aerogel

aerogel
Courtesy NASA/JPL-Caltech · Public domain · source
Name	Aerogel
Classification	Solid, porous material
Discovered	1931
Inventors	Samuel Stephens Kistler
Density	0.001–0.5 g/cm³
Thermal conductivity	~0.013–0.025 W/m·K
Porosity	70–99.8%

aerogel Aerogel is an ultralight, highly porous solid first developed in 1931 that combines extreme low density with high surface area and low thermal conductivity. It has been studied and deployed by researchers and organizations across Massachusetts Institute of Technology, NASA, University of California, Berkeley, Lawrence Berkeley National Laboratory and companies such as Cabot Corporation and Aspen Aerogels. Its unusual properties have attracted interest from scientists affiliated with institutions like Harvard University, Stanford University, Caltech, Oak Ridge National Laboratory, and Sandia National Laboratories.

History

Samuel Stephens Kistler produced the first aerogel in 1931, displacing liquid in a gel without collapsing the solid network and drying the gel under controlled conditions. Subsequent development involved chemists and engineers at DuPont, General Electric, 3M, and academic groups such as University of Illinois Urbana–Champaign and University of Minnesota. Interest surged when agencies like NASA used silica-based aerogels for hypervelocity capture in missions including Stardust (spacecraft), with contributions from teams at Jet Propulsion Laboratory and Smithsonian Institution. Commercialization emerged through firms like Cabot Corporation and startups spun out from Massachusetts Institute of Technology and Dartmouth College research labs.

Composition and Structure

Aerogels are often based on silica, organically modified silicates, carbon, alumina, titania, or polymers; research groups at Monash University, University of Cambridge, ETH Zurich, and University of Tokyo have explored diverse chemistries. The solid framework is a nanoporous network with pore sizes typically in the mesoporous and macroporous ranges characterized by standards from organizations like International Union of Pure and Applied Chemistry and measurement labs at National Institute of Standards and Technology. Structural models used by investigators at Max Planck Society and Lawrence Livermore National Laboratory describe fractal networks, high specific surface area (often 600–1200 m²/g), and skeletal thickness on the nanometer scale.

Synthesis and Manufacturing

Traditional synthesis follows sol–gel chemistry pioneered in laboratories such as University of Oxford and University of Michigan, where a precursor (e.g., tetraethyl orthosilicate for silica aerogel) undergoes hydrolysis and condensation to form a wet gel. Drying strategies include supercritical drying with equipment modeled on systems used at Argonne National Laboratory or ambient pressure drying enabled by surface modification techniques developed at University of Minnesota and Northwestern University. Freeze casting and 3D printing approaches from teams at ETH Zurich and Massachusetts Institute of Technology expand manufacturing options. Scale-up and process control have been addressed by industrial partners such as Aspen Aerogels and research consortia involving Oak Ridge National Laboratory.

Physical and Chemical Properties

Aerogels exhibit extreme low density (approaching that of air), high porosity (up to 99.8%), low thermal conductivity exploited by Oak Ridge National Laboratory and NASA, and large internal surface areas measured by groups at Brookhaven National Laboratory and Lawrence Berkeley National Laboratory. Optical properties include high transparency for silica aerogels used by Jet Propulsion Laboratory and characteristic blue scattering studied by teams at California Institute of Technology and University of Cambridge. Mechanical behavior—brittleness, compressive strength, and elasticity—has been quantified in studies from University of Illinois Urbana–Champaign, Imperial College London, and Delft University of Technology. Chemical stability and reactivity depend on composition; carbon aerogels developed at Ecole Polytechnique and MIT show electrical conductivity exploited by researchers at IBM Research and NREL.

Applications

Aerogels have been used in thermal insulation by Boeing and Siemens, in particle capture by NASA during the Stardust (spacecraft) mission, and in environmental remediation studied by U.S. Environmental Protection Agency collaborators. Energy storage and electrode research from Argonne National Laboratory, Lawrence Berkeley National Laboratory, and Stanford University employ carbon and hybrid aerogels in batteries and supercapacitors. Acoustic and electromagnetic applications have been pursued by teams at MIT, Caltech, and Fraunhofer Society. In construction and building retrofits, companies like Aspen Aerogels and consortia including National Renewable Energy Laboratory have trialed aerogel blankets and panels. Medical and catalyst supports have been developed in labs at Harvard Medical School and ETH Zurich.

Safety and Handling

Handling guidance draws on standards used by Occupational Safety and Health Administration and testing protocols at National Institute for Occupational Safety and Health, since fine particulate from mechanical abrasion can pose inhalation hazards similar to silica dust assessed by World Health Organization and International Labour Organization research. Thermal stability, flammability, and chemical compatibility are evaluated in facilities such as Underwriters Laboratories and national labs like Sandia National Laboratories. Protective measures and material data sheets from manufacturers including Cabot Corporation and Aspen Aerogels recommend engineering controls, respiratory protection specified by NIOSH, and waste management consistent with regulations enforced by U.S. Environmental Protection Agency.

Economic and Environmental Considerations

Commercial adoption involves capital and operational costs analyzed by consultants and agencies like International Energy Agency and market studies from firms tied to BloombergNEF and McKinsey & Company. Lifecycle assessments performed by researchers at University of Cambridge, ETH Zurich, and Fraunhofer Society consider energy-intensive supercritical drying versus greener ambient drying routes developed at Northwestern University. Supply chains for precursors link to chemical producers such as Evonik Industries and BASF, while recycling and end-of-life strategies have been explored by groups at Imperial College London and Cranfield University. Policy and procurement by organizations like European Commission and U.S. Department of Energy influence deployment in buildings, aerospace, and energy sectors.

Category:Materials