Aerogel is a remarkable synthetic material often described as “solid smoke” or “frozen smoke” due to its translucent appearance. It is a solid with the lowest density ever created, composed of a porous network where the liquid component of a gel has been replaced by gas. This process results in a substance that can be over 99.8% air by volume while retaining its structural integrity. Aerogel’s unique physical characteristics make it a highly sought-after material for specialized applications.
What Makes Aerogel Unique
The distinctive feature of aerogel is its high porosity, which is responsible for its performance as a thermal insulator. The material’s structure is a nanoscale network of interconnected solid particles, with air filling the vast majority of the space between them. For instance, silica aerogel can have a density as low as 0.0011 grams per cubic centimeter, making it only slightly denser than air itself.
This porous structure severely limits the three mechanisms of heat transfer: conduction, convection, and radiation. The solid silica component is a poor conductor, and the nanometer-sized pores trap air molecules, preventing air movement and blocking convection. This results in a thermal conductivity value as low as 0.012 Watts per meter-Kelvin, giving it superior insulating capacity compared to traditional materials like fiberglass. Although the initial form is a brittle block, commercial products are often sold as flexible blankets or rolls, embedding the aerogel particles within a fiber matrix for durability and ease of handling.
Where to Purchase Aerogel Products
Acquiring aerogel depends on whether the goal is a small sample for demonstration or a large volume for a practical application. For individual enthusiasts, small blocks, discs, or cylinders of classic silica aerogel are available from specialty online retailers that cater to the hobbyist and collector market. These samples are ideal for educational purposes and demonstrations of the material’s unique properties.
For those seeking to use the material for its insulating properties, industrial-grade aerogel is typically found in the form of flexible blankets or pre-formed panels. These products are sold by specialized manufacturers and industrial suppliers for use in construction, oil and gas pipelines, and aerospace applications. Consumers can source these rolls through dedicated insulation distributors or large scientific supply houses. When purchasing, it is important to distinguish between hydrophobic (water-repelling) and hydrophilic (water-absorbing) formulations, as the hydrophobic versions are necessary for almost all practical, long-term insulation uses.
Understanding the Cost of Aerogel
Aerogel is significantly more expensive than conventional insulation materials, a cost driven primarily by its complex manufacturing process. The most expensive step is supercritical drying, which is necessary to remove the liquid from the initial gel without causing the structure to collapse from capillary forces. This process requires specialized, high-pressure equipment and often involves high energy consumption to manage the temperature and pressure of carbon dioxide or other solvents.
The chemical precursors used to create the gel, such as tetramethyl orthosilicate (TMOS), are costly and require careful handling. Industrial aerogel blankets, which incorporate the aerogel into a fiber matrix, can cost many times more per square foot than standard foam or fiberglass insulation. While a small cube for a demonstration might cost around $40 to $60, the price for a large industrial roll can enter the hundreds or thousands of dollars. However, the material’s superior insulating performance allows for much thinner layers to achieve the same R-value, which can lead to long-term energy savings that offset the initial high purchase price.
Creating Aerogel Samples at Home
It is possible to create small aerogel samples, though the process is challenging and requires specific equipment and chemical handling precautions. The creation begins with the sol-gel process, which involves mixing precursor chemicals, often based on silica, to form a wet gel. This wet gel must then undergo a lengthy solvent exchange process, where the initial water is gradually replaced with a safer solvent like ethanol over several days.
The most difficult hurdle is the drying phase, as simply letting the solvent evaporate will cause the internal structure to shrink and crack due to surface tension, resulting in a dense, non-aerogel material. To achieve a true aerogel, the sample must be dried using a supercritical fluid, typically carbon dioxide, in a high-pressure vessel. This specialized supercritical drying equipment is not standard household gear, and acquiring the necessary high-pressure components and chemicals is a major barrier for the average person. Some precursor chemicals, like TMOS, can be difficult for individuals to purchase and require adequate ventilation and safety gear due to potential health hazards.