Anti-graffiti coatings

 
The growing incidence of vandalism is damaging the appearance of public and private heritage sites. Addressing this issue is not only expensive but often requires the use of chemicals that can be harmful to the environment. To counter these effects, protective coatings have been developed with hydrophobic properties to repel water-based graffiti paints. Additionally, these coatings are designed to be semi-permanent, offering long-term durability and the option for reapplication when needed. Micro- and nanostructures have been shown to significantly enhance the hydrophobic properties of surfaces, thereby improving the effectiveness of anti-graffiti coatings. These structures work by mimicking natural surfaces, such as lotus leaves, which exhibit extreme water repellence due to their intricate surface texture. By creating a rough, uneven surface at the microscopic or nanoscopic level, water and other liquid-based substances, like graffiti paints, are less able to adhere, resulting in a self-cleaning effect. In this work, SiO2 nanoparticles were synthesized using the sol-gel process. Both SiO2 and commercially available alumina were functionalized through various methods, employing different modifiers such as hexadecyltrimethoxysilane (HDTMS) to enhance their hydrophobic properties. These functionalized nanoparticles were then incorporated into a polymeric solution and applied by brush onto various substrates. The coatings aimed to improve resistance to graffiti, along with providing a durable protective layer.