Characteristics

In a modern way, thanks to nanotechnology research, the aerogel is a silicon dioxide "gel" obtained through the "sol-gel" chemical technique and then dried in supercritical conditions. These processes give rise to a three-dimensional amorphous solid matrix made of SiO² particles with average diameter of 10 nm and open nanopores in the range from 1 to 100nm (a nanometre is a millionth of a millimetre).
The obtained structure, being extremely porous, is what gives rise to the exceptional lightness (95-99% air, or other gas, in volume) and insulation performance typical of the aerogel: this material is the lightest solid ever conceived by weighing approximately 3 times the air.

Indeed, aerogels exhibit properties and behaviours closer to those of a gas rather than to those of a solid. They have among the lowest internal sound propagation speed (100 m/s) of any known solid. The thermal conductivity is typically about 0.013 W/m°K at atmospheric pressure and up to 0.004 W / m ° K at 0.05 atm.
The mechanical properties can, only in some respects, be likened to the glass; the aerogel is therefore extremely durable but, at the same time, extremely fragile too: it can usually hold a load up to 1000 times its weight and sometimes even more, but if it’s handled roughly or bent, it will snap just like glass.