Template removal and thermal stability of organically functionalized mesoporous silica nanoparticles

The surfaces of organically functionalized, MCM-41-type mesoporous silica nanoparticle materials, prepared by a co-condensation method, were studied by solid-state nuclear magnetic resonance (NMR) spectroscopy following a series of heat treatments between 100 and 400 degrees C. The surfaces were functionalized with 2,2'-bipyridine, 4-(dimethylamino)pyridine, and pentafluorobenzene. The C-13 and Si-29 NMR spectra of these materials showed that the structures and concentrations of these functional groups remained unaffected by the heat treatment. Furthermore, it has been demonstrated that the surfactant template, cetyltrimethylammonium bromide ( CTAB), could be effectively removed from these materials by heat treatment without disrupting the covalent bonds between the functional groups and the silica surface. The chemical accessibility and reactivity of the organic functionalities were also preserved after heating.