Rapid pore expansion of mesoporous silica-based materials using microwave irradiation and pore swelling agents

Highlights: • Microwave irradiation in the presence of pore swelling agents increase pore diameters. • Microwave irradiation enables pore tailoring of non-calcined sol-gel mesoporous silicas. • Poly(propyleneglycol) is a safe pore swelling agent for non-calcined SBA-15 mesoporous powders. In the present work we analyze the use of microwave radiation in the presence of pore swelling agents as a post-synthesis treatment for expanding the pore size of non-calcined SiO₂-based mesoporous materials. In comparison with traditional hydrothermal treatments, using microwaves decreases significantly the time required for this process and is compatible with both ionic and non-ionic surfactant pore templates (e.g. cetyltrimethylammonium bromide (CTAB) and polypropyleneglycol-based surfactants). The evolution of the mesostructural parameters has been followed with small angle X-ray scattering (SAXS), X-ray diffraction (XRD), field-emission Scanning electron microscopy (FESEM) and N₂ porosimetry. In particular, this strategy allows an easy approach for post-processing non-calcined templated siliceous materials and tailoring their final pore dimensions.