Because current water-enhancing gels tend to dry out quickly, often within 45 minutes under standard wildfire conditions, thereby leaving them ineffective at critical moments, the team developed a gel that can be sprayed in advance of a fire and still offer protection.

Source: Andrea d'Aquino

Stanford’s longer-lasting gel is composed of a cellulose-based polymer combined with silica particles. When introduced to the heat of a wildfire, the water in the gel will evaporate and the cellulose will burn away, leaving behind a silica-based aerogel with what the researchers suggest are excellent insulation properties.

The team explained: “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.”

Essentially, the transition from hydrogel to aerogel is what makes the material effective. This is because once the water boils off and the cellulose components burn off, the silica particles that remain assemble into a foam-like structure that functions as a thermal insulator that scatters all of the heat, thus protecting the substrate beneath it.

When applied to plywood in the lab and exposed to direct flames from a gas hand torch, which burns at much higher temperatures than typical wildfires, the new gel offered protection for more than seven minutes before the plywood began to char.

An article detailing the gel, “Water-Enhancing Gels Exhibiting Heat-Activated Formation of Silica Aerogels for Protection of Critical Infrastructure During Catastrophic Wildfire,” appears in the journal Advanced Materials.