Cellulose is a highly promising resource in sustainable aerogel developments, but is less suited for insulation applications. Silica aerogels on the other hand are outstanding thermal insulators but often show insufficient mechanical properties like low stiffness and high brittleness. Aiming for improvement of both, the thermal properties of cellulose aerogels and the mechanical properties of silica aerogels, hybrid aerogel composites are of a special interest. For developing cellulose-silica aerogel composites using a "one-pot" approach, cellulose was dissolved using a salt hydrate melt based on cheap zinc chloride tetrahydrate and mixed with a silica sol based on tetraethylsilicate. The gelled cellulose-silica samples were regenerated in ethanol, dried with supercritical CO2 and characterized with respect to shrinkage, density, surface area, mechanical and thermal properties as well as micro-structure via SEM. The resulting cellulose-silica composites are white in colour and apparently homogeneous. Varying the ratios of both components yields a wide field of properties. The silica phase was shown to have a reinforcing effect on the cellulose aerogel by effectively increasing its Young's modulus. Furthermore, the resulting composites yield densities the range of 0.10–0.20 g cm–3 and specific surface areas in between 600 and 1000 m2 g–1 outlining an excellent combination of both gel components.

Easy process to cellulose-silica hybrid aerogels

253rd National Meeting (2017)

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