Self-Healable UV-Triggered Silica–Polyurethane Nanocomposite-Reinforced Fabric Coating: Implications for Protective Fabrics

Developing self-healing nanocomposites with robust mechanical properties and efficient self-healing at room temperature remains a significant challenge. In this study, we introduce a dual-responsive, self-healing nanoparticle-reinforced polyurethane nanocomposite (Si–PU NC), utilizing oxetane-modified silica (Si–OX) nanoparticles, hydroxyl-terminated silica (Si–OH) nanoparticles, and octadecyl-functionalized hydrophobic silica (Si–H) nanoparticles. The Si–PU NC was synthesized through a solution blending method and demonstrated self-healing via two mechanisms: room-temperature healing (1 h) through hydrogen bonding interactions and UV-triggered healing (30 min) via oxetane group rearrangement. This dual-responsive Si–PU nanocomposite exhibited excellent mechanical properties with a tensile strength of 23.1 MPa and an elongation at break of 1260%, along with superior hydrophobicity by maintaining a contact angle of 130 ± 4°. Further, the films healed at room temperature and under UV light showed efficiencies of 73.87 and 91.13%, respectively, with the retention of mechanical performance (RT─tensile strength: 18.78 MPa, elongation at break: 930%; UV─tensile strength: 21.25 MPa, elongation at break: 1165%). When applied as a protective coating on cotton fabric, the Si–PU NC maintained its self-healing capability, improving the fabric mechanical strength (tensile strength: 57.75 MPa; elongation at break: 22.89%) while maintaining hydrophobicity (contact angle: 131 ± 4°). After healing, the fabric exhibited healing efficiencies of 53.26% (RT) and 77.05% (UV), with recovery of mechanical properties (RT─tensile strength: 30.76 MPa, elongation at break: 12.89%; UV─tensile strength: 44.5 MPa, elongation at break: 17.44%). This nanoparticle-reinforced system delivered superior self-healing, mechanical durability, and hydrophobic properties, making it suitable for use in protective fabrics and coating applications.