ABSTRACT
I. INTRODUCTION For several decades now, organic molecules have been used to direct the structure of porous inorganic solids. For example, Barrer and Kerr (Mobil) pioneered the use of organic cations, such as tetramethylammonium ions as ingredients for zeolite synthesis [1,2]. The application of such structure directors has been extended to a large number of zeolite syntheses [3] leading to over a hundred zeolite structures [4]. The pore openings in these crystalline materials have spanned the range from about 3 to 13 A˚ . Because zeolites have shown tremendous commercial success in applications including ion exchange, size-and shape-selective catalysis, and separation [5], much research effort has focused on tailoring material compositions and pore sizes to optimize materials properties and to accommodate larger guest molecules. In the search for larger pore materials, a breakthrough was made in the early 1990s when Mobil announced the synthesis of a new family of mesoporous molecular sieves (M41S) that were prepared in surfactant solutions [6-9]. The new class of silicates and aluminosilicates possess ordered arrays of uniform channels that are tens of angstroms in diameter. In the surfactant-templated syntheses, aggregates of surfactant molecules rather than individual molecules fill the space that eventually forms the channels in the porous solids. Since the original publications, hundreds of scientific papers as well as several review articles have appeared describing research on ordered mesoporous sieves and related mesostructured materials. The compositional range for mesoporous materials has
been greatly expanded, and new structures and morphologies have been developed by tuning the synthesis procedures. This chapter focuses on the role that surfactants and other amphiphiles play in controlling and modifying the structure of porous inorganic solids.
