Shear and salt effects on the structure of MCM-41 synthesis gels

Abstract

Orientational ordering under shear was observed for some precursor gels for the synthesis of the hexagonal mesoporous silica MCM-41 in the presence of high KBr concentrations. The presence of KBr disrupted the formation of the first-order MCM-41 diffraction peak dependent upon KBr concentration. Synthesis gels which formed good quality MCM-41, but with no added KBr salt, were not oriented by strong shearing. In addition MCM-41 formed without shear and salt was not disrupted by subsequent shearing.