Influence of the hydrolysis and condensation time on the preparation of hybrid materials

Abstract

This work describes the hydrolytic sol-gel synthesis of silica particles prepared by a modified Stöber route, using the organofunctionalized alkoxide 3-methacryloxypropyl trimethoxysilane and tetraethylorthosilicate. The silica particles were obtained through basic catalysis from a mixture of precursor alkoxides, water, and isopropyl alcohol. Samples were prepared with change to the pre-hydrolysis and condensation time of tetraethylortosilicate, followed by addition of the organosilane 3-methacryloxypropyl trimethoxysilane. Eu3+ ions were added to the alkoxides mixture, in order to obtain structural information about the silica particles. The samples were centrifuged, washed with ethanol, and dried at 50 ºC. The xerogel was analyzed by thermogravimetric analysis, photoluminescence, transmission electron microscopy, and infrared spectroscopy. The photoluminescence spectra revealed Eu3+ lines characteristic of the ion 5D0 7F J (J = 0, 1, 2, 3, 4) transition. The thermogravimetric curve and infrared spectra confirmed the presence of the alkoxide organic group and water in the materials. Transmission electron microscopy showed spherical particles with varied size. The time of pre-hydrolysis and condensation as well as the addition of 3-methacryloxypropyl trimethoxysilane affect the final shape and size of the materials, so they can be used as control factors.

Keywords

• sol-gel
• hybrids
• spherical silica particles
• europium III
• 3-methacrylxypropylmethoxysilane