Multifunctional waterborne polyurethane-cellulose nanofiber composite: Realizing ultrarobust, photoluminescence and swift self-healing via multi-dynamic bonding

The development of environmentally friendly waterborne polyurethane (WPU) elastomers can significantly reduce reliance on organic solvents, which is crucial for environmental protection. However, the manufacturing of WPU elastomers with high strength and self-healing properties has proven to be extremely challenging. Hence, a rapid self-healing supramolecular material featuring high strength was explored by synergistically combining flexible disulfide and urea bonds into water-borne polyurethane (WPU). Simultaneously, combining cellulose nanofibres (CNF) rich in hydroxyl groups with the WPU matrix not only enables a dynamic network composed of strong hydrogen bonds but also forms a strain-induced reversible network under the special nano-confinement effect. Surprisingly, the obtained nanocomposite films showed outstanding mechanical properties, with extremely high tensile strength (54.4 MPa), elongation at break (896.1 %), and toughness (255.6 MJ/m −3 (−|−)). After incorporating CNF, the nanocomposite elastomer exhibited the desired self-healing efficiency (92.7 %). Furthermore, the prepared nanocomposite elastomer emits blue fluorescence under 365 nm ultraviolet irradiation, which can be used for microcrack detection in equipment. In addition, we verified the broad application prospects of the nanocomposite elastomers in clothing anti-counterfeiting. Our study provides new insights into the development of luminescent materials with rapid self-healing abilities and high strength.