Gradual Concentration‐Regulated Entanglement Enables Tough and Strong Sustainable Bioplastics

ABSTRACT Regulating polymer‐chain entanglement provides a powerful route to high‐performance sustainable bioplastics. However, achieving dense entanglement in ultrahigh‐molecular‐weight polymers remains difficult because long chain lengths and strong intramolecular interactions suppress interchain interpenetration, ultimately limiting mechanical performance. Here we introduce a gradual concentration‐regulation strategy that progressively amplifies trapped entanglements, followed by photochemical crosslinking to preserve the entangled state within a robust multinetwork architecture. The resulting bioplastics combine mechanical properties that surpass those of conventionally processed counterparts and approach those of commercial plastics, while maintaining high mechanical stability, environmental adaptability, and on‐demand degradability under mild conditions. As a proof of concept, we integrate these materials into soft electronic devices capable of emotion‐responsive sensing and remote actuation. These devices are fully transient, enabling programmed degradation via enzymatic or chemical pathways over timescales ranging from hours to months, thereby addressing end‐of‐life disposal challenges. This work establishes a scalable and broadly applicable strategy for engineering high‐performance sustainable polymer systems for advanced materials and bioelectronic applications.