Construction and Nanostructure of Chitosan/Nanocellulose Hybrid Aerogels

Biomass aerogels have received extensive attention due to their unique natural characteristics. However, biomass-based chitosan aerogels are often confronted with the traditional issue concerning a weak skeleton structure, namely, the corresponding huge shrinkage for chitosan aerogels in the stage from the final gel to the aerogel. Herein, we put forward a new approach to enhance chitosan aerogels by introducing natural biomaterial cellulose nanocrystal (CNC). CNC is applied to connect/cross-link chitosan chains to form its networking construction through supramolecular interaction/physical entanglement, eventually realizing the enhancement of the chitosan aerogel network structure. Chitosan aerogels modified with CNC exhibit a high specific surface area of 578.43 cm2 g–1, and the pore size distribution is in the range of 20–60 nm, which is smaller than the mean free path of gas molecules (69 nm), triggering a "no convection" effect. Hence, the gaseous heat transfer of chitosan aerogel is effectively suppressed. Chitosan aerogels with the addition of CNC show an excellent thermal insulation property (0.0272 W m-1 K-1 at ambient condition) and an enhanced compressive strength (0.13 MPa at a strain of 3%). This improvement method of chitosan aerogel in enhancing the skeleton structure aspect provides a new kind of idea for strengthening the nanoscale morphology structure of biomass aerogels.