INFLUENCE OF N-2-(AMINOETHYL)-3- AMINOPROPYLTRIMETHOXYSILANE ON PHYSICOCHEMICAL AND MORPHOLOGICAL PROPERTIES OF SILICAS OBTAINED

Synthesis of monodisperse silica was performed in a precipitation reaction from aqueous solution of sodium metasilicate using hydrochloric acid in an emulsion system. Effect of N-2-(aminoethyl)-3-aminopropylotrimethoxysilane was studied on surface and morphological properties of the precipitated silica. Particle size and polydispersity were measured using the technique of dynamic light scatter (DLS) and scanning electron microscopy (SEM). The extent of surface modification and its type were evaluated using FTIR spectroscopy. Moreover, adsorptive properties were characterised by estimation of specific surface area (BET) and of macroporosity. The XPS technique permitted to quantify the amount of modifier deposited on silica surface. Alterations in surface charge were studies by estimation of isoelectric point by direct testing of electrophoretic mobility and, indirectly, by calculating zeta potential. Aminosilane modification of SiO2, formed in emulsion medium, results in extensive changes in surface character and in morphology of the particles. Already at the time of silica preparation surface silanol groups become markedly reduced and, in addition, aminosilane chemisorption results in augmented hydrophobicity. Increased particle homogeneity has also been obtained and a decreased value of polydispersity due to aminosilane interactions with the surface of examined silica