Saturday, January 28, 2012

Aerogel "Liquid Smoke" Gets Tougher and Finds Wider Use

Aspen Aerogel

Aerogel has proven to be a great insulator both on Earth, on Mars, under the oceans, and even in extreme expedition clothing, for use in both very cold and very hot environments.

Aerogels are finding wider use as insulators in the construction market, and have now reached the high end of home construction:
Over 70 years ago, scientists invented aerogel, the least dense solid known to man, and an insulator four times more efficient than fiberglass or foam. Famously, according to Dr. Peter Tsou of NASA's Jet Propulsion Laboratory, "you could take a two- or three-bedroom house, insulate it with aerogel, and you could heat the house with a candle. But eventually the house would become too hot."

Unfortunately, aerogels remained so expensive and unwieldy that only NASA used them with any regularity. However, thanks to recent production advances, aerogel insulation is now available and affordable for consumer purchase.

Even after the price drop, aerogels remain more expensive than common insulating materials. But since aerogels are more plastic than fiberglass or foam, permeable to water vapor, and flameproof, the extra cost may well be worth the investment when insulating masonry, shingles, or curved surfaces. Plus, since they're so light and efficient, aerogels reduce other building costs as well. _PopSci
Aerogel is even used by sculptors as a sculpture medium, but for it to be used to construct very large self-supporting 3D structures on its own, it needs to be toughened up somehow. Chinese and Japanese researchers have collaborated to create a hybrid aerogel using cellulose and silica, which is much tougher than regular aerogels.
The researchers at Wuhan University (China) and the University of Tokyo (Japan) have now developed a special composite aerogel from cellulose and silicon dioxide. They begin by producing a cellulose gel from an alkaline urea solution. This causes the cellulose to dissolve, and to regenerate to form a nanofibrillar gel. The cellulose gel then acts as a scaffold for the silica gel prepared by a standard sol–gel process, in which a dissolved organosilicate precursor is cross-linked, gelled, and deposited onto the cellulose nanofibers. The resulting liquid-containing composite gel is then dried with supercritical carbon dioxide to make an aerogel.

The novel composite aerogel demonstrates an interesting combination of advantageous properties: mechanical stability, flexibility, very low thermal conductivity, semitransparency, and biocompatibility _Nanowerk
A truly tough aerogel would be an amazing material for use in a wide variety of applications. Ultra lightweight, strong, flame-proof, conforming to a wide range of shapes, super-insulating, with fairly good sound insulating properties as well.

Ultralight multi-walled carbon nanotube aerogels:
This material is particularly interesting because it is composed of a dispersion of MWNTs which leave a honeycomb structure with controllable porosity. More-so, the aerogel has a large surface area and conducts electricity very well, but is a thermal insulator. This is an ideal characteristic for electronics.

Notably this is not the first aerogel made from carbon nanotubes (or CNTs for short if you’re hip to the materials crowd), nor is it the first CNT-based aerogel to exhibit amazing elastic properties. But it’s a new pathway to making CNT-based aerogels and the resulting materials are pretty cool.
Wikipedia Aerogel

Aerogel Blog

Aspen Aerogel Products and Markets

What you see above is a rapidly developing material category which is likely to expand rapidly, once it has toughened up enough to "go the distance."

A monolithic dome insulated with aerogel walls and windows should easily keep a family warm even in polar environs, for very little cost of heating. Similarly, undersea habitats, high altitude lighter-than-air ships, and outer space habitats could be kept comfortable without adding significant weight.

Al Fin seastead engineers have even suggested using toughened aerogels as insulation for pykrete seasteads, to minimise cooling expenditures for the massive free-floating island habitats. The ability to use inexpensive materials to build massive structures such as large seasteads, should make the idea practical much sooner. (Technically, the seastead engineers recommend a layer of aerogel over a layer of supercooled liquid gel directly over the pykrete. Such a "layered" approach would also provide mechanical resilience beyond the thermal super-insulation.)

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