Aerogels

Part of speech: noun

Definitions

1. A highly porous and low-density material created by replacing the liquid in a gel with a gas, often used for insulation
2. A lightweight substance that maintains its form while being composed mostly of air, ideal for various industrial applications
3. A solid framework derived from a gel that has been dried, resulting in an incredibly low mass and high thermal resistance

Etymology: Aerogels are so light that a block of silica aerogel can seem to hold nothing at all, and the name was first used for something quite different from the material we know today. In the early 1920s, the term "aerogel" was coined by the British-Irish chemist Frederick G. Donnan, who applied it to coagulated aerosols, which are clouds of tiny particles in air that had gathered into a gel-like mass. The name joins "aero-", from the Greek "aēr" meaning air, with "gel", a shortened form of "gelatin" used for any jelly-like colloid. The later material came out of that older idea. A gel is a solid network holding liquid, and an aerogel is made by drying such a network so that the liquid leaves without collapsing the structure, leaving mostly air behind. Because the word was built from parts describing its make-up rather than its appearance, it stayed useful as the science moved from smoke particles to the solid, featherweight materials that now bear the name.