Analytical Sciences

Adsorption and Desorption Dynamics of Sodium Dodecyl Sulfate at the Octadecylsilane Layer on the Pore Surface of a Mesoporous Silica Film Observed in-situ by Optical Waveguide Spectroscopy

Akira YAMAGUCHI,*1,*2 Hiroyuki ARAFUNE,*3 Kazuhiro HOTTA,*3 Tetsuji ITOH,*4 and Norio TERAMAE*3

*1 College of Science, Ibaraki University, 2-1-1 Bunkyo, Mito, Ibaraki 310-8512, Japan
*2 Frontier Research Center for Applied Atomic Sciences, Ibaraki University, Tokai, Ibaraki 319-1106, Japan
*3 Department of Chemistry, Graduate School of Science, Tohoku University, Aoba, Sendai 980-8578, Japan
*4 Research Center for Compact Chemical System, National Institute of Advanced Industrial Science and Technology (AIST), 4-2-1 Nigatake, Miyagino, Sendai 983-8551, Japan

The purpose of this study is to apply optical waveguide (OWG) spectroscopy to observe adsorption and desorption dynamics occurring in a surfactant-templated mesoporous silica film. For that purpose, a mesoporous silica (MS) film with open accessible pores (pore diameter, ca. 6 nm) was formed on an aluminum (Al) layer deposited on a glass substrate, and the pore surface of the MS film was modified with octadecylsilane (ODS). The resulting ODS-modified MS (ODS-MS) and Al multilayer film showed a clear waveguide coupling dip in the reflection spectrum. The position of the waveguide coupling dip was red-shifted as the amount of sodium dodecyl sulfate within the ODS-MS layer increases. These results indicate the usefulness of OWG spectroscopy for the study of adsorption/desorption dynamics occurring in MS materials.

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