Dissolution of chitosan with low degradation enabled by aqueous amino acid salt solutions at room-temperature

The efficient dissolution of chitosan (CS) is an essential prerequisite for high-value-added applications. However, conventional solvents are plagued by high viscosity, notable CS degradation, and an unclear dissolution mechanism. Herein, two aqueous nitrate-based amino acid salt solutions-glycine nitrate ([Gly]NO₃) and proline nitrate ([Pro]NO₃) systems-were employed to dissolve CS at room temperature. Spectroscopic analysis and molecular dynamics (MD) simulations of the [Gly]NO₃ system suggest that the dissolution process is primarily driven by the protonation of amino groups, which disrupts the intra- and inter-molecular hydrogen bond networks of CS while simultaneously strengthening its interactions with [Gly]NO₃. The structure-property relationship between amino acid-based ionic liquid (AAILs) and regenerated chitosan (RCS) degradation was investigated under various dissolution conditions, revealing that the [Pro]NO₃ system induces less polymer degradation than the [Gly]NO₃ system. Using aqueous [Pro]NO₃ salt solution as the solvent, regenerated chitosan fibers (RCFs) were successfully fabricated via microfluidic wet-spinning. The resulting fibers were characterized by a dense morphology and acceptable mechanical properties (tensile strength: 1.51 cN·dtex^-1; elongation: 3.50%).