Coating System That Extends the Lifespan of Building Surfaces

Coating System Extends Building Surface Lifespan Researchers at Bowling Green State University's Photochemical Sciences Center have developed a coating system that shows promise in preserving historic monuments and many similar structures. The work was published in Coatings journal. A team at BGSU consisting of Dr. Joe Furgal, assistant professor of chemistry, doctoral student Cory Sims, and postdoctoral researcher Dr. Chamika Lenora used three different chemical methods to develop a hybrid organo-silicon coating system capable of extending the lifespan of numerous surfaces exposed to high levels of erosion, including national monuments, historic structures, sculptures, gravestones and buildings. Supported by the National Park Service, U.S. Department of the Interior, and the National Center for Preservation Technology and Training, the research team sought to reduce environmental damage while developing a coating that cures rapidly, offers long-term durability and can be applied in multiple ways. The results obtained so far have been both encouraging and rewarding. Sims, who presented the research at the Northeast Ohio Polymer Initiative (PiNO) conference held at Case Western University, won the PPG Choice Poster Award. Initially, Furgal was developing a coating system to make boat surfaces more hydrophobic or water-repellent, but saw that the park service was seeking to ensure materials were resistant to erosion. "I found this coating system and actually designed it for boats, but at that time it was just an idea and we hadn't done anything yet," Furgal said. "When I saw the national park grant, I thought, 'Could we use this type of coating for monument preservation?'" After a year of testing, BGSU researchers discovered their system was effective on a wide variety of surfaces. "You can use it on stone, steel, iron, glass, concrete, brick, wood – pretty much everything except fabrics," Sims said. "Ideally, it can reduce erosion and help with graffiti because after the coating is applied, you can wipe off Sharpie or spray paint with just a little elbow grease." The BGSU team used three different chemical methods (UV-initiated thiol-ene reaction, amine/epoxy reaction, and alkoxysilane sol-gel curing) to reduce undesirable qualities while achieving desired properties for each method. Acrylics require long curing times, which can make them difficult to use on surfaces already exposed to the elements. Fluoropolymers like Teflon raise environmental concerns and cannot be used on all surfaces, while some epoxies tend to oxidize and discolor as they erode. Additionally, the team faced challenges in how to test the coating, requiring them to use weathering chambers that simulate ultraviolet aging to test various extreme climate conditions, so they improvised. "Initially we had to build our own weathering systems, but eventually we decided it wasn't possible to test indoors," Furgal said. "Instead, we decided to go up on the building's roof and expose them to the real world. We had a year of real-world testing before publishing anything." By moving coated surfaces, including stone and glass, to the roof of the Physics Science Laboratory Building on campus, they exposed samples to one of their geographic advantages: North Ohio air permits many types of erosion. "Fortunately, Ohio has everything: plenty of rain, plenty of ice, plenty of snow, extreme heat, some extreme cold," Sims said. "We don't have forest fires or sandstorm-type conditions, but they've seen pretty much everything." During testing, the tri-system coating samples showed improved hydrophobicity on many surfaces including glass, steel, wood, marble, granite, brick and neoprene, and less early reactivity to multiple erosion types, with all surfaces benefiting from the coating. Wood remains the primary structural material for many historic buildings that can be difficult to maintain because it is both porous and combustible. However, sampling on brick showed the surface absorbs the coating, making it more resistant to water damage. Additionally, flame-resistance tests have been promising. During direct flame exposure, treated wood maintained its shape and self-extinguished 11 seconds after flames were extinguished; this was 90 percent faster than untreated wood, indicating a possible application for wooden structures in fire-prone areas. Coated stone surfaces observed throughout the year showed long-term stability in outdoor environments with temperatures ranging from below zero to above 100 degrees Fahrenheit, making it ideal for stone monuments such as those in cemeteries. While the research set out to solve a problem for the National Park Service, it has also shown the coating system could have broader applications. Researchers are currently in the patent application process and working on both licensing and startup company possibilities for commercialization. "We saw it worked," Sims said. "If you had asked me a year ago, I would have said I'd be happy if it just worked on stone, but we've seen it work on far more than that."   Academic Reference: Cory B. Sims et al, Hybrid Tri-Cure Organo-Silicon Coatings for Monument Preservation, Coatings (2022). DOI: 10.3390/coatings12081098 Source