A rapid low temperature self-healable polymeric composite for flexible electronic devices

The ability to undergo healing upon mechanical damage is a highly sought-after property for the new generation of flexible, integrable devices. The thermally reversible Diels-Alder (DA) mechanism for self-healing is promising but has been demonstrated for healing only at high temperatures (similar to 120 degrees C). However, the DA mechanism can be triggered at temperatures as low as 50 degrees C, indicating that the self-healing mechanism is limited by the thermal mobility of the polymeric chains. Herein, we show that incorporation of the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITFS) alleviates this challenge, rapidly accelerating healing, while concomitantly improving the dielectric constant and the mechanical properties of a polyurethane derivative based on the DA chemistry (PU-DA). For optimized compositions, the healing temperature reduced from 120 degrees C to 60 degrees C and the maximum strain to failure significantly increased from 17.1% to 102.1%. Owing to the ionic polarizability of EMITFS, the composite exhibited highly attractive dielectric properties with the dielectric constant being enhanced from 2.7 to 12.9. Finally, we demonstrate a highly flexible, healable and fully solution-processed electroluminescent device.