Eco-Friendly Ionogel with Bioderived Thioctic Acid and Cellulose: Integrated Toughness, Self-Healing, and Recyclability

Ionogels represent a promising class of materials for applications in flexible electronics, such as wearable sensors and human motion monitoring. Here, a multifunctional ionogel is developed through the synthesis of a microcrystalline cellulose (MCC)-reinforced poly(thioctic acid) gel (MRG), which integrates high toughness, autonomous self-healing, and strain-sensing functionality. The material is constructed via the thermal ring-opening polymerization of thioctic acid, dynamically cross-linked by Zn2+ coordination and reinforced with MCC. Structural characterization confirms the successful formation of a hierarchical dynamic network comprising disulfide bonds, metal coordination, and hydrogen bonding. The resulting ionogel exhibits outstanding mechanical properties, with fracture strain exceeding 14,500% and a tensile strength of 0.68 MPa, alongside excellent fatigue resistance over 300 cycles. It also demonstrates efficient self-healing, achieving 70.6% mechanical recovery within 5 h and full crack closure in 60 min at room temperature. The gel functions as a highly sensitive strain sensor capable of monitoring human joint movements with an angle-dependent electrical response. Additionally, the material enables closed-loop recycling via an eco-friendly hot-pressing method, effectively minimizing environmental impact while embodying green design concepts. These integrated properties stem from the synergistic dissociation and reorganization of dynamic covalent and noncovalent bonds within the MCC-enhanced network. This work successfully developed a tough, self-healing, recyclable, strain-sensing ionogel composed of bioderived thioctic acid and microcrystalline cellulose.