# Insights on the Influence of the Drying Method and Surface Wettability on the Final Properties of Silica Aerogels

## TL;DR

This paper explores how different drying methods and surface wettability affect the properties of silica aerogels.

## Contribution

The study provides insights into selecting drying methods based on gel wettability and desired aerogel properties.

## Key findings

- Four silica aerogel formulations with varying wettability were synthesized and analyzed.
- Three drying methods significantly influenced bulk density, porosity, and surface area of aerogels.
- Surface hydrophobicity/hydrophilicity directly correlates with the effectiveness of drying techniques.

## Abstract

In the synthesis of aerogels, the influence of the drying process on the nanostructure is an issue of utmost relevance for tailoring the final properties of these materials. Among the complex parameters affecting this process, the hydrophobicity of the aerogel structure plays a key role. Thus, herein, four different silica aerogel formulations based on tetraethyl orthosilicate and trimethoxymethylsilane were employed to produce aerogels with different wettability properties (from hydrophilic samples to highly hydrophobic). The synthesized gels were dried by three methods, namely freeze-drying, high-temperature supercritical drying with ethanol, and low-temperature supercritical drying with carbon dioxide, and the influence of each procedure on bulk density, porosity, pore size, and specific surface area of the resulting aerogels was analyzed in detail. The direct correlation between the surface hydrophobicity/hydrophilicity of the silica gels and the effects of each drying technique was analyzed, providing insights into a proper selection of the drying method depending on both the water affinity of the gel and the desired textural properties and structures.