Highly Stretchable Elastomer May Be Candidate For Artificial Muscles, Stanford University Study

Researchers from Stanford University developed a new silicone rubber elastomer, based on a poly(dimethylsiloxane) (PDMS)-derivative. The material can be stretched to 45 times its original length, a characteristic that the team attributed to the constant breaking and reforming of metal-ligand coordination bonds throughout stretching. The material can recover to its original length in one hour, with almost full recovery of its original stress-strain behaviour. The team cut the material in two, and then rejoined the ends. After 48 hours at room temperature, the material exhibited 90% healing efficiency. Furthermore, this healing ability was unaffected by surface ageing – that is, if the cut ends were left apart and exposed to air for 24 hours and then rejoined, the material saw no difference in healing efficiency compared to when the cut ends were immediately rejoined. This is in contrast with materials that rely on hydrogen bonding, where immediate re-contact is necessary for efficient healing. These characteristics are impressive, and appear to address two major issues of metal-ligand self-healing to heal strongly without an external stimulus.