But in recent years, aerogels have been commercialized and have found uses in a variety of other fields. Aerogel is an advanced material, and because of its ultra-porous structure, engineers can design not only new insulation materials for space suits and vehicles, but also filters, batteries, solar collectors, and more.

In fact, aerogel is not a material. Instead, they are a special form of solid that can be made from silica, polymers, oxides, carbon, and other materials. Although aerogels are solid, they contain so many tiny pores that they are mostly composed of air.

1. What is aerogel made of?

Aerogels are nanoporous materials, which means that although they are solid, they are filled with tiny air-filled pores called pores. These pores are key to the aerogel's unique properties. Although many materials are porous structures, such as rubber and plastic and ceramic fibers, the size of the pores of aerogel reaches the nanometer level.

In aerogel, the pores make up the majority of the material, resulting in the formation of an ultra-light solid material. The pores in the aerogel are also very small, much smaller than a human hair and too small to be seen with the naked eye. As a result, aerogel is very light and translucent, hence nicknames such as "solid cloud" and "frozen smoke".

2. What are the main characteristics of aerogel?

Aerogels are highly porous and 95% of their volume is air, which gives them a variety of unusual properties.

One of these is the fact that they are the lightest materials ever made or discovered, which makes them particularly useful in aerospace applications where weight reduction is critical.

Aerogel properties include: very low density, very low thermal conductivity, high surface area for catalytic or electrochemical reactions, and semi-transparency. The key to these unique properties is that the aerogel is not only highly porous, but the pores are also extremely small, too small to be seen by the naked eye. This means that the aerogel not only benefits from the low thermal conductivity of the air in the pores, but the air does not flow easily, which further enhances its ability to act as a thermal insulator.

3. How to make aerogel?

Despite their name, aerogels are not gels, they are highly porous solids, composed mostly of air.

Aerogel is initially a liquid, changes into a gel, and then removes the liquid. Their unique pore structure is formed by tiny particles that are bound together in the liquid phase by structures created when retained. The trick is to remove the liquid while preserving the space between the particles. These Spaces become pores in the aerogel. The most common type of aerogel is made from silica by a "sol-gel" process.

The "sol" here is made by mixing tiny solid particles with a liquid solvent. The mixture is then solidified by adding a catalyst to make the sol into a "gel" that binds the particles to each other. The liquid solvent is then removed by drying, leaving only the solid aerogel.

The processing of aerogel is essential to create its unique microstructure. Without the super-small holes left by the semi-liquid gel phase, aerogels would not have such low density or such excellent insulation.

4. What are the applications of aerogel?

Aerogel is not a specific material, but one that has been processed to make it extra porous. The most common aerogel is made from silicon dioxide (SiO2), but there are also aerogels made from graphene, iron oxide, polymers, etc.

Aerogel also comes in many forms, including board, roll felt, paint, powder, etc. Aerogel can be used in a variety of applications and can be used commercially as an insulating material. However, researchers have been developing several other technical applications for these remarkable materials.

5, heat insulation, light transmission

Aerogel's low thermal conductivity and low density make it an excellent thermal insulation material. As an added advantage, the aerogel is very light and hardly adds any weight to the structure.

Aerogel is also an excellent insulator and can be used in thin layers that require flexibility, such as space suits. Some aerogels are translucent, which means they can be used in places where traditional insulation is not available, such as Windows and solar panels. Whether used for skylights on land buildings or Windows in future space habitats, aerogel transmits light but blocks heat.

This makes them ideal for making structures easier to heat and cool, while also letting in more natural light. Aerogel is also being used as a coating for the next generation of solar collectors, allowing light to pass through but preventing heat from escaping. Aerogel's ability to block the flow of heat also makes it useful as a form of camouflage, and aerogel coatings have been tested as a way to hide infrared cameras.

6. Adsorbers and filters

The tiny pores inside aerogels give them a particularly high specific surface area, which means a lot of solid material is in contact with its surroundings. When aerogels are made of materials that attract and adhere to certain molecules or particles, they can be used as filters and adsorbents to trap substances inside pores. A familiar relative of aerogel adsorbents is silica gel, which is commonly used as a desiccant to remove moisture from the air.

Most people are familiar with silicone packets used to keep food and other items dry in air conditioning systems and other applications. After the silicone is saturated with water, it can be "charged" by heating it in an oven, which evaporates the water on its pore surface, leaving it dry and ready to be used again. The amount of water that can be absorbed increases with the increase of specific surface area. Because aerogels have a higher specific surface area than conventional silica gel, aerogels offer a greater improvement in their ability to capture water.

7. Application of advanced technology

The high specific surface area of aerogels means that they have a lot of material in contact with their environment. This allows aerogels to be used for a large number of chemical and electrochemical processes that can be improved by maximizing the contact area between the solution and the solid matrix. These include use as catalysts or catalyst substrates for various industrial chemical processes and electrodes for next-generation supercapacitors.

Because aerogel is a structure that can be made from a variety of materials, researchers are constantly developing new aerogels and new ways to use them. As more new materials are converted into aerogels, they will facilitate the development of new technologies such as new supercapacitors, antibacterial coatings, oil spill absorbent pads, bone implants, and more. Due to its unique combination of low thermal conductivity, low density, high surface area and semi-transparency, aerogel is being developed into a variety of cutting-edge material technologies.