Converting natural biopolymers to sustainable bioplastics <i>via</i> structure engineering

Sustainable bioplastics have attracted considerable attention as alternatives to conventional petroleum-based plastics in response to growing concerns about resource depletion and environmental pollution. Natural biopolymers, such as starch, cellulose, and chitin/chitosan, are emerging as promising candidates for bioplastic production due to their widespread availability and biodegradability. This review conducts a comprehensive examination of recent advances in polymer-level structural engineering of natural biopolymers into bioplastics, with a focus on strategies that introduce intermolecular interactions, including permanent covalent bonds, dynamic covalent linkages, and noncovalent interactions, to reconstruct intrinsic hydrogen-bonded networks. This reconstruction provides the basis for converting natural biopolymers into bioplastics with permanent covalent, dynamic covalent, and physically crosslinked architectures, and the ways in which these architectures affect material properties, processability, and overall performance are systematically assessed. Additionally, the review discusses the direct utilization of raw lignocellulosic biomass as a potential approach to enhance the cost-effectiveness and scalability of bioplastic production. Finally, the challenges in developing high-performance bioplastics are examined, along with future perspectives for advancing bioplastics in alignment with circular economy principles and carbon neutrality objectives.