Nano-fibrillated cellulose-zeolites based new hybrid composites aerogels with super thermal insulating properties

- We prepared aerogels based on microcellulose, nanozeolites and nanocellulose.
- Nanocellulose/nanozeolith aerogels show super-insulation ability.
- Specific surface properties of nanocellulose explain the super-insulation.
- Nanozeolith induce improvement of stiffness of microcellulose aerogel.

Aerogel monoliths were prepared using combinations of cellulose microfibers, cellulose nanofibers and nanozeolites. It was shown that these hybrid materials have tunable thermal conductivity and mechanical properties. Thermal conductivity value as low as 18 mW m−1 K−1 was obtained that confirms the super-insulation ability of these new fibrous aerogels. Synergism on the thermal conductivity properties was shown by adjunction of nanozeolites to cellulose microfibrils by reaching pore size lower than 100 nm that significantly reduces the thermal conductivity of the hybrid aerogels as predicted by Knudsen et al. In one hand, these properties seem to depend strongly on the interactions between the component and their relative fractions. On the other hand, the addition of nanofibrils to micrometric fibers based aerogel yields a significant increase of its stiffness. The higher improvement of the stiffness was obtained when nanofibrils with high surface charge are added. This study certainly opens a new investigation field to optimize the thermal conductivity properties of hybrid nanocellulose based aerogels.