Tailoring the properties of sub-3 μm silica core-shell particles prepared by a multilayer-by-multilayer process

Sub-3 μm silica core-shell particles (CSPs) were fabricated by a multilayer-by-multilayer method recently developed in our group. In this work, we report on methods to prepare and modify the properties of these CSPs by high temperature calcination, pore size enlargement under basic conditions, and rehydrolyzation in boiling water to make them more suitable as starting materials for preparation of HPLC columns. The chemical, physical and mechanical properties of these modified CSPs were characterized by scanning electron microscopy (SEM), infrared spectroscopy (IR), thermogravimetric analysis (TGA), and nitrogen sorption porosimetry. CSPs obtained after these treatments were observed to have the following properties: particle diameter ∼2.7 μm, shell thickness ∼0.5 μm, surface area ∼200 m(2)/g, pore diameter ∼10 nm (and almost no mesopores), pore volume ∼0.5 cc/g, and Si-OH group surface concentration ∼4 OH/nm(2). These properties are in line with those of commercially available sub-3 μm CSP products.