Facile synthesis of silica-manganese oxide nanocomposites with core-shell structure using surfactant and cosurfactant

Abstract

In this study, silica-manganese oxide (Mn(3)O(4)) nanocomposites with core-shell structure were synthesized using surfactant and cosurfactant in the sol-gel reaction medium for the formation of spherical silica nanoparticles at basic condition using NH(4)OH as a catalyst. In order to prepare the composites of silica and Mn(3)O(4), the aqueous solution of manganese nitrate, cetyltrimethylammonium bromide (CTAB) and tert-butanol (t-butanol) was added into the sol-gel reaction solution after the formation of silica particles which would be negative-charged at basic condition. CTAB and t-butanol as binders induced the attractive interaction between silica and Mn(OH)(2) by their adsorption onto the surface of Mn(OH)(2) formed by the reaction between Mn nitrate and NH(4)OH. After the Mn(OH)(2) particles were prepared, they were transformed into Mn(3)O(4) through the oxidation in air due to its very high reactivity. Through this process, the silica-Mn(3)O(4) nanocomposites with controllable core-shell structure were synthesized with the variations of volume of Mn solution and concentrations of Mn nitrate, CTAB, and t-butanol. The characterizations of the silica-Mn(3)O(4) nanocomposites were performed using FE-SEM, TEM, EDS, XRD, and TGA. The magnetization of composites was studied using a vibrating sample magnetometer (VSM) at room temperature in the range of -5000 to 5000 Oe.