Hydrophobic-Barrier Strategy for High-Silicon Polyurethane Hydrophobic Coatings with Wide Temperature Range Stability

Abstract

Silicone polyurethane coatings are widely applied in protective fields, yet fail to satisfy demands of high hydrophobicity and superior corrosion resistance due to limited copolymer silicon block content. To address these challenges, this study proposes a customized silane chain extender bridging strategy: a self-synthesized tetrahydroxysilane chain extender (KH-ADD) serves as an interfacial bridge to link high-content PDMS with the polyurethane matrix. This constructs a dense cross-linked network and surface PDMS-enriched layer structure, realizing synergistic optimization of hydrophobic-barrier properties. The optimized PU-KD-PDMS15% coating achieves a static water contact angle of 122.3° to resist liquid adhesion and penetration, an impedance modulus of 3.5 × 1010 Ω·cm2, and remarkable corrosion resistance: after 720 h of salt spray and seawater immersion, it retains ratings of 6 and 10, respectively, whereas the low-silicon coating fails completely (rating 0). It also exhibits wide-temperature adaptability (T5% more than 300 °C, Tg = −73 °C) and remarkable weatherability, with negligible surface property attenuation after prolonged UV (365 nm) and thermal (120 °C) aging. Notably, this coating significantly enhances the hydrophobicity and corrosion resistance of commercial polyester. This strategy provides a feasible molecular design approach for multifunctional polyurethane coatings with integrated hydrophobicity, corrosion resistance, wide temperature adaptability, and weatherability, offering effective solutions for extreme-environment long-acting protective coatings.