Potential applications of flexible self-healing polyionic liquids as electronic skin

The flexible electronic skin with self-repairing ability has recently attracted much attention because of its great potential in many fields such as artificial limbs, robots, wearable devices and medical devices. In this work, we selected imidazole-based polyionic liquid (PVI) as the conductive component and ethyl polyacrylate (PEA) as the soft segment component to study their copolymerization. Then a large volume of bis (trifluoromethylsulfonyl) imide group (TFSI) was introduced into the copolymer through ion exchange. On this basis, by changing the feed ratio of raw materials, we obtained PVI/TFSI-co-PEA with adjustable glass transition temperature and flexibility. The Tg of TF1-3 sample is only 11.75 °C, so its tensile strain is more than 140%. Importantly, we have achieved the inherent self-healing function of materials by taking the electrostatic interaction of ion pairs in the polyionic liquid (PIL) as the driving force. The copolymer can completely repair the damage at 60 °C. In addition, the flexible segment in the copolymer is very useful for improving the ionic conductivity of PIL as an ion transfer channel. At the same time, the ionic conductivity of PIL is also enhanced by the large size of anti-anions. The ionic conductivity of TF1-3 can reach 10-6S/cm. All the above features allow this self-repairing PIL to be used as a solid electrolyte in energy equipment to improve its safety and reliability, or as a strain sensor for flexible electronic skin, which is very useful in the field of artificial intelligence.