Ultratough, Processable Bioplastics Enabled by Triple Interlocking of Lignin and Cellulose

Sustainable and biodegradable bioplastics from natural lignocellulose offer a promising alternative to petroleum-based plastics, yet they often exhibit limited toughness and processability due to the inherent rigidity of polymer segments. Herein, we have developed a triple interlocking strategy to fabricate a high-strength, ultratough, and processable Bioplastic (denoted as CEL Bioplastic) from cellulose and lignin in the pulp/paper industry. In this process, we leverage room-temperature esterification of long-chain fatty acids with cellulose and lignin to produce a fully biobased CEL Bioplastic, distinguished by a robust triple-interlocking architecture that combines robust physical chain entanglements, cross-linked ester bonds, and densely packed hydrogen bonds. Physical chain entanglements in CEL Bioplastic efficiently distribute tension, while ester bonds and hydrogen bonds work synergistically to prevent chain disentanglement and enhance energy dissipation. The resulting CEL Bioplastic exhibits exceptional mechanical properties, with a tensile strength of ∼200 MPa, a fracture strain of ∼75% and an impressive toughness of ∼110 MJ/m³. These values are competitive to cellulose-lignin Bioplastic (denoted as CL Bioplastic) lacking long-chain entanglements and ester bonds, in tensile strength (15 times) but far exceed them in toughness (44 times). Moreover, long alkyl substituents exert an internal plasticizing effect, enabling CEL Bioplastics to form 3D structures through simple thermal or water-assisted shaping process. Such CEL Bioplastic exhibits biodegradability, recyclability and scalability (>4m in length), offering a sustainable pathway for producing high-performance bioplastics from natural biopolymers for functional and structural applications.