The role of a deep eutectic solvent in changes of physicochemical and antioxidative properties of chitosan-based films.

In this work deep eutectic solvent (DES), based on the mixture of choline chloride and lactic acid, were suggested as chitosan films plasticizers. The molecular structure and properties of films obtained using chitosan, with different degree of deacetylation and 0-80 wt.% DES content (ωDES), were studied by means of FTIR spectroscopy, SEM and AFM microscopy (films' surface properties) together with optical characteristics, water vapor transmission rate (WVTR), water vapor permeability (WVP), tensile strength (TS) and elongation at break (Eb). Scanning electron micrographs revealed that all chitosan-DES films were smooth and uniform. DES significantly improves the film flexibility (Eb increases of ca. 160 % after incorporation of 80 wt.% DES), slightly decreases tensile strength and also improves antioxidative properties while simultaneously, increasing water vapor permeability (WVP). Films prepared in this study exhibit characteristics that qualify them for potential use as an active packaging material.