Morphology-selective synthesis of mesoporous SBA-15 particles over micrometer, submicrometer and nanometer scales

Mesoporous silica structures are of increasing importance as supports for enzymes and molecular organometallic catalysts. For high-surface-area, porous 3-d catalytic supports, the relationship between the exterior particle morphology and the 3-d mesopore structure is of particular significance. This paper describes the designed synthesis of selected morphologies of mesoporous SBA-15, which can be chosen from micrometer sized spheres to hundreds or tens of nanometers sized monodispersed particles such as platelets, hexagonal columns, rice-shapes, rods with tunable aspect ratios, and donuts. These are directly synthesized via control of the fundamental synthesis factors, including initial temperature, stirring rate and micelle packing parameter, rather than by the use of additives that have been generally utilized for specific morphologies in previous reports. The relationship between these basic synthesis parameters and morphologies provides insights into the formation of mesostructured materials. The SBA materials with various morphologies are expected to be useful in applications that require anisotropic or path-length-controlled diffusion.