B. Chen, T. Li
University of Maryland College Park,
United States
Keywords: bioplastic, sustainability, recyclability, biodegradability, mechanical properties
Summary:
The widespread use and disposal of petroleum-derived plastic films contribute significantly to environmental pollution, affecting water, soil, and air pollution and leading to microplastic contamination. In response, extensive efforts have focused on reducing plastic pollution and energy consumption by enhancing recyclability and developing eco-friendly alternatives, such as natural polymer-based packaging films for food and beverages, biomass-based foams for atmospheric water harvesting, and wood-based materials as substitutes for plastics. Natural polymer-based films offer the advantages of renewability, sustainability, non-toxicity, and environmental friendliness. However, their mechanical properties often limit their direct replacement of flexible plastics, such as polyethylene and polypropylene. Thus, improving the ductility and strength of natural polymer-based films is essential. Extensive efforts have been made to develop biodegradable chitosan-based films with enhanced mechanical properties as alternatives to conventional plastics. However, balancing ductility and strength in chitosan-based materials remains a significant challenge because these two mechanical properties are intrinsically mutually exclusive. This study presents a facile strategy for fabricating chitosan/polyurethane nanoparticles (PU NPs) bioplastic films that simultaneously enhance both ductility and strength. The chitosan/PU NPs bioplastic film exhibits a unique elastic node-grid structure, where PU NPs serve as the crosslinkers (elastic nodes) within an entangled chitosan network. The remarkable mechanical properties are attributed to the deformation of the elastic nanoscale PU NPs under load and dynamic hydrogen bonding interactions between PU NPs and chitosan molecules. Furthermore, the bioplastic film is recyclable through a simple process without noticeable loss of mechanical performance and is compostable and biodegradable in soil within three months. This innovative bioplastic film holds promise for developing strong, ductile, and tough biopolymer materials, paving the way for sustainable alternatives to plastic film alternatives and diverse future applications.