Synthesis of organic-inorganic hybrids via adsorption of dye on an amino silane-functionalised silica surface

Studies were performed on synthesis of a monodisperse active silica in an emulsion system. The obtained silica was subjected to surface modification using N-2-(aminoethyl)-3-aminopropyltrimethoxysilane in order to increase the chemical (mainly adsorptive) reactivity of the silica. On the surfaces of the raw silica material and the aminosilane-functionalised silica C.I. Reactive Blue 19 was adsorbed. The ensuing silicas and pigments were subjected to physicochemical evaluation using spectrophotometric, microscopic and laser light scattering techniques; also the specific surface area and pore characteristics were determined. Amounts of the adsorbed silane and dye were determined employing elementary analysis; the amount of silane and of dye both adsorbed and eluted from the surface of SiO2 were estimated. The silicas and pigments exhibited an almost ideal spherical particle shape and a highly uniform character of particles. This was particularly evident following adsorption of C.I. Reactive Blue 19 dye on the surface of aminosilane-modified silica. The dye was found to have chemically reacted with the aminosilane-grafted silica surface, which was proven by FTIR spectra and elementary analysis. The character was also confirmed by an alteration in value of the isoelectric point. Silicas formed in the emulsion system were found to represent a highly valuable adsorptive material, which might serve as a dye carrier. Pigments obtained in this way are chemically and physically stable. (C) 2002 Elsevier Science Ltd. All rights reserved.