Acta Phys. -Chim. Sin. ›› 2013, Vol. 29 ›› Issue (03): 646-652.doi: 10.3866/PKU.WHXB201212252

• PHYSICAL CHEMISTRY OF MATERIALS • Previous Articles     Next Articles

Macroporous SiO2 Monoliths Prepared via Sol-Gel Process Accompanied by Phase Separation

GUO Xing-Zhong1, LI Wen-Yan1, ZHU Yang2, NAKANISHI Kazuki2, KANAMORI Kazuyoshi2, YANG Hui1   

  1. 1 Department of Materials Science and Engineering of Zhejiang University, Hangzhou 310027, P. R. China;
    2 Department of Chemistry, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
  • Received:2012-09-15 Revised:2012-12-24 Published:2013-02-25
  • Supported by:

    The project was supported by the Key Innovation Team Project of Zhejiang Province, China (2009R50010).

Abstract:

Macroporous SiO2 monoliths were prepared via a sol-gel process accompanied by phase separation using a tetramethoxysilane (TMOS) precursor, 0.01 mol·L-1 HCl catalyst, propylene oxide (PO) gelation agent, and poly(ethylene oxide) (PEO, viscosity-averaged molecular weight (Mv): 10000) phase separation inducer. Monoliths were characterized by differential thermal analysis/thermogravimetry (DTA/ TG), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), mercury porosimetry, and nitrogen adsorption/desorption analysis (BET). The mechanism of the epoxide-mediated sol-gel reaction and PEO induced phase separation was discussed. The addition of PEO induced phase separation, and monolithic SiO2 with a cocontinuous macroporous skeletal structure was obtained at PEO/TMOS molar ratio of 0.0018. Monoliths had a narrow pore size distribution of 1-3 μm, surface area as high as 719 m2·g-1 and pore volume of 0.48 m3·g-1. This sol-gel transition is mediated by PO because of its strong nucleophilic properties and irreversible ring-opening reaction. Simultaneous phase separation is induced by PEO adsorbed on the SiO2 oligomers.

Key words: Porous monolith, Silica, Sol-gel, Phase separation, Propylene oxide, Poly(ethylene oxide)

MSC2000: 

  • O647