Simultaneous Wall-Pore Formation and Hydrophobization of Superelastic Chitin Nanofiber/Chitosan Aerogels

Abstract This study successfully prepared a low-density, superelastic, hydrophobic chitin nanofiber/chitosan/alkyl ketene dimer (ChNF/CS/AKD) composite aerogel for efficient oil–water separation by using AKD emulsion as the melt-processable pore-forming agent and hydrophobizing component. A three-dimensional network framework was constructed based on rigid ChNF and flexible CS, integrated with unidirectional freezing technology to form an ordered honeycomb-like pore structure. The innovative incorporation of AKD emulsion achieved in situ pore formation and surface hydrophobization simultaneously via controlled thermal treatment. By regulating the CS/ChNF ratio, density, AKD content, and average particle size of emulsion, the optimal aerogel exhibits high resilience and fatigue resistance (only 1.70% plastic deformation after 1,000 cycles at 70% strain). In addition, the composite aerogel demonstrates significant hydrophobicity (water contact angle of 138.60°) with adsorption capacities for various oils and organic solvents ranging from 57.27 to 125.33 g/g. After 20 cycles, the adsorption retention exceeds 90% with stable mechanical properties. This study provides insights into structural design and performance regulation for high-performance biomass aerogels.