Dual-enhancement effect of electrostatic adsorption and chemical crosslinking for nanocellulose-based aerogels

Nanocelluloses including rigid cellulose nanocrystals (CNC) and semi-flexible cellulose nanofibrils (CNF) have recently gained much attention as the high-added nanomaterials from renewable resources. These nanoparticles with high aspect ratio are widely used as reinforcing agents in composites and porous materials. In this study, a dual-enhancement strategy based on the electrostatic adsorption and chemical crosslinking was proposed to improve the mechanical properties of composite aerogels based on the combination of TEMPO-oxidized CNF and cationic CNC aided with sodium alginate (SA) and crosslinked by three isocyanate reagents. The resultant aerogels are ultralight ( < 0.06 g/cm(3)), highly porous ( > 96%) and hydrophobic materials (water contact angle > 100 degrees), with the simultaneous increase of compression modulus, compression strength and compression energy by three orders of magnitude. The dual-enhancement strategy developed in here presents a novel approach to design the nanocellulose-based porous materials with remarkable enhancement of mechanical properties and potential applications in diverse functional materials.