Fabrication of hydrophobic alumina aerogel monoliths by surface modification and ambient pressure drying

• Published in: Applied surface science 2010-08, Vol.256 (20), p.5973-5977
• Main Authors: Wu, Lina, Huang, Yudong, Wang, Zhijiang, Liu, Li, Xu, Huifang
• Format: Article
• Language: English
• Subjects: Aerogels; Alumina aerogel; Aluminum oxide; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Contact angle; Cross-disciplinary physics: materials science; rheology; Drying; Exact sciences and technology; Hydrophobic; Morphology; Physics; Porosity; Pressure; Siloxane; Solvents; Surface modification; Thermogravimetry
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2010.03.104

Hydrophobic crack-free alumina aerogel monoliths were fabricated by –Si(CH 3) 3 (trimethylsilyl substituent) modification of alcogels followed by an ambient pressure drying procedure. One-step solvent exchange and surface modification were simultaneously progressed by immersing alumina alcogels in trimethylmethoxysilane (TMMOS)/hexane solution. It is found that the hydrophobic property of alumina aerogels is affected by the contents of TMMOS from the measurements of contact angle and Fourier transform infrared spectrometry. Thermogravimetry/differential scanning calorimetry analyses reveal that the modified aerogels maintain their hydrophobic behavior up to a temperature of 260 °C. The structure and morphology of the obtained hydrophobic alumina aerogels were characterized by the measurements of N 2 physical adsorption and scanning electron microscopy, which showed that they were highly porous materials with narrow slit-like pore geometry and a high degree of pore size uniformity.