Preparation of self-healing MXene/chitosan/benzaldehyde-polyurethane flexible conductive coating for dual-mode sensing applications

Flexible conductive coatings have the potential to imbue traditional textiles with a range of functional or intelligent properties, including sensing, light emission, heat generation, etc. However, these flexible coatings are prone to damage from external forces in real-world applications. This study focuses on developing a chemically modified flexible coating with MXene as a conductive ligand, aiming to strike the characteristics of mechanical, conductive, and self-healing harmoniously. The process involves synthesizing modified 4-vinyl benzaldehyde into polyurethane (VPU), which is then cross-linked with chitosan to enhance the self-healing efficiency. The conductive ligand, MXene, was modified with tannic acid to strengthen hydrogen bonding with the VPUs. The resulting self-healing waterborne polyurethane conductive coating exhibits an impressive self-healing efficiency of 96 %, along with a high tensile strength at a break of 5.58 MPa and an elongation at a break of 340 %. It also demonstrates antimicrobial effects against Escherichia coli and Staphylococcus aureus of up to 86.8 % and 90.1 %, respectively. Importantly, this study also explores the wearable applications of flexible electronic devices. They can detect pressures up to 100 kPa in a maximum sensitivity of 0.204 kPa⁻¹ in the initial pressure range from 1 to 15 kPa. They can also monitor the pressure response of the foot in different motion states, suggesting potential integration with insoles or socks. This work offers a practical method for combining the key properties of polymer conductive coatings with the design of carbon nanomaterial-based stress-strain sensors. They are potentially applied to this approach including smart robots, e-skins, wearable health management systems, and artificial intelligence, among others.