A self-healing sustainable halloysite nanocomposite polyurethane coating with ultrastrong mechanical properties based on reversible intermolecular interactions

Endowing sustainable polyurethane (PU) materials with ultrastrong mechanical properties and highly efficient self-healing performance simultaneously is extremely challenging and of great significance to dramatically extend the service life of metal materials. In this work, 4,4′-dithiodianiline (DTDA) and bio-based 2,5-Tetrahydrofurandimethanol (THFDM) were used as chain extenders to introduce hierarchical hydrogen bonds and aromatic disulfide bonds into the PU matrix, after which rich interfacial hydrogen bonds were obtained by incorporating environment-friendly polydopamine-modified halloysite nanotube (PDA@HNT) into the PU matrix. The developing PU nanocomposite exhibits record toughness (774.4 MJ m−3), outstanding tensile strength (68.3 MPa), and exceptional elongation at break (2882.7 %), as well as distinguished self-healing performance (85.4 % at 35 °C for 24 h; 95.9 % at 80 °C for 15 min). Thanks to the shielding effect of PDA@HNT fillers, the PU nanocomposite also possesses good corrosion resistance proved by its high impedance value at 0.01 Hz of 2.23 × 108 Ω cm2 after immersing in 3.5 wt% NaCl solution for 30 days. This work provides constructive guidance to create an ultra-robust self-healing sustainable PU nanocomposite with long-term corrosion resistance.