Choline Chloride Versus Choline Acetate: Anion Influence on Plasticizing Action in Starch/Chitosan Blends

Biopolymers have gained importance in various sectors such as biomedical, automotive, and agriculture, as well as in single-use food packaging. However, to make them competitive with traditional plastics, biopolymers require certain modifications, including the addition of plasticizers and/or blending with other macromolecules. This study aims to develop biodegradable films using starch blended with chitosan, plasticized by choline chloride [Ch][Cl], and choline acetate [Ch][OAc], an ionic liquid derived from choline. The decision to exploit the plasticizer ability of bio-based ionic compounds depends on their excellent properties, such as non-volatility, biodegradability, and low toxicity. The research evaluates the effects of varying starch and chitosan fractions, as well as the two plasticizers, on the properties of the resulting films. Morphology, chemical composition, crystallinity, mechanical properties, thermal stability, and wettability are evaluated through different techniques, such as scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis, thermogravimetric analysis, and performing mechanical and wettability tests. Characterization analyses highlight the primary influence of the anion on the properties of the different blends, suggesting the greater plasticizer capacity of the acetate anion.