Stepwise functionalization of mesoporous crystalline silica materials

Abstract

Novel properties have been achieved in mesoporous crystalline silica materials by organic functionalization. In this study, localized functionalization and bifunctionalization of silica MCM-41 was attempted through the stepwise post-synthesis silylation. When MCM-41 was treated with various silylating agents for 6 hours before template removal, change in pore size only was observed without any change in surface area and pore volume. MCM-41 was difunctionalized with both decyl groups on edges of pores and methyl groups on inner surfaces of pores. Capillary condensation of water took place at higher relative pressure in MCM-41 with decyl groups on edges than in unsilylated MCM-41, whereas hydrophobic property was observed in MCM-41 which were difunctionalized with decyl groups on edges of pores and with methyl groups on inner surfaces of pores. This study shows that the manipulation of pore size and functionality with/without any change in surface area and pore volume and the combination of two different functionalities could be achieved in MCM-41 through the stepwise functionalization.