Adaptive Ionogel Paint from Room‐Temperature Autonomous Polymerization of α‐Thioctic Acid for Stretchable and Healable Electronics

Abstract Development of a universal stretchable ionic conductor coating on insulating substrates, irrespective of surface chemistry and substrate shapes, is of immense interest for compliant and integrative large‐area electronics but has proved to be extremely challenging. Existing methods relying either on the concurrent deposition of polymerizing precursors or on divided formulation and painting processes both suffer from several limitations in terms of adhesion, dehydration, processability, and surface pre‐treatment. Here an ionogel paint that is readily prepared from the concentration‐induced autonomous ring‐opening polymerization of a natural small molecule—α‐thioctic acid (TA) at ambient conditions is reported. The presence of ionic liquid prevents polyTA from further depolymerization via forming COOH···OS hydrogen bonds, resulting in ultra‐stretchable ionogels with widely tunable mechanical and conductive properties, self‐healability, as well as tissue‐like strain adaptability. Moreover, owing to its universal adhesion and adjustable rheology, the ionogel paint can be directly coated on diverse substrates with arbitrary shapes (including porous materials, 3D printed frames, and elastic threads) to render them ionic conductivity. Applications of the ionogel‐coated substrates as skin‐like highly sensitive and durable large‐strain sensors are further demonstrated, suggesting the ionogel paint's great potential in the emerging soft and stretchable electronics.