High-porosity aerogels of high specific surface area prepared from nanofibrillated cellulose (NFC)

Low-density aerogels based on nanofibrillated cellulose (NFC) from wood pulp were prepared from NFC aqueous dispersions using solvent exchange from water to tert-butanol followed by tert-butanol freeze-drying. In the present study, the dispersion of NFC nanofibers in the hydrocolloid was very well preserved in the aerogels. The “effective” diameter of the NFC nanofibers in the aerogels is around 10–18 nm corresponding to specific surface areas as high as 153–284 m2 g−1. Aerogels based on different NFC nanofibers were studied by FE-SEM, BET analysis (nitrogen gas adsorption), and mechanical properties were measured in compression for different densities of aerogels. The properties are compared with polymer foams and inorganic aerogels. Compared with cellular NFC foams, the present nanofibrous aerogels have lower modulus and show lower stress in compression for a given strain. Tert-butanol freeze-drying can therefore be used to create “soft” aerogels.

► Nanostructured and ductile NFC aerogels are made from wood cellulose nanofibers (NFC). ► NFC nanofibers are dispersed in tert-butanol, which is freeze-dried to a nanofiber network. ► The NFC nanofiber diameter is ≈10 nm and specific surface area as high as 153–284 m2 g−1. ► Modulus changes two orders of magnitude as aerogel density is varied from 14 to 105 kg m−3. ► NFC aerogels are in unoccupied space in materials property charts for modulus vs. density.