Original Paper

Journal of Sol-Gel Science and Technology

, Volume 49, Issue 3, pp 285-292

Synthesis of transparent silica aerogels with low density and better hydrophobicity by controlled sol–gel route and subsequent atmospheric pressure drying

  • Poonam M. ShewaleAffiliated withAir Glass Laboratory, Department of Physics, Shivaji University
  • , A. Venkateswara RaoAffiliated withAir Glass Laboratory, Department of Physics, Shivaji University Email author 
  • , A. Parvathy RaoAffiliated withAir Glass Laboratory, Department of Physics, Shivaji University
  • , S. D. BhagatAffiliated withAir Glass Laboratory, Department of Physics, Shivaji University

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Abstract

In the present paper, attempts have been made to produce transparent silica aerogels with low density and better hydrophobicity by controlled sol–gel route and subsequent atmospheric pressure drying. The hydrogels were prepared by hydrolysis and polycondensation of sodium silicate (Na2SiO3) in the presence of acetic acid catalyzed water followed by several washing steps with water, methanol and hexane, respectively. The surface modification of the wet gel was carried out using a mixture of hexamethyldisilazane (HMDS) in hexane. Since, the sol–gel chemistry provides a straightforward method to control the physical and optical properties of the aerogels, the influence of various sol–gel parameters viz. gel washing time, molar ratios of CH3COOH/Na2SiO3 and HMDS/Na2SiO3 and silylation period on the physical and optical properties of the aerogels have been investigated. The aerogels have been characterized by bulk density, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetric and Differential Thermal Analysis (TG-DTA), Atomic Absorption Spectroscopy (AAS), Scanning Electron Microscopy (SEM) studies and Contact angle measurements.

Keywords

Sodium silicate Ambient pressure drying Aerogel Hydrophobic Transparent