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Journal of Non-crystalline Solids

Journal of Non-crystalline Solids

IF: 3.2
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Superhydrophobic silica aerogels based on methyltrimethoxysilane precursor

Published:15 November 2003 DOI: 10.1016/j.jnoncrysol.2003.08.048
A. Venkateswara Rao , Manish M. Kulkarni , D.P. Amalnerkar , Tanay Seth

Abstract

The experimental results on the synthesis and physicochemical properties of superhydrophobic silica aerogels, with the highest ever obtained contact angle (~173°), using methyltrimethoxysilane (MTMS) precursor, methanol (MeOH) solvent and ammonium hydroxide (NH4OH) catalyst, are reported. The molar ratios of NH4OH/MTMS (N), H2O/MTMS (H) and MeOH/MTMS (M) were varied from 4.25?×?10?2 to 3.5?×?10?1, 2 to 10 and 1.75 to 17, respectively. It has been found that the gelation time decreases with increase in N and H values and it increases with increase in M values. The bulk density of the aerogels was found to decrease with increase in N, H and M values. It has been observed that the volume shrinkage increases with decrease in N and H values and increases with M values. In the case of catalyst concentration variation, the contact angle (θ) increases slightly from 159° to 167° with increase in N values. On the other hand, in the case of H2O and MeOH variations, the θ first increases from 162° and 160° up to the values of 173° and 167° and then decreases to 160° and 159° with increase in H and M values, respectively. All the MTMS aerogels are opaque to the visible light. The aerogels retain their hydrophobicity up to a temperature of ~480 ° C. The thermal conductivity of the aerogels was found to be around 0.095 W/m?K except for the aerogels with higher bulk density (>0.3 g/cm3, at a lower H value of 2) whose thermal conductivity was around 0.109 W/m?K. The aerogels have been characterized by Fourier transform infrared spectra (FTIR), thermogravimetric and differential thermal analyses (TGA-DTA) and scanning electron microscopy (SEM) techniques. The results have been discussed by taking into account the hydrolysis and condensation reactions and SEM observations.

Substances (4)

Related products
Procduct Name CAS Molecular Formula Supplier Price
Methanol 67-56-1 CH4O 896 suppliers $9.00-$7620.00
Ammonium hydroxide 1336-21-6 H5NO 790 suppliers $14.56-$2190.00
2-Methoxyethanol 109-86-4 C3H8O2 630 suppliers $7.62-$7070.00
Methyltrimethoxysilane 1185-55-3 C4H12O3Si 561 suppliers $6.00-$940.00

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