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Aerogel - lightest, most expensive stuff in the World

Lab advances the art and science of aerogels

Los Alamos National Laboratory Newsletter Week of Sept. 13, 2004 Vol. 5, No. 19

Lab advances the art and science of aerogels


by Todd Hanson

Scientists working at the Laboratory have recently
demonstrated a novel method for chemically modifying
and enhancing silica-based aerogels without
sacrificing the aerogels’ unique properties. Aerogels are
low-density, transparent materials used in a wide range of
applications, including thermal insulation, porous separation
media, inertial confinement fusion experiments and
cometary dust capture agents.
Made of silica, one of Earth’s most abundant materials,
aerogels are as much as 99 percent air, giving them not
only the highest thermal insulation value and highest surface
area, but also the lowest acoustic conductivity and
density of all known solid materials. The aerogels’
extraordinary thermal insulation ability makes them
capable of withstanding temperatures in excess of a
thousand degrees Fahrenheit. Because they are composed
mostly of air, there is little solid content
available for maintaining the structural integrity of
the aerogel, making them brittle.
In research reported at the 228th national meeting
of the American Chemical Society, Laboratory scientist
Kimberly DeFriend of Polymers and Coatings (MST-7)
described a process for modifying silica aerogels with silicon
and transition metal compounds using chemical vapor
techniques to create a silicon multilayer or a mixed-metal
oxide that enhance the current physical properties of aerogels
for more demanding applications. With the addition of a
silicon monolayer, an aerogel’s strength can be
increased four-fold.
Aerogels are synthesized at Los Alamos using solgel
processing and super-critically dried with either
carbon dioxide or a solvent. This sol-gel processing
method allows the gel to be formed in the shape of
its mold, making it possible to create a variety of
shapes. The introduction of silicon multilayers or
transition metal compounds allows the aerogels to
retain their most valuable porosity and density
characteristics while enhancing weaker characteristics
like mechanical strength.
Los Alamos recently has begun to expand and
advance its ability to synthesize and manufacture the
aerogels. This improved capability will allow
Laboratory scientists to not only more closely study
and improve on the quality of the aerogels, but also
help to better meet the Laboratory’s inertial confinement
fusion and high-energy-density physics aerogel
target needs.
In addition to DeFriend, the Los Alamos aerogel team includes Douglas Loy, Arthur Nobile Jr., Kenneth Salazar, James Small, Jonathan Stoddard and
Kennard Wilson Jr., all of MST-7.