Alignment of mesoporous silica on a glass substrate by a rubbing method

Alignment of hexagonal mesoporous silica particles was achieved by a simple rubbing method used for the alignment of liquid crystals on a very thin polyimide film coated on a silica glass substrate, Mesoporous silica was synthesized through the hydrolysis of tetraethoxysilane under acidic conditions in the presence of hexadecyltrimethyl ammonium chloride. The arrangement of the elongated particles was observed with their long axes parallel to the rubbing direction. The maximum aspect ratio of the particles reached similar to 100. Both the elongation and alignment of the particles were not observed on the same substrate without the rubbing treatment. The hexagonal channel orientation was confirmed using in-plane X-ray diffraction and high-resolution scanning electron microscopy. The hexagonal mesoporous structure was retained over calcination in air and the adhesion of the particles onto the substrate was greatly improved.