Strong, highly porous and sustainable nanocellulose foam made using bioderived hyperbranched crosslinker for thermal insulation and sound absorption

This paper reports an environment-friendly biobased foam made with cellulose nanofiber (CNF) and a biobased hyperbranched crosslinker, glycerol succinic anhydride (GSA). As a biobased hyperbranched crosslinker, carboxyl-terminated GSA is synthesized through a straightforward esterification process involving glycerol and succinic anhydride. The GSA-crosslinked CNF (GSA/CNF) foam is prepared using a facile, sustainable, cost-effective, and efficient solvent-exchange method. The resulting foam exhibits notable characteristics, including improved dimensional stability, remarkably low density (13.41 mg/cm(3)) with high porosity (>99 %), and exceptional compressive strength (494 kPa) and modulus (452 kPa). Further, the foam offers outstanding sound absorption capabilities with a coefficient of 0.986 at 2 kHz and remarkably low thermal conductivity (30.18 mW/mK), significantly lower than commonly used and reported porous materials, indicating its potential as an efficient, environmentally friendly sound absorption and thermal insulation material.