Dynamic hydrophobicity and surface reconstruction mechanism of self-cleaning traffic marking coatings incorporating modified TiO2 nanoparticles

Abstract

Traffic markings are susceptible to environmental pollution and erosion during the service life, leading to sharp decline of visual guidance effectiveness. To address this issue, a self-cleaning traffic marking incorporating modified nano-TiO₂ is developed in this study. Surface grafting modification of nano-TiO₂ is achieved using hexadecyltrimethoxysilane and titanate coupling agents, respectively. Experimental studies demonstrated that the coupling agent modification significantly improve the dispersibility of nano-TiO₂, increasing the coating's water contact angle (WCA) to 125° while exhibiting excellent photocatalytic degradation capability for organic pollutants. Artificial accelerated UV aging test and long-term water resistance test demonstrate that the marking coating exhibited excellent weather resistance. Meanwhile, chemical resistance test and abrasion resistance test confirm that the coating combines chemical stability with high abrasion resistance. Collectively, these test results reveal that the coating possesses outstanding durability. Further research reveal that UV irradiation and mechanical abrasion synergistically reconstruct the micro and nano structure of coating surface, forming a dynamic hydrophobic enhancement mechanism. The WCAs after single UV irradiation or mechanical abrasion are 140° and 138°, respectively, while the combined mechanical abrasion and UV irradiation increase WCA to 160°. This phenomenon confirms that the coating possesses self-enhancing characteristics during service, continuously maintaining the visual guidance function of traffic marking by improving pollutant removal efficiency.