Synergistic enhancement of the robustness of multifunctional polyurethane via an ionic noncovalent cross-linking network and aromatic disulfides

The preparation of functional polyurethane materials with high strength, toughness, and excellent self-healing ability is currently challenging. In this study, a multifunctional bi-dynamic supramolecular crosslinked network PU elastomer was successfully prepared by introducing ionic bonds and aromatic disulfide bonds into a PU matrix. The resulting ionic PU elastomers exhibited impressive mechanical properties, including high tensile strength (39.9 ± 4.4 MPa) and excellent elongation at break (1930 ± 345 %). They also demonstrated efficient self-healing capability (94.4 %), recyclability and processability. The distribution of hydrophilic ion bonds within the polymer networks enabled the elastomers to possess water-induced shape memory and antibacterial activity. Additionally, the hydrophilicity of the elastomers provided a self-cleaning ability when used as a coating material. The covalent bonding of the cations with the PU matrix prevented the leaching of bactericidal substances, ensuring good biocompatibility of the ionic PU. Furthermore, a double-layered self-healing composite flexible sensor was developed using the ionic PU as the substrate and carboxylated carbon nanotubes (CNTs-COOH) as the conductive medium to detect human motion. These multifunctional ionic PU elastomers offer great potential for the design and preparation of robust materials with self-healing ability for various applications across multiple fields.