Synthesis of onion-like mesoporous silica from sodium silicate in the presence of α,ω-diamine surfactant

Mesoporous silicas with vesicular and onion-like morphologies were assembled through hydrogen-bonding pathway from sodium silicate as silica source and electrically neutral alpha,omega-diamine, Jeffamine D2000 surfactant (H2NCH(CH3)CH2[OCH2CH(CH3)](33)NH2) as template in aqueous media at different synthesis temperatures (25, 60 and 100 degrees C). Assembling the material at 100 degrees C afforded onion-like core shell mesoporous silica, while at relatively lower temperature, e.g. 25 and 60 degrees C, multilamellar vesicles were obtained. Mesoporous silica with onion-like morphology was also obtained by a two-step synthesis involving an aging period of 20 h at room temperature followed by a hydrothermal stage (1-12 h) at 100 degrees C. The heavily cross-linked (Q(4)/Q(3) ratio of 4.43) onion-like mesophase silica exhibited high hydrothermal stability. The BET surface area, pore volume and KJS (Kruk-Jaroniec-Sayari) pore diameter of the onion-like mesoporous silica were found to be 464 m(2) g(-1), 1.16 m(3) g(-1) and 7.2 nm, respectively. (C) 2008 Elsevier Inc. All rights reserved.