A covalently cross-linked reduced functionalized graphene oxide/polyurethane composite based on Diels-Alder chemistry and its potential application in healable flexible electronics

A self-healing polymer with excellent mechanical properties, thermal stability, and multiple repairing has attracted increasing interest. However, very few works focused on the self-healing composites and investigated their applications in flexible electronics. Herein, covalently cross-linked reduced functionalized graphene oxide/polyurethane (RFGO/PU) composites based on Diels-Alder (DA) chemistry were developed and applied in healable flexible electronics. GO sheets were modified by furfurylamine followed by reduction resulting in RFGO sheets. Then RFGO was covalently cross-linked with furfuryl-contained linear PU and bismaleimide by DA chemistry. Benefiting from the successful modification of furfuryl, the good dispersion and excellent capability of microwave-to-heat conversion of RFGO, the synthesized composites exhibited not only enhanced mechanical properties and great thermal stability but also excellent electromagnetic wave healable properties. In addition, new composites were employed as the elastic matrix and introduced into the three-dimensional fragmentized graphene foam which served as the conductive path to fabricate flexible electronics. The as-prepared flexible electronics were successfully employed as flexible conductors and strain sensors and were able to detect the biosignals of finger bending. Besides all these, these flexible electronics could be healed efficiently using microwaves in 5 minutes showing great potential in healable flexible electronics.