Synthesis of KIT-6 type mesoporous silicas with tunable pore sizes, wall thickness and particle sizes via the partitioned cooperative self-assembly process

Abstract

With bi-continuous cubic mesostructures of Ia3d symmetry and interpenetrating cylindrical pore system, KIT-6 type mesoporous silica has attracted a great deal of interest for its application in various areas. Unfortunately, so far the reports on the tuning of mesostructures or other physical properties are rather limited due to the restrictions on synthetic conditions. In this work, one previously reported partitioned cooperative self-assembly (PCSA) process was applied for the synthesis of KIT-6s with good meso-orderings, allowing facile manipulation over mesostructures, e.g. the mesopore size, pore wall thickness and particle sizes. By simply partitioning the addition of tetraethoxysilane (TEOS), the mesopore sizes of KIT-6s can be varied between around 8 and 10nm (KJS). For a given addition combination (1st part of 7.0g and 2nd part of 3.0g in total 10.0g TEOS), the meso-orderings show some improvement with the increase in the interval time from 1 to 5h. In combination with hydrothermal treatment at high temperatures (e.g. 140°C), the PCSA process, though not yielding larger mesopore sizes, favors the formation of KIT-6 with higher meso-orderings than that of conventional method derived KIT-6. Moreover, the particle sizes of KIT-6s can be significantly reduced from sub-millimeter to several microns via the PCSA process. The PCSA process thus represents a simple but effective way to manipulate the mesostructures and particle sizes of KIT-6s.