Highly efficient self-healable and robust fluorinated polyurethane elastomer for wearable electronics

Self-healable polyurethanes (PUs) containing reversible dynamic bonds have been widely recognized and rapidly developed in recent years. Because the self-heal capability and mechanical properties of materials are mutually exclusive in nature, it is still a formidable challenge to design a highly efficient self-healable and robust PUs, especially in wearable electronics field. Herein, a series of self-healable thermosetting PU elastomer based on widely used phenolic urethane bond was prepared to achieve above requirements. In order to investigate the effect of introducing different bisphenol chain extenders into the hard segment domain on the dissociation temperature of phenolic carbamate bond, both bisphenol A (BPA) and bisphenol AF (BPAF) were used to synthesize thermosetting PU elastomers (PU-BPA and PU-BPAF). The healing efficiency of PU-BPA was 95% with a thermal treatment at 100 °C for 1 h, and its initial dissociation temperature was 90 °C. Due to the presence of trifluoromethyl (-CF3) group, the thermal self-healing efficiency of PU-BPAF was improved, which could be completely healed (100%) at the same conditions and its initial dissociation temperature was reduced to 80 °C. PU-BPAF were used to prepare a self-healable triboelectric nanogenerator (SH-TENG) to convert mechanical movements into electrical energy that can be applied to next-generation wearable devices.Their measured open circuit voltage, short circuit current, short-circuit charge quantity were 240 V, 2.20 μA, 20 nC, respectively. In addition, the PU-BPAF based SH-TENG exhibited better self-cleaning ability (83%) than that of PU-BPA elastomer, which was attributed to the introduction of trifluoromethyl reducing the surface energy of the material. Consequently, PU-BPAF showed great potentials as a self-healable and stretchable conductor to be applied to flexible electronic devices.