Shell Thickness Control of Mesoporous Silica Hollow Capsules and Their Release Behavior

Y. Yamaguchi, N. Kato
Meiji university, JP

Keywords: mesoporous silica hollow capsule, shell thickness


we propose the method to control the shell thickness of the mesoporous silica hollow capsules (MSHCs) and the method to load the materilas into the MSHCs. The release behavior was also invesitgated. The template-assisted method was used. Polystyrene particles (80nm in diameter) were used as the template for the hollow part, and the templates for the mesopores across the shell was cylindrical micelles. The silica/micelle complex was formed on the polystyrene particle by the sol-gel method. The coated particles were then calcined to decompose the templates, resulting in the MSHCs. To make the shell thicker, the sol-gel reaction was repeated. As the number of the repetition increases, the thickness increases, indicating that the proposed method provides a precise control of the shell thickness. The alizarin dye was loaded to the capsules. The MSHCs were dispersed in the acetone solution of alizarin. The acetone was dried to precipitate the alizarin, followed by redispersion in the saturated aqueous solution of alizarin. After removal of the alizarin precipitated outside the capsules, the alizarin-loaded MSHCs were obtained. The TEM image shows that the hollow part of the capsule was filled with alizarin. The release behavior was also observed by TEM.