Deep eutectic solvents as a ‘multifunctional operating platform’ for nanocellulose production and modification: A review on sustainable composite advancements

Nanocellulose, valued for its renewability, biodegradability, and mechanical strength, holds great promise for sustainable technologies. However, its dense hydrogen-bonded structure hinders efficient nanofibrillation and functionalization. This review highlights deep eutectic solvents (DES) as a novel ‘multifunctional operating platform’ (MOP) for nanocellulose preparation, modification, and applications. DES systems uniquely disrupt hydrogen bonding in cellulose, enhancing hydroxyl (-OH) group accessibility and enabling efficient nanocellulose production under mild conditions. By tuning DES composition and processing conditions, control nanocellulose morphology can be precisely controlled to yield cellulose nanofibers (CNFs) or cellulose nanocrystals (CNCs) with tailored properties. DES also enables one-pot functionalization—including esterification, cationization, and grafting—streamlining processes that typically require harsh conditions. This integrated strategy overcomes key limitations of traditional methods, offering a greener, more efficient pathway to modified nanocellulose. Applications in composites, elastomers, hydrogels, and films demonstrate enhanced mechanical performance, stability, and compatibility, unlocking potential in flexible electronics, packaging, and advanced materials. The review highlights the transformative role of DES in nanocellulose engineering and outlines future directions for expanding its utility in sustainable, high-performance material science.