Biomass-derived γ-valerolactone (GVL) for use in organic electrolyte solutions: a benign platform for chitin dissolution and processing

Chitin dissolution is prerequisite to allow its homogeneous processing and develop value-added regenerated/derivative chitin-based materials. In this work, in combination of [EMIM][OAc] ionic liquids, biomass-derived γ -valerolactone (GVL) was delicately screened as a co-solvent to construct benign organic electrolyte solutions (OESs) for chitin dissolution and homogeneous processing. Kamlet-Taft parameters ( α , β , and π*) of [EMIM][OAc]/GVL OESs with varying molar ratios are examined. Introduction of [EMIM][OAc] into GVL can notably increase the polarity, supported by the increased E T (30) values. The NMR studies of N -acetylglucosamine (GlcNAc, the repeating unit of chitin) solvation further indicate that the hydrogen bonding between GlcNAc and both the anions and cations of the ILs. Rheological properties of chitin/[EMIM][OAc]/GVL solutions are studied, and lower viscous activation energy ( E η ) accompanies the increase of GVL content in the OESs, as the addition of GVL reduces the energy barrier for viscous flow and facilitates the mobility of chitin molecular chains. Furthermore, the potential of the chitin solutions for homogeneous processing into films is primarily demonstrated via a conventional solution casting approach using water as the coagulation bath. Regenerated chitin films are systematically characterized by FTIR, NMR, XRD, TGA, UV–vis, SEM and tensile tests. Thus, it seems that the [EMIM][OAc]/GVL OESs present a green platform for fabricating chitin-based materials.