As our planet faces the increasing threat of climate change, the impact of longer and more intense wildfire seasons cannot be overstated. The devastating effects of these catastrophic wildfires are felt in the destruction of homes and infrastructure, the loss of lives and livelihoods, and the damage to our wildland resources and economy. It is evident that we require innovative solutions urgently.
Researchers at Stanford have developed a water-enhancing gel with the potential to be a game-changer in wildfire protection. This advanced gel demonstrates exceptional longevity and effectiveness, far surpassing existing commercial gels.
This promising breakthrough holds the key to safeguarding homes and critical infrastructure from the ravages of wildfires, offering hope in the face of these mounting challenges.
“Under typical wildfire conditions, current water-enhancing gels dry out in 45 minutes,” said Eric Appel, associate professor of materials science and engineering in the School of Engineering, who is senior author of the paper. “We’ve developed a gel that would have a broader application window – you can spray it further in advance of the fire and still get the benefit of the protection – and it will work better when the fire comes.”
Water-enhancing gels are an innovative solution for fire protection, utilizing super-absorbent polymers to create a gelatinous shield when mixed with water and sprayed on a building. However, traditional gels face challenges in extremely dry conditions typical of wildfire environments, as the water locked in the gel evaporates rapidly.
In response to this issue, researchers at Appel have developed a remarkable gel that goes beyond just water protection. By incorporating silica particles and a cellulose-based polymer, this advanced gel is designed to remain resilient when exposed to high temperatures, providing a robust and long-lasting defense against wildfires.
“We have discovered a unique phenomenon where a soft, squishy hydrogel seamlessly transitions into a robust aerogel shield under heat, offering enhanced and long-lasting wildfire protection. This environmentally conscious breakthrough surpasses current commercial solutions, offering a superior and scalable defense against wildfires,” said the lead author of the study, Changxin “Lyla” Dong.
“When the water boils off, and all of the cellulose burns off, we’re left with the silica particles assembled into a foam,” Appel said. “That foam is highly insulative and ends up scattering all of the heat, completely protecting the substrate underneath it.”
The innovative silica aerogel creates a solid, porous structure that serves as an exceptional insulator. Its application in space technology is due to its incredibly lightweight nature and its ability to block most forms of heat transfer.
In their experiments, the researchers tested various formulations of the new gel by applying them to plywood pieces and subjecting them to direct flames from a high-temperature gas hand torch, exceeding the intensity of a wildfire. The most successful formulation provided protection for over 7 minutes before any charring occurred. A commercially available water-enhancing gel offered less than 90 seconds of protection under the same conditions.
“Traditional gels don’t work once they dry out,” Appel said. “Our materials form this silica aerogel when exposed to fire that continues to protect the treated substrates after all the water has evaporated. These materials can be easily washed away once the fire is gone.”
The latest gel technology represents a significant advancement in wildfire prevention. Building on Appel’s previous breakthroughs, these gels have been specifically designed to hold fire retardants on vegetation for extended periods, effectively reducing the risk of ignition in wildfire-prone areas.
“We’ve been working with this platform for years now,” Appel said. “This new development was somewhat serendipitous – we were wondering how these gels would behave on their own, so we just smushed some on a piece of wood and exposed it to flames from a torch we had laying around the lab. What we observed was this super cool outcome where the gels puffed up into an aerogel foam.”
Following the initial success, extensive engineering efforts have resulted in a stable, easily sprayable formulation that adheres to various surfaces. What’s more, these gels are composed of nontoxic components already approved for use by the U.S. Forest Service and have been shown to degrade easily in soil, making them environmentally friendly.
“They’re safe for both people and the environment,” Appel said. “There may need to be additional optimization, but my hope is that we can do pilot-scale application and evaluation of these gels so we can use them to help protect critical infrastructure when a fire comes through.”
Journal reference:
- Changxin Dong, Andrea I. d’Aquino, Samya Sen, Ian A. Hall, Anthony C. Yu, Gabriel B. Crane, Jesse D. Acosta, Eric A. Appel. Water-Enhancing Gels Exhibiting Heat-Activated Formation of Silica Aerogels for Protection of Critical Infrastructure During Catastrophic Wildfire. Advanced Materials, 2024; DOI: 10.1002/adma.202407375