Different neutral surfactant template extraction routes for synthetic hexagonal mesoporous silicas

摘要

The co-condensation of a tetraethoxysilane molecule on a neutral n-octylamine surfactant template is a convenient synthetic methodology for mesostructured material preparations. Distinct routes of template removal were investigated. The neutral surfatant was removed by calcination, hot solvent extraction, heating at 150 deg C, in vacuo at room temperature and at 100 degf C, and air drying, with the products assigned as HMM, HMS, HME, HMV1, HMV2 and HM, respectively. ~29Si NMR, infrared, surface area, pore diameters and pore volume determinations were employed to characterize each sample. Elemental analysis detected the presence of amine residues of 1.8, 1.2, 0.2, 1.6 and 0.30 mmol g~(-1) for HMA, HME, HMS, HMV1 and HMV2, respectively. The HMM, HMS and HMV2 samples presented a low amount of residues, and HMS and HMV2 have the great advantage of permitting template removal without calcination.