High-Performance and Energy-Efficient Nanolignocellulose Foams for Sustainable Technologies

There has been a recent surge of interest in biobased foams for applications ranging from building sustainability (insulation) to biomedicine, pharmaceutics, and electronics (scaffolds), with nanocellulose-based foams being particularly promising due to their porous and low-density structure. This study compares the production energy, structure, and properties of foams made from TEMPO-oxidized lignocellulose nanofibers (FTOLCNF) derived from unbleached wood pulp, and TEMPO-oxidized cellulose nanofibers (FTOCNF) from bleached cellulose pulp. Additionally, the incorporation of tannic acid (TA) as a biobased additive is explored for its ability to enhance the mechanical strength of FTOLCNF, contributing to improved performance. This builds upon the inherent advantages of FTOLCNF, which not only demonstrate superior structural integrity and load-bearing capacity (specific Young’s modulus of 37.4 J g–1, compared to 16.4 J g–1 for TOCNF) but also exhibit a higher yield during production due to the minimal processing required for unbleached pulp. Furthermore, FTOLCNF production requires about 18% less cumulative energy than FTOCNF (27 vs 33 MJ kg–1), largely owing to the energy-efficient preparation of TOLCNF from unbleached wood pulp. FTOLCNF also have a significantly lower cumulative energy demand (CED) compared to fossil-based alternatives like expanded polystyrene (EPS) and polyurethane (PU), highlighting their reduced environmental impact. Despite their lightweight nature, FTOLCNF exhibit competitive compressive strength, making them viable candidates for eco-friendly applications across various industries. Overall, this study demonstrates that FTOLCNF are an attractive alternative to other bio- and fossil-based foams, offering a balance of energy efficiency, higher yield, mechanical performance, and sustainability.