High-performance waterborne polyurethane driven by cation-π interactions for damage visualization and information anti-counterfeiting

Currently, eco-friendly waterborne coatings typically suffer from low strength and susceptibility to damage, particularly facing the lack of functionality. However, introducing functional moieties into coatings often results in a further reduction of mechanical properties. Therefore, achieving a trade-off between high performance and multifunctionality presents a significant challenge. Herein, we propose a strategy involving the direct incorporation of two self-synthesized fluorescent chain extenders into the main chain, constructing a non-covalent crosslinking network based on dual dynamic cation-pi interactions, thereby realizing the integration of high performance and multifunctionality in waterborne polyurethane. The as-prepared films exhibited outstanding mechanical properties (tensile strength, 74.75 +/- 6.41 MPa) and self-healing ability (healing within 12 h at 60 degrees C, healing efficiency of 83.4 %). These films also demonstrated excellent hardness, flexibility, and transparency, along with excellent adhesion. More importantly, the films were endowed with tunable fluorescence by various aromatic conjugated groups acting as cation ligands, enabling the encoding of multiple fluorescence information and demonstrating potential applications as fluorescence ink and probes for the rapid detection of Hg2+ and Fe3+. Additionally, the films enabled the visualization of the healing process, facilitating effective detection of minor cracks in self-healing materials.