Chitosan/Poly(Itaconic Acid) Films via In-Situ Radical Polymerization: Insights into Morphology, Structure, Mechanical, and Water Resistance Properties

Abstract Chitosan (CH) is a biopolymer with strong potential for sustainable food packaging applications. However, this is hindered due to its poor water resistance and limited mechanical performance. To overcome these limitations, this study proposes an easy modification strategy based on the in-situ radical polymerization of itaconic acid (IA) directly within the CH film-forming solution, resulting in CH-based films incorporating poly(itaconic acid) (PIA) in a single step. The incorporation of 10% IA increased the water contact angle from 87.3° to 92.3° and reduced moisture content from 23.8 to 21.1%. Thermal stability was improved, and tensile strength increased by approximately 50% compared to the unmodified film. These enhancements are attributed to intermolecular interactions and partial grafting of PIA chains onto CH, as supported by FTIR, XRD, and SEM analyses. Hence, the direct synthesis of PIA during film formation offers a simple yet effective modification of CH, enhancing water resistance, thermal stability, and mechanical properties, positioning CH/PIA films as strong candidates for food packaging applications.