MORPHOGENESIS OF SHAPES AND SURFACE PATTERNS IN MESOPOROUS SILICA

The synthesis of inorganic materials with complex form, using surfacta nt assemblies as supramolecular templates(1-13), has ramifications in areas as diverse as large-molecule catalysis, the formation of semicon ductor nanostructures, biomolecule separations, the development of med ical implants and the morphogenesis of skeletal forms(14). Here we des cribe a procedure for the synthesis of hexagonal mesoporous silica tha t produces a remarkable array of shapes, surface patterns and channel plans. Our reaction conditions favour curved morphologies including to roidal, disk-like, spiral and spheroidal shapes. We use scanning elect ron microscopy to catalogue the basic topologies and surface patterns, and transmission electron microscopy to establish the relationship be tween morphology and the underlying mesostructure. Polarized optical m icroscopy enables us to identify a connection between optical anisotro py in these structures and the periodic porous mesostructure. We propo se that the morphogenesis of these shapes and surface patterns can be rationalized in terms of the growth of a silicate liquid-crystal embry o(15,16) with a hexagonal cross-section that, under different initial reaction conditions, is subject to increasing degrees of curvature.