Volume133
Issue number34
DOIs
Publication statusPublished - 2011 Aug 31

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ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Miyata, H., Fukushima, Y., Okamoto, K., Takahashi, M., Watanabe, M., Kubo, W., Komoto, A., Kitamura, S., Kanno, Y., & Kuroda, K. (2011). Remarkable birefringence in a TiO2-SiO2 composite film with an aligned mesoporous structure. Journal of the American Chemical Society, 133(34), 13539-13544. https://doi.org/10.1021/ja204384m