6533b85dfe1ef96bd12bdd72

RESEARCH PRODUCT

Pore shape affects the determination of the pore size of ordered mesoporous silicas by mercury intrusion.

subject

description

MCM-41 and SBA-15 micelle-templated silicas are ideal reference materials to study the effect of surface roughness on pore size measurement by mercury intrusion, as the inner surface of the mesoporous channels is much rougher in the case of SBA-15 than MCM-41. In the case of MCM-41, the pressure of mercury intrusion is related to the pore size by the classical Washburn−Laplace law, while in the case of SBA-15, the pressure of intrusion is much higher than expected and classical models underevaluate the size of the channels. Defects on the pore surface of SBA-15 affect the mercury intrusion in a similar way as the deviation from cylindrical geometry does for the pores of spongelike silica glasses. The results vindicate the models of Wenzel and Kloubek on the effect of surface defects on the mercury contact angle, which is significantly larger for a rough surface than for a plane surface. The surface defects of SBA-15 does not affect the evaluation of the mesopore size by nitrogen adsorption, as they are fi...