Foams and aerogels based on nanopolysaccharides

Nanopolysaccharides, including nanocelluloses and nanochitin, self-assemble in aqueous solution and form gel networks, supramolecular inclusion complexes and other structures that adsorb at the oil/water and air/water interfaces. As such, they are ideally suited to stabilize multiphase systems such as Pickering emulgels and foams where the nanopolysaccharides bring their own functionalities. The latter can be extended by surface chemical modification or by combination with surfactants or polymers. Hence, it is possible to create stimuli-responsive, tailorable, and/or active functional bio-based materials suitable in a range of applications. We describe the chemistry, structure, and physicochemical properties of nanocellulose and deacetylated nanochitin for the synthesis of light-weight materials. We show the possibility of anisotropic and chiral nematic arrangement of cellulose nanocrystals to produce aerogels with opto-mechanical properties. In further developments, we describe 3D structured hybrid aerogels via liquid-liquid sculpting in which an elastic film formed at the interfaces of immiscible liquids leads to elastic structures with a highly porous honeycomb arrangement that is highly conductive upon thermal annealing and attenuate most of the incident EM waves. The aerogels act as perfect thermal insulators and infrared shields capable of preventing heat transfer, leading to effective energy saving and infrared shielding.