Ambient pressure dried silica aerogel – Melamine foam composite with superhydrophobic, self-cleaning and water remediation properties

Abstract

With their low density, high surface area and thermal insulation properties, silica aerogels are proper candidates for water remediation or thermal insulation applications. However, their fragility, lengthy and costly fabrication process restricts their application. The inclusion of a flexible melamine foam (MF) along with a co-precursor system consisting of monomeric methyltrimethoxysilane (MTMS) and polymeric polyvinyltrimethoxysilane (PVTMS) can make the fabrication process feasible and improve the durability of aerogels. Also, PVTMS with a doubly-crosslinked network brings mesoporous structure and high surface area to MF. MTMS alters the hydrophilic nature of MF to superhydrophobic, without surface modification steps.Varying concentration of PVTMS and MTMS were used to fabricate the MF- aerogel composite. Acid and base catalysts were used for the hydrolysis and condensation. The MF-aerogel composite was obtained using ambient pressure drying, and the overall fabrication process took around 48 hrs.The inclusion of MF enabled the ambient pressure drying and brought flexibility for silica aerogels. On the other hand, the presence of mesoporous aerogels improved the thermal insulation properties of MF (λ ∼ 0.027 W·m−1·K−1), making it superhydrophobic (θ ∼ 160°), self-cleaning, and moisture resistant. Excellent oil adsorption (up to 36 g·g−1) and oil–water separation performance (oil flux of 120,000 L·m−2·hr−1) of MF-aerogel composite were also confirmed.