Self-Assembly and Properties of Elastic Nanocellulose-Carbon Airgel with Ordered Porosity by Template-Free Directional Freezing

Abstract

Porous cellulose aerogels with different compositions have been fabricated via three methods, including regular freezing, directional freezing, and hydrothermal treatment, using pure cellulose oxide and cellulose oxide/graphite oxide composites, respectively. The cellulose aerogels are highly elastic and light in weight. The carbon aerogels show an ordered structure through directional freezing with layered skeleton bones and some folds. Unlike low-temperature freezing, the structures can obtain elastic properties. When the deformation is 20%, carbon aerogels can rebound to 95% of their original volume. The cellulose oxide/graphite oxide composite aerogels are synthesized into carbon–aerogel composites, which also have stable and robust structures of bone skeletons due to nanosheets. The carbon–aerogel composites have more than 85% resilience under 40% deformations. Carbon aerogels prepared from nanocelluloses have a novel three-dimensional network structure and have the application of elasticity, which is expected to be applied to metallurgical technology and the aerospace field. Through directional freezing, the carbon aerogels have regular structures of layered skeleton bones with some folds. In contrast to low-temperature freezing, the structures possess excellent elastic properties.