Evaluation Methods of Silica Surface—Focusing around Hydroxyl Groups

Abstract

Silica materials have been practically used in various fields. In this paper the evaluation methods of silica surface are discussed, especially focusing the surface hydroxyl groups which play the important roles of surface and interface phenomena. Previously reported estimation methods were summarized. New information about the two-dimensional distribution of surface hydroxyls and the structure of hydrogen-bonded hydroxyls using the probe molecules was reported. The surface properties of crystal silicas were investigated. Lastly the origin of hydroxylation by the cleavage of surface siloxane bonds with water adsorption was discussed from the standpoint of the rings of SiO₄ tetrahedra unit.