Nanocellulose Aerogels

With the advent of the green economy, the most abundant and renewable polymer on Earth, cellulose, holds, once again, academia and industry’s attention. The biodegradability, biocompatibility, and low density of cellulose have always been the main assets in the development of aerogels. However, with the rapid emergence of a new family of cellulose, so-called nanocellulose or cellulose nanomaterials (CNMs), the application field of bio-based aerogels is rapidly expanding. CNMs are nano-sized cellulose particles produced from any kind of cellulose sources by either biological synthesis or chemical or physical routes. Their high aspect ratio, large surface area, tunable surface chemistry, high strength, and low density are many ideal characteristics for the elaboration of sustainable, lightweight, and functional mesoporous solids. This chapter gives an overview on CNM aerogel processing, properties, and applications. CNM aerogels can be obtained from hydro- or alcogel by either supercritical CO2 drying or ice templating, two techniques that can be used to produce lightweight, highly porous aerogels (>99%) with large specific surface area (>100 m2/g). This chapter discusses the high compressive strength and superinsulation properties of CNM aerogels, which paves the way for future high-value applications. Possibilities in functionalization of CNMs for their controlled interaction with other nano-sized particles and/or biopolymers have significantly broadened the applications of CNM aerogels spanning from bio-based adsorbents, biomedical scaffolds, and insulation materials to carbon aerogels, energy-storage devices, or inorganic templates. This chapter illustrates a few of these promising application areas and highlights remaining challenges to address for advancing commercialization of CNM-based aerogels.