Facile synthesis of tailored nanostructured ORMOSIL particles by a selective dissolution process

Abstract

Tailored nanostructured ORMOSIL particles, of raspberry shaped, hollow, and rattle type structures, were prepared by a selective dissolution of siloxane networks in composite ORMOSIL particles with a multilayered structure. The synthesis of monodisperse ORMOSIL particles involved a one-pot process in an aqueous solution using a binary or ternary mixture from three organosilanes, (3-aminopropyl)trimethoxysilane (APTMS), vinyltrimethoxysilane (VTMS), and/or phenyltrimethoxysilane (PTMS). In the following step, ORMOSIL particles were treated with a mixture of water and alcohol with mild heating. This mild etching process was efficient to selectively dissolve some of organosilane functional groups within the ORMOSIL particles but not their main silica frameworks, leading to formation of mesoporous particles. The strategy developed in this study is not only very facile, economical, and less time-consuming, but also more environmentally friendly by avoiding the use of corrosive etching chemicals and harsh reaction conditions. Surface roughness, core diameter, and shell thickness of the resultant mesoporous ORMOSIL particles were controlled by manipulating synthetic parameters such as the relative ratios of the silane monomers as well as the dissolution parameters such as temperature and type of solvent.