A research team consisting of NIMS, Hokkaido University, and Yamaguchi University has developed a method to easily synthesize a self-healing polymer gel made from ultrahigh molecular weight polymers (polymers with a molecular weight greater than 106 g/mol) and nonvolatile ionic liquids. This recyclable and self-healing polymer gel is compatible with the principles of the circular economy. In addition, it can potentially be used as a durable ion-conducting material for flexible IoT devices.
Self-healing polymer materials are capable of spontaneously repairing damaged areas, thereby increasing the lifetime of the material, which is expected to contribute to the circular economy. Most reports on the self-healing of polymeric materials in recent years have used a chemical approach in which functional groups capable of reversible dissociation and reformation (e.g., hydrogen bonds) have been integrated into polymer networks. However, this approach often requires precise synthetic methods and complex manufacturing processes. On the other hand, an alternative physical approach (such as the use of physical entanglement of polymer chains) to synthesize versatile polymer materials with self-healing ability has rarely been explored.
This research group recently developed a technique for the facile synthesis of UHMW gels composed of entangled UHMW polymers using ionic liquids. The mechanical properties of UHMW gels were found to be better than conventional chemically cross-linked gels. In addition, they can be recycled by heat treatment and exhibit a high capacity for self-healing at room temperature.
The use of the newly developed UHMW gel material, which is recyclable, self-healing and easy to synthesize, is expected to promote the development of a closed-loop economy. Furthermore, because this material is synthesized using non-volatile combustible ionic liquids, it can be used as a safe ionic conductive soft material in flexible electronics.