ABSTRACT
II. Curvature and Confinement 123 A. A pinch of stereology and mathematical morphology 123 B. Curvature and connectivity in silicas 128 c. From two-dimensional to three-dimensional 134 D . Adsorption , disorder, and confinement 139 E. Adsorption , disorder, and curvature 141
Ill. Roughness , Scale Invariance, and Hierarchy 143 A. Scale invariance: self-similarity and self-affinity 146 B. The nanoscale texture of silicas and their surface roughness 150 c. Experimental methods and evidence 154
I. INTRODUCTION
This chapter is devoted to a simple question: How does the shape of the surface of silica influence its adsorption properties? A priori, this is a general question which is not limited to silicas. Any porous medium may be described as an interface exploring the embedding three-dimensional space and partitioning it into two subspaces: matter and void. The morphological complexity of that interface, from subnanometric to macroscopic scale, is virtually unlimited . It is the result of all the elemen-
tary processes involved in the material synthesis. Considering the variety of processes involved in amorphous silica synthesis (polymerization, growth, aggregation, sintering, and drying, to quote a few), some of them occurring in thermodynamic equilibrium conditions and some in out-of-equilibrium conditions, it is no wonder that Silicaland offers a particularly rich variety of landscapes, being rivaled in that only by porous carbons.
