Research progress and prospects of novel green solvent systems for chitin and chitosan and their functionalized materials

Chitin and chitosan, as abundant natural polymers, have attracted considerable attention in sustainable development due to their excellent biocompatibility, biodegradability, and multifunctionality. However, their poor solubility caused by strong hydrogen bond networks and high crystallinity severely restricts their high-value utilization. This review systematically summarizes the research progress of novel solvent systems for chitin/chitosan and their applications in functional material preparation. First, we review the development history of traditional solvent systems and analyze their inherent limitations. Subsequently, we thoroughly discuss the dissolution mechanisms of novel green solvents including ionic liquids, deep eutectic solvents, and alkaline aqueous solvents. We highlight the application potential of functional materials prepared from these new solvent systems in environment, energy, and biomedicine. Finally, addressing technical bottlenecks in solvent safety assessment, low-energy continuous processing, and digital intelligent manufacturing, we propose circular economy-driven sustainable development pathways. This review provides theoretical guidance and technical references for promoting the green and efficient utilization of chitin/chitosan resources.