Aerogels are the lightest solids ever produced. Highly porous and almost wispy in appearance, aerogels produced from such materials as silica, alumina, or zirconia can have densities as low as just three times that of air. These microporous materials have other unusual and desirable properties as well, making them candidates for a wide range of applications. Aerogels have the lowest density (- 0.03 g/m3), lowest thermal conductivity (- 3 mW/mK), lowest dielectric constant (- 1.01, with loss tangent: 0.0001 x density), lowest acoustic velocity (- 100 m/s), and lowest refractive index (- 1.03) of any known solid on earth. Due to the nano-sized (10 nm -) open pore structure produced at high uniformity, aerogels have extremely high internal surface areas (up to 2000 m2/g).
Although discovered in 1931, it was not until fairly recently that scientists could take advantage of this impressive set of qualities, because aerogels were extremely difficult and dangerous to synthesize. Now that aerogels can be readily made – John Glenn even synthesized aerogels in space – the University of Virginia Aerogel Research Laboratory has emerged as an international focal point for aerogel studies. The Aerogel Research Laboratory, located on the grounds of the University of Virginia in Charlottesville, Virginia, was established in 1996 to investigate fundamental properties as well as cutting-edge applications of aerogels. We have the capabilities to custom design aerogel materials optimized for a wide-variety of applications and are eager to team with industry.
More about Nanotech and Aerogel (Exec Assoc Dean Norris starts at 4:40)
Aerogels are produced by a chemical preparation technique known as the sol-gel process followed by either supercritical extraction or modified ambient drying method (see Figure). Silica aerogels, the most common form, are prepared as shown below. Starting with a solution of partially polymerized silica, water, alcohol, and a catalyst, condensation and polymerization initiates and continues until the solid silica matrix spans the container.
Aerogel is an extremely adaptable material. The sol-gel production process offers the ability to tailor the material properties for specific applications. By adjusting the reaction conditions, such as pressure, temperature, and stoichiometry, properties of the resulting aerogel (such as density, surface area, porosity and pore size) can be adjusted and optimized for the intended application. During the gelation process dopants can be integrated into the sol and covalently attached to the silica backbone, thus imparting functionality to the resulting product. By adjusting the viscosity of the sol, we can prepare spin-coated thin films, fibers, microspheres, or coatings.Applications include superinslulation, substrates for chemical catalysis, acoustic delay lines, sea water desalinization, subatomic particle detectors, micrometeoroid collectors, and supercapacitors. An example of a novel application is in space exploration. Aerogels were used to insulate the Mars Rover, a mission where its lightness and strength proved ideal.In the laboratory, we produce aerogels in a variety of configurations, from bulk monoliths to thin films to microspheres, in small to medium-sized batches. The Aerogel Research Laboratory is also equipped to machine or produce aerogels in a variety of shapes.
- Thin film aerogel coating for thermal and electrical insulation in MEMS and MMIC devices (see figure).
- Measurement of the thermal properties of thin film aerogels
Organometallic aerogel/xerogel materials for:
- Catalysts and catalytic supports
- Micro- and nano- patterning
- IR (infrared radiation) absorption
Organic & organic-inorganic hybrid aerogels for:
- High temperature thermal protection systems