Template Removal and Thermal Stability of Organically Functionalized Mesoporous Silica Nanoparticles

Abstract

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 °C. The surfaces were functionalized with 2,2‘-bipyridine, 4-(dimethylamino)pyridine, and pentafluorobenzene. The 13C and 29Si 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.

Pore ordering in mesoporous matrices induced by different directing agents

“…2), due to desorption of the physisorbed and chemisorbed water [31][32][33]. CTAB starts to decompose above 200 °C [34]. The surfactant transformations with temperature during calcination are well recognized up to ~250 °C.…”

Review: Bioanalytical applications of biomolecule-functionalized nanometer-sized doped silica particles

“…An unwanted consequence, for example, of functionalization with amine-containing silanes is that the colloidal stability may decrease, and particles may aggregate in water (caused by a reduction in the overall charge of the particle at neutral pH). This problem could be resolved using the addition of inert negatively charged silanes, which contain phosphonate (e.g., (3-trihydroxy)silylpropyl methylphosphonate, THPMP) or other groups [125,126]; alternatively, PEGylated silanes may be added, which are highly hydrophilic [127][128][129]. A novel precision-assembly methodology based on the controlled, simultaneous assembly of a core nanoparticle substrate in a polyelectrolyte solution (polyethyleneimine) was recently described by Bringley et al [130].…”

Urea and Thiourea-Functionalized Mesoporous Silica Nanoparticle Catalysts with Enhanced Catalytic Activity for Diels–Alder Reaction

“…Toward this goal, several design prerequisites, such as tuning the degree of surface functionalization [5][6][7], controlling the spatial distribution of functional groups [8,9], and improving the hydrothermal stability of the catalytic materials [10][11][12][13][14], have been recently demonstrated.…”