(42s) Effect of Synthesis and Template Removal Condition on the Quality of Mesoporous Silica Membrane

Authors: 
Hosoya, A., Soka university
Ida, J., Soka University
Ochi, M., Soka University
Matsuyama, T., Soka University
Yamamoto, H., Soka University

To establish how to prepare high quality mesoporous silica membrane, the effect of synthesis condition and template removal condition on the membrane quality was examined.  Ordered mesoporous silica membrane was prepared by spin-coating on porous alumina disc using tetraethoxysilane (TEOS) as a silica source and cetyltrimethylammonium bromide (CTAB) as a template surfactant.  Since the substrate had relatively large pores, the pores were filled with paraffin to prevent a mesoporous silica preparation solution from immersing. After forming mesoporous silica membrane on the alumina substrate, the paraffin was removed by toluene. It is also known that mesoporous silica membrane experiences the shrinkage of silica framework, which causes defect, during removing process of template surfactant in the case of using calcinations for removal.  To reduce the shrinkage, template removal by solvent extraction method was tried instead of calcination.  Shrinkage of silica framework was greatly reduced by solvent extraction method using formic acid solution, but the extracted membrane showed structure collapse to some extent after removing surfactant.  Therefore, pre-treatment of as-synthesized mesoporous silica membrane by tetramethoxysilane (TMOS) vapor was performed to increase silica density before template removal.  As a result, the TMOS-treated membrane using solvent extraction showed lowest shrinkage ratio and maintained mesoporous silica structure even after surfactant removal.