Enhanced Mechanical Stability and Hydrophobicity of Cellulose Aerogels via Quantitative Doping of Nano-Lignin

As a porous biomass sustainable material, cellulose aerogel has attracted significant attention due to its unique properties in various applications. However, its mechanical stability and hydrophobicity are huge obstacles hindering practical applications. In this work, nano-lignin quantitative doping cellulose nanofiber aerogel was successfully fabricated via liquid nitrogen freeze drying combing vacuum oven drying. The impact of various parameters (lignin content, temperature, and matrix concentration) on the property of the as-prepared materials was systematically explored, revealing the optimum conditions. The morphology, mechanical properties, internal structure, and thermal degradation of the as-prepared aerogels were characterized by various methods (compression test, contact angle, SEM, BET, DSC, and TGA). Compared with pure cellulose aerogel, the addition of nano-lignin did not significantly change the pore size and specific surface area of the material but could improve its thermal stability. In particular, the enhanced mechanical stable and hydrophobic properties of cellulose aerogel via the quantitative doping of nano-lignin was confirmed. The mechanical compressive strength of 160-13.5 C/L-aerogel is as high as 0.913 MPa, while the contact angle was nearly reaching 90°. Significantly, this study provides a new strategy for constructing a novel cellulose nanofiber aerogel with mechanical stability and hydrophobicity.