Physicochemical and morphological properties of hydrated silicas precipitated following alkoxysilane surface modification (original) (raw)

Modi®ed silicas were obtained by precipitation from aqueous solutions of sodium metasilicate and sulphuric acid. For the modi®cation, silane coupling agents with various functional groups were applied, including aminosilane (AEAPTS), glycidoxysilane (GPTS), mercaptosilane (McPTS), and vinylsilane (VTMES). Extensive physicochemical evaluation of the obtained modi®ed silicas was conducted, using FTIR, 29 Si CP MAS NMR and XPS techniques. The silica surface modi®cation was proven to depend upon chemical reactions and to show intensity increasing with a rising concentration of a given modi®er. A surface charge of the formed silica dispersions was also examined, by determining their zeta potential. Moreover, surface morphology, dispersion and particle size of the obtained silicas were evaluated, employing TEM electron microscopy and the technique of a dynamic light scattering (DLS). The studies demonstrated that application of hydrophobic type silanes for surface modi®cation of the hydrated silicas restricted the intense tendency for agglomeration in the formed precipitated silicas. #