Functional Modification of Chitosan Films: Influence of Chitosan Molecular Weight and Acidic Medium Type

The packaging industry relies on plastics as multipurpose materials. However, there is a growing effort to identify alternatives with comparable properties while being environmentally friendly. In this context, chitosan‐based films represent a promising class of sustainable materials due to their characteristics. This work focused on the influence of chitosan molecular weight and acid type on the barrier, optical, and mechanical properties of chitosan films. The films were prepared from two low molecular weight, one medium molecular weight, and one high molecular weight chitosan. Acetic, citric, and lactic acid, either individually or in combination, were used as solvents. The functional properties of the prepared films were characterized by measuring the films' thickness, water vapor permeability coefficient, oxygen permeability coefficients under dry and moist conditions, optical transmittance, and tensile properties. The results demonstrated how the final films' properties can be significantly altered solely by modifying the basic composition of the formulation and the characteristics of the components. The molecular weight of chitosan, as well as the type and concentration of the acid, had a pronounced effect on all measured properties. Through these modifications, the final films can be tailored to meet specific requirements for packaging.