Hydrophobic and thermal-insulating aerogels based on rigid cellulose nanocrystal and elastic rubber.

Inspired from the ancient China philosophy of "coupling hardness with softness", we attempted the combination of rigid cellulose nanocrystals (CNC) and elastic rubbers to solve the limitations of structural brittleness and water sensitivity of CNC-based aerogels. Three rubber chains with the different chemical structures (silicon rubber, 1,2-polybutadiene, styreneic block copolymer) were covalently bonded on the CNC porous skeleton based on thiol-ene click chemistry, to fabricate the CNC/rubber composite aerogels. With the introduction of moderate loading levels of rubber, the composites aerogels exhibited low density and shrinkage, high porosity and specific surface area and improved mechanical performance. Furthermore, the presence of rubber components completely changed the hydrophilic nature of cellulose skeleton as the hydrophobic aerogels, contributing the superior solvents resistance and self-cleaning property. With their advantages on mechanical stability, heat insulation and hydrophobicity, the fabricated aerogels in this study exhibited the high added values in various potential applications.