Synergistic effect of multiple hydrogen bond and disulfide bond on healing waterborne conductive polyurethane composite

Flexible strain sensors are entering human life at an extremely rapid rate depending on its excellent flexibility, comfort and bio-compatibility. However, they are expensive and inevitably break down in the application process. In order to increase the economic efficiency and prolong the service life, healing properties are given to the sensors. Here, waterborne polyurethanes with a physically cross-linked structure of chain entanglement and a multi-hydrogen bonding system were constructed to achieve a tensile strength of 30.85 MPa, an elongation at break of 314.6% and a healing degree of 100% at 60 °C. Further, using the film as the base material and the nano-silver wire as the conductive medium, a healing composite conductor with a double-layer structure was prepared. The square resistance was 75.9 Ω·sq−1 and 100% healing was achieved within 5 h under near-infrared ray and heated healing conditions. Applications in the detection of human motion are highlighted, providing the feasibility of flexible strain sensors in practical applications.