What Is Aerogel

Aerogel is a kind of nano porous solid material formed by the sol gel method, in which the liquid phase in the gel is replaced by gas by a certain drying method [1]. Such as gelatin, arabic gum, silicone, hair, nails, etc. Aerogel also has the properties of gel, that is, expansion, thixotropy and desizing.
Aerogel is the smallest solid in the world, and one of the ten emerging technologies in the chemical field in 2022.
Aerogel is a kind of solid material form, which has the smallest density in the world. The density is 3 kilograms per cubic meter. The common aerogel is silicon aerogel gel, which was first made by American scientist Kistler in 1931 for gambling with his friends. There are many kinds of aerogels, including silicon, carbon, sulfur, metal oxide, metal and so on. Aerogel is a compound word. Here aero is an adjective, meaning "in the air". Gel is obviously gel. It literally means gel of air. The gel of any substance can be called aerogel as long as it can be dried to remove the internal solvent and keep its shape basically unchanged, and the product has high porosity and low density.
Because the density is extremely low, the lightest aerogel is only 0.16 mg/cm3, slightly lower than the air density, so it is also called "frozen smoke" or "blue smoke". Due to the extremely small particles inside (at the nanometer level), visible light scatters less when passing through it (Rayleigh scattering), just like sunlight passing through air. Therefore, it also appears blue like the sky (if nothing else is mixed in), and slightly red when viewed in front of light. The sky is blue, while the evening sky is red. Since more than 80% of the aerogel is air, it has a very good heat insulation effect. An inch thick aerogel is equivalent to 20 to 30 pieces of ordinary glass. Even if the aerogel is placed between the rose and the flame, the rose will not be damaged at all. Aerogel also has a variety of uses in space exploration, including the Russian "Peace" space station and the American "Mars Pathfinder" probes. Aerogels are also used as detectors of the Cherenkov effect in particle physics experiments. A particle discriminator called Aerogel Cherenkov Counter (ACC) in the Belle experimental detector of B meson factory, a high-energy accelerator research institution, is a recent application example. The aerogel used in this detector has the characteristics of low refractive index between liquid and gas, as well as high transmittance and solid state, which is superior to the traditional method of using cryogenic liquid or high-pressure air. Meanwhile, its lightweight nature is also one of its advantages.
This new material has a density of only 3.55 kilograms per cubic meter, which is only 2.75 times the density of air; The density of dry pine wood (500 kilograms per cubic meter) is 140 times that of it. This substance looks like solidified smoke, but its composition is similar to glass. Due to its extremely low density, it is very suitable for aerospace applications. NASA Jet Propulsion Laboratory, a new aerogel developed by Dr. Jones, is mainly composed of pure silica. In the production process, the liquid silicon compound is first mixed with the liquid solvent that can evaporate quickly to form gel, and then the gel is dried in an instrument similar to a pressurized digester, and after heating and depressurization, a porous sponge structure is formed. The proportion of air in the final aerogel obtained by Dr. Jones accounted for 99.8%.
Aerogel is sometimes called "solid smoke" or "frozen smoke" because of its translucent color and ultra light weight. This new material may seem fragile, but it is actually very sturdy and durable, capable of withstanding temperatures up to 1400 degrees Celsius. These characteristics of aerogels have many applications in space exploration. Aerogel materials are used on the Russian "Peace" space station and the American "Mars Pathfinder" spacecraft.