Self-Healable UV-Triggered\nSilica–Polyurethane\nNanocomposite-Reinforced Fabric Coating: Implications for Protective\nFabrics

Developing self-healing nanocomposites\nwith robust mechanical\nproperties\nand efficient self-healing at room temperature remains a significant\nchallenge. In this study, we introduce a dual-responsive, self-healing\nnanoparticle-reinforced polyurethane nanocomposite (Si–PU NC),\nutilizing oxetane-modified silica (Si–OX) nanoparticles, hydroxyl-terminated\nsilica (Si–OH) nanoparticles, and octadecyl-functionalized\nhydrophobic silica (Si–H) nanoparticles. The Si–PU NC\nwas synthesized through a solution blending method and demonstrated\nself-healing via two mechanisms: room-temperature healing (1 h) through\nhydrogen bonding interactions and UV-triggered healing (30 min) via\noxetane group rearrangement. This dual-responsive Si–PU nanocomposite\nexhibited excellent mechanical properties with a tensile strength\nof 23.1 MPa and an elongation at break of 1260%, along with superior\nhydrophobicity by maintaining a contact angle of 130 ± 4°.\nFurther, the films healed at room temperature and under UV light showed\nefficiencies of 73.87 and 91.13%, respectively, with the retention\nof mechanical performance (RTtensile strength: 18.78 MPa,\nelongation at break: 930%; UVtensile strength: 21.25 MPa,\nelongation at break: 1165%). When applied as a protective coating\non cotton fabric, the Si–PU NC maintained its self-healing\ncapability, improving the fabric mechanical strength (tensile strength:\n57.75 MPa; elongation at break: 22.89%) while maintaining hydrophobicity\n(contact angle: 131 ± 4°). After healing, the fabric exhibited\nhealing efficiencies of 53.26% (RT) and 77.05% (UV), with recovery\nof mechanical properties (RTtensile strength: 30.76 MPa, elongation\nat break: 12.89%; UVtensile strength: 44.5 MPa, elongation\nat break: 17.44%). This nanoparticle-reinforced system delivered superior\nself-healing, mechanical durability, and hydrophobic properties, making\nit suitable for use in protective fabrics and coating applications.