(Image: Craig Mackie)
Almost as light as air, aerogels are a heavyweight solution for everything from heat-bleeding windows to carbon emissions
In the 1930s, a US chemist called Samuel Kistler made the world’s lightest solid. His trick was to gently remove the liquid from a gel of silica, leaving a fine skeleton riddled with nanoscale holes. Made up of 99 per cent air, it looked like frozen smoke. Kistler named it “aerogel”.
Aerogel was regarded as a mere curiosity for decades: it was extremely brittle, limiting its potential uses. Over the past decade, though, that has begun to change. Chemists have reinforced aerogel with glass fibres, and impregnated it with thin polymer chains to make it more flexible. An all-polymer aerogel devised by a team at NASA’s Glenn Research Center in Cleveland, Ohio, is claimed to be as flexible as rubber, while being 500 times stronger than Kistler’s original.
In parallel, there’s been an explosion of applications. On the home front, all that trapped air makes aerogels insulating superstars: a 1-centimetre thickness is enough to replace 5 centimetres of high-performance foam insulation. Translucent eco-windows incorporating aerogels can keep buildings warmer than conventional double glazing with a fraction of the weight. High-end winter sports clothing increasingly incorporates the stuff, and a version of Google’s Nexus 7 tablet computer features a plastic aerogel casing that is half the weight of a conventional plastic case.
But a new type of aerogel holds perhaps the most revolutionary promise. Metal “nanofoams” have a framework of metal atoms rather than silica or polymers. A team at Los Alamos National…
