MXene/Polyurethane Flexible Films for Wearable Pressure Sensors with High Sensitivity and Electromagnetic Shielding

The polyurethane film is becoming an excellent substitute of flexible sensing substrate due to its tunable structure, excellent toughness, and flexibility. However, there are still considerable challenges in endowing the insulating polyurethane with permanent electrical conductivity. In this study, Ti3C2 MXene with more hydroxyls was obtained by etching Ti3AlC2 MXene, and then, as a chain extender, it was introduced into the polyurethane matrix by covalent bonding; as a result, a conductive MXene-modified polyurethane film (PUM) was prepared. The FTIR, EDS, XRD, and XPS results showed that Ti3C2 MXene was successfully grafted on a polyurethane matrix by chemical binding. When the amount of Ti3C2 MXene was 20 wt %, the mechanical properties (tensile strength of 10.8 MPa) and electrical conductivity (240 S/m) of the prepared PUM20 film were the best. The test results of sensing performance showed that the PUM20 sensor displayed different output signals under different movements, and its response time was only 1.8 s, highlighting that the PUM sensor had a higher sensitivity. Additionally, the PUM sensor also represented excellent electromagnetic shielding performance (EMI SE = 26.5 dB). The self-developed flexible PUM sensor exhibits great potential application in the detection of human joint motion, electromagnetic shielding, battery separators, and energy storage. This study provides different ideas for the application of polyurethane films in sensors.