Fabrication of hydrophilic and hydrophobic silica aerogel by drying‎ at ambient pressure and their structural properties

Abstract

In this research, silica aerogel was made by sol-gel method with sodium silicate precursor ‎and drying at ambient temperature. The silica aerogel prepared by this method is ‎superhydrophobic. To make it hydrophilic, the sample was heated at 400 °C for 2 h. The ‎structure of the samples was studied using X-ray diffraction, scanning electron microscopy, ‎adsorption and desorption of nitrogen gas. To investigate the hydrophilicity and ‎hydrophobicity of the samples, the water droplet contact surface test was performed. The ‎chemical bonds of the prepared samples were studied using Fourier transform infrared ‎spectroscopy. The overall results showed that the size of the particles and the pores increase ‎and become smaller, respectively when the hydrophilicity of the silica aerogel sample ‎changes to the hydrophobic sample. The angle of contact of the water droplet with the ‎surface of the hydrophobic sample is 170°, while reaches to 51° for the hydrophilic sample‎.