Development of Nano-ZnO-Modified Rosin-Based Waterborne Polyurethane Coatings for Hydrophobicity, UV Resistance, and Anticorrosion Properties

To improve the mechanical properties, eco-friendliness, and anti-corrosion properties of waterborne polyurethane (WPU) coatings, a nano-ZnO-modified rosin-based waterborne polyurethane (ZnRWPU) was synthesized via a prepolymerization method. The synthesis involved reacting silane coupling agent KH550-modified nano-ZnO (KH550@ZnO) with rosin-based acrylate glycol diol and isophorone diisocyanate (IPDI). The structure of the polyurethane was characterized by fourier transform infrared (FT-IR) spectra and X-ray powder diffractometer (XRD), ultraviolet spectra (UV–vis) for UV absorption capacity, thermogravimetry (TG) for thermal stability, water contact angle and water absorption for water resistance, and electrochemistry for corrosion resistance of the coating. The results showed that nano-ZnO could effectively improve the hydrophobicity, thermal stability, and UV protection of ZnRWPU, and the corrosion resistance of ZnRWPU in acid alkali and salt corrosion solutions were all increased compared with the RWPU without nano-ZnO. The optimal corrosion resistance was observed when the amount of nano-ZnO was 0.6 wt%. The successful integration of rosin with nano-ZnO modification offers a viable strategy for designing a new generation of high-performance, bio-based WPU coatings. Highlights Enhanced hydrophobicity and water resistance of the coating. Improved UV-blocking capability and thermal stability. Superior corrosion resistance in acidic, alkaline, and saline environments. Optimum overall performance achieved at 0.6 wt% nano-ZnO loading.