Ultralight, Hydrophobic, Fire-Resistant, and Highly Thermally Insulating Aerogel by Cross-Linking Cellulose Nanofiber with Tannin and Adenosine Triphosphate

Although cellulose nanofiber (CNF) aerogels have promising applications in fields such as thermal insulation, adsorption, and separation, their use has been restricted because of their limited mechanical stability and flammability. To overcome these limitations, this study utilizes the unique properties of tannic acid (TA) and adenosine triphosphate (ATP) biomolecules to fabricate a synergistic TA/ATP/CNF aerogel with exceptional features such as ultralightness, hydrophobicity, lipophilicity, fire resistance, and high thermal insulation. With a low density of 6.13 mg·cm–3, thermal conductivity of 0.12 W·m–1·K–1, and high limiting oxygen index of 30.5%, the TA/ATP/CNF aerogel outperforms other state-of-the-art aerogels, including CNF-based aerogels. The study also presents a computational algorithm using Python 3.6 to analyze the aerogel's highly porous structure. Owing to its lipophilic properties, the TA/ATP/CNF aerogel is a promising porous adsorbent capable of rapidly adsorbing oil/organic solvents while exhibiting excellent flame retardancy, even when saturated with oil. This study highlights the potential of using natural biomolecules to improve the properties of CNF aerogels, making them suitable for various applications such as thermal insulation, adsorption, and separation.