Regulation of Lignin Microstructures to Construct Fully Biomass-Based Elastomers for Large Crack Self-Healing Artificial Muscles

Abstract

Self-healing elastomer-based artificial muscle has attracted growing attention due to their potential applications in various fields. However, the development of self-healing artificial muscles from biomass raw materials, capable of repairing large cracks at the millimeter scale remains a significant challenge. In this study, a novel lignin-based all-biomass elastomer is synthesized via a solvent-free, one-pot melting method. Thioctic acid (TA) undergoes ring-opening copolymerization with itaconic acid (IA) at elevated temperatures, forming a flexible polymer matrix. Enzymatic hydrolysis lignin (EHL) achieves exceptional dispersion in molten TA, followed by in situ cross-linking through metal coordination and hydrogen bonding. This resultant nano-enhanced interlocking dual-network structure endows the elastomer with high flexibility, stretchability, and self-strengthening capabilities through mechanical training, closely mimicking the behavior of biological muscles. Most importantly, such an elastomer demonstrates remarkable shape memory function and intrinsic self-healing ability, coupled with its photothermal properties, which facilitate the self-repair of millimeter-scale cracks. Thus, this study develops a novel strategy for lignin microstructure regulation and constructs a fully biomass-based elastomer for millimeter-scale self-healing artificial muscle, which not only addresses the challenge of self-healing scale but also achieves a breakthrough in the high-value utilization of lignin.