Effects of Triazole Functionalized SiO₂/TiO₂ Nanoparticles in Polyurethane Coating: A Study on Structural, Thermal, Dynamic Mechanical, Morphological and Electrochemical Properties in Marine Environment

Abstract

Newly synthesized functional nanoparticles, 3-amino-1, 2, 4triazole-5-thiol (ATAT)/SiO 2 À TiO 2 nanoparticles, investigated by Transmission electron microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/ EDX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis, were added to the polyurethane (PU) matrix. The produced PU-ATAT/SiO 2 À TiO 2 nanocomposite coated steel specimen was studied by Scanning electrochemical microscopy (SECM), potentiodynamic polarization and Electrochemical impedance spectroscopy (EIS) for their barrier properties against corrosion. The coating resistance (R coat ) of the PU-ATAT/SiO 2 À TiO 2 nanocomposite was found to be 2956.90 kΩ.cm 2 . It was found that the coating resistance of PU-ATAT/SiO 2 À TiO 2 nanocomposite coating was over 50 % higher than that of the PU coating. The current measured along the scratched surface of the PU-ATAT/SiO 2 À TiO 2 nanocomposite coating was found to be very less (1.65 nA). The degradation products analyzed by SEM/EDX and XRD displayed the enriched ATAT/SiO 2 À TiO 2 nanoparticles which hindered the passage of electrolytes into the interface of coating. The hydrophobic nature of the PU-ATAT/SiO 2 À TiO 2 nanocomposite coating (θ = 115.4°) was confirmed by water contact angle measurement. The least oxygen permeability was observed in the PU-ATAT/SiO 2 À TiO 2 . The improved mechanical properties were found by dynamic mechanical analysis (DMA) for the PU-ATAT/SiO 2 À TiO 2 nanocomposite coating. Therefore, the newly synthesized PU-ATAT/SiO 2 À TiO 2 nanocomposite provided an outstanding barrier and mechanical properties due to the addition of ATAT/SiO 2 À TiO 2 nanoparticles to the polyurethane, which obstructed the degradation of materials and assisted in prolonging the life of the coated steel.