Valorizing renewable cellulose from lignocellulosic biomass toward functional products

Cellulose is the largest natural and renewable biopolymer with biodegradability and biocompatibility and it has been considered as a promising feedstock for the clean production of functional materials, potentially contributing to a sustainable biomass-based economy. However, cellulose valorization is still hindered by the poor fractionation performance and the unsatisfactory solubility of cellulose. This review thereby summarized the state-of-the-art advances in the cellulose valorization from the aspects of the deconstruction and fractionation technologies, the clean solvent systems for cellulose dissolution, and the functional applications of sustainable products. The representative deconstruction technologies are crucial to overcome the biomass recalcitrance, alter the cellulose structure and thus improve the fractionation performance of cellulose. The dissolution behaviors of cellulose depended on the solvents systems employed, while the clean non-derivative solvent systems can improve the solubility of cellulose and form uniform cellulose solution. The regenerated cellulose from these solvent systems facilitated the preparation of functional materials, such as membranes, aerogels, microspheres, which had the promising potential to be used in the emerging fields of skin tissue engineering, carbon capture, and drug delivery. Mechanistic understanding of structure-property relationships indicated that the fractionation and dissolution technologies significantly altered the cellulose structures, such as crystallinity, and degree of depolymerization. which hence defined the functionality of cellulose-based materials. Overall, these findings highlighted that emerging green valorization technologies of cellulose will promote the clean production of environmentally friendly and sustainable materials, improve the economically viable cellulose valorization, and show the potential to contribute to carbon neutrality.