Synthesis of mesoporous silica and carbon using triblock copolymer surfactant

Abstract

A series of mesoporous silica was synthesized by using mixtures of PEO-PO-EO-type triblock copolymers, P123 $(EO_20PO_70EO_20)$ and F127 $(EO_106PO_70EO_106)$, as surfactants under acidic condition. In this research, it has been found out that pore sizes of the mesoporous materials can be controlled by the composition of the amphiphilic nonionic surfactants and the hydrothermal treatments during synthesis. The mesoscopically ordered silica underwent a structural transformation from cage-type cubic Im3m mesoporous silica structure to 2-dimensional hexagonal p6mm through a mixed phase containing of cubic Fm3m and 3-D hexagonal $P6_3$ /mmc, as the average number of EO group (n) in the block copolymer mixtures $(EO_nPO_70EO_n)$ was decreased. Compared with these structured changes, the hydrothermal treatment time caused a significant effect on the structural parameters: the pore diameter, pore volume, and BET surface area. The resultant cage-type mesoporous silica materials with increased pore diameters were found out to be suitable as templates for synthesis of a new mesoporous carbon, CMK-7.