Stretchable, Self-Healing, and Processable Bioelastomers Enabled by Highly Branched Cross-Linking Networks for Flexible Electronics

Stretchable elastomers require a stretchability exceeding 200% and a Young's modulus ranging from 0.1 to 10 MPa to balance strength and extensibility for dynamic applications. Conventional petrochemical polymers meeting these criteria rely on covalent networks, which lack mechanical tunability and face challenges in terms of repairability and recyclability. Here, we introduce a highly dynamic covalent branched network to fabricate a polyimine elastomer (PIE) featuring extensive mechanical tunability, controllable self-healing properties, reprocessability, and recyclability. This PIE is synthesized at room temperature from a lignocellulose-derived dialdehyde prepolymer (dialdehyde-terminated prepolymer) and cross-linked with a triamine via imine bonds. The resulting PIE, characterized by dynamic covalent networks, presents a skin-friendly Young's modulus of less than 3 MPa and an impressive stretchability of strain exceeding 1,110%. Additionally, PIE exhibits direct thermal reprocessability at 100 °C within 15 min, enabling transformation into various forms, along with self-healing capability. Flexible electronics utilizing the PIE substrate demonstrate appealing stretchability, high sensitivity, and recyclability. This biomass-derived highly branched cross-linking network likely provides a promising approach for designing high-performance bio-based synthetic elastomers, contributing to the advancement of sustainable flexible electronic devices.