In the sweltering summer heat, finding relief outdoors can be a challenge for everyone, from athletes to beachgoers. But what if there was a fabric that could actually cool you down? Researchers have developed a groundbreaking chalk-based coating that can lower the temperature underneath treated fabric by up to 8 degrees Fahrenheit.
Evan D. Patamia, a graduate student at the University of Massachusetts Amherst, will unveil these exciting findings at the upcoming fall meeting of the American Chemical Society (ACS). This innovative solution could revolutionize the way we stay cool in the heat, offering a simple and effective way to beat the heat.
“If you walk out into the sunlight, you will get increasingly hot because your body and clothing are absorbing ultraviolet (UV) and near-infrared (near-IR) light from the sun,” says Trisha L. Andrew, a chemist and materials scientist working with Patamia. “And as long as you’re alive, your body is generating heat, which can be thought of as light, too.”
To enhance outdoor comfort, scientists have been working on advanced textiles that deflect the sun’s rays and expel natural body heat—a process known as radiative cooling. Some materials utilize light-refracting synthetic particles like titanium dioxide or aluminum oxide embedded into spun fibers. Others employ organic polymers, such as polyvinylidene difluoride, which necessitate the use of PFAS, known as forever chemicals, in their production processes to create light-reflective textiles.
However, scaling the manufacturing of these materials for commercial use isn’t sustainable, as Andrew noted. In response, she challenged research team members Patamia and Megan K. Yee with the question, “Can we develop a textile coating that achieves the same outcomes using natural or environmentally friendly materials?”
The innovative technique developed by Andrew and his team revolutionizes the application of durable polymer coatings on fabric using chemical vapor deposition (CVD). This method simplifies the process by combining synthesis and deposition into a single step, resulting in a thin polymer layer grafted onto commercial textiles with minimal environmental impact.
Patamia and Yee’s work is equally groundbreaking as they integrate calcium carbonate and bio-compatible barium sulfate onto the polymer applied by CVD. These additives, inspired by historical construction materials, possess light-reflecting properties, offering potential benefits for a wide range of applications.
By treating small squares of fabric with a 5-micrometer-thick poly(2-hydroxyethyl acrylate) layer and repeatedly dipping them into solutions containing calcium or barium ions and solutions containing carbonate or sulfate ions, the researchers were able to create larger, more uniform crystals and give the fabric a chalky, matte finish. According to Patamia, by adjusting the number of dipping cycles, they can precisely control the particle size distribution (ranging from 1 to 10 micrometers in diameter) to effectively reflect both UV and near-IR light.
To test the cooling capabilities of the treated fabric, the researchers conducted outdoor experiments on a hot, sunny day with temperatures exceeding 90°F. The results were impressive, with air temperatures underneath the treated fabric registering a remarkable 8°F cooler than the surrounding ambient temperature in the middle of the afternoon.
Furthermore, the treated fabric outperformed untreated fabric by a staggering 15°F, significantly cooling the air underneath it. Such findings emphasize the potential applications of this innovative fabric technology in mitigating heat and enhancing comfort in various environments.
“We see a true cooling effect,” says Patamia. “What is underneath the sample feels colder than standing in the shade.”
Yee’s comprehensive evaluation of the mineral-polymer coating revealed some exciting findings. In a simulated washing machine environment, the coating proved resilient against friction and impact from laundry detergent while retaining its cooling properties. Andrew also shared his ambitious plans to scale the CVD process for bolts of fabric, marking a significant step towards pilot-scale production of these innovative innovations.
“What makes our technique unique is that we can do this on nearly any commercially available fabric and turn it into something that can keep people cool,” concludes Patamia. “Without any power input, we’re able to reduce how hot a person feels, which could be a valuable resource where people are struggling to stay cool in extremely hot environments.”
