Aerogels are among the lightest materials in the world, and are highly porous with strong absorption capacity and low thermal conductivity. These unique properties make aerogels highly suitable for applications in areas including oil spill cleaning, personal care products such as diapers, and for heat and sound insulation.
While aerogels were first created in the 1930s, this advanced material has not been widely adopted by industries due to its high production cost. Leading aerogel scientists around the world are therefore actively looking at ways to improve the manufacturing and consumption of different types of aerogels.
A fast, inexpensive, green method was developed to convert cotton-based fabric waste, such as unwanted clothing, into highly compressible and ultralight cotton aerogels. The novel cotton aerogels can be easily compressed, and can also very quickly recover up to 97 percent of their original size when placed in water.
The cotton aerogels can be fabricated within eight hours — about 20 times faster than current commercial fabrication processes. They are also stronger, making them more suitable for mass production.
Hemorrhaging caused by gunshot wounds or other deeply penetrating wounds can often be life-threatening. Existing hemorrhage control devices comprise a syringe filled with small capsules of cellulose-based sponge, coated with chitosan, a natural agent derived from the shells of shrimp and other crustaceans that promotes blood clotting. The syringe is inserted into the wound to release the capsule, which expands and applies pressure on the wound to stop the blood flow; however, the expansion and absorption rates of cellulose-based sponges are still relatively slow.
To address these limitations, pellets of the cotton-based aerogel were created that are more effective than cellulose-based sponges for treatment of deep hemorrhagic wounds. These pellets can be easily integrated into a clinical syringe to be used as a hemorrhage control device. The cotton aerogel pellets also are biocompatible, so they can be administered safely for treatment.
Each cotton aerogel pellet can expand to 16 times its size in 4.5 seconds, which is significantly larger and more than 3 times faster than existing cellulose-based sponges — while retaining their structural integrity. The unique morphology of the cotton aerogels allows for a larger absorption capacity, while the compressible nature enables the material to expand faster to exert pressure on the wound.
Soldiers regularly embark on vigorous physical activities in hot and humid conditions. The military canteen is an essential item in a soldier’s survival kit, carrying fluid for rehydration and mitigation of heat injuries. A military canteen can typically hold one liter of water and maintain its cool temperature for about 30 minutes in a tropical climate.
A lightweight thermal jacket made of the cotton aerogel layer embedded with commonly used fabrics was devised to maintain the temperature of ice slurry — crushed ice and liquid water — at 0.1 to 1.0 °C for more than four hours. The thermal jacket, which weighs about 200 grams, offers better heat insulation performance compared to commercial insulated water bottles, and is highly comparable to that of vacuum flasks.