What is aerogel?
Aerogel is created by combining a polymer with a solvent to form a gel, and then removing the liquid from the gel and replacing it with gas (usually air). The high air content (99.98% air by volume) makes it one of the world's lightest solid material. Aerogels can be made from a variety of chemical compounds, and are a diverse class of materials with unique properties. They are known as excellent insulators, and usually have low density and low thermal conductivity.
Aerogels can be used in various applications, and although they have been around since the 1930s, their development is still progressing (for example, NASA's Glenn Research Center in Cleveland has invented several groundbreaking methods of creating new types of aerogels).
Common applications include enhancing the thermal performance of energy-saving materials and sustainable products for buildings, acting as a high performance additive to coatings, prevention of corrosion under insulation, uses in imaging devices, optics, and light guides, thermal breaks and condensation control, architectural lighting panels, outdoor and sports gear and clothing, and more.
Graphene aerogel, also known as aerographene, is considered to be the least dense solid in existence (graphene aerogels are light enough to be balanced on small plants!).
Graphene aerogels are quite elastic and can easily retain their original form after some compression. In addition, the low density of graphene aerogels makes them very absorbent (to the point where it can even absorb more than 850 times its own weight). This means that it could be useful for environmental clean-ups like oil spills, and the aerogels only need to be picked up later after absorbing the spilled material. Graphene aerogel may also have some applications in both the storage and the transfer of energy by enabling the creation of lighter, higher-energy-density batteries - and vigorous research is being done on the matter.
Graphene aerogel are somewhat similar to graphene foams. Graphene foams are usually made by CVD growth on a metal structure (which is later removed), and are so more conductive than graphene aerogels.
Graphene aerogels are already being sold commercially, for about about $300 per gram.
The latest Graphene Aerogel news:
Researchers at the University of California, Santa Cruz and Lawrence Livermore National Laboratory in California have developed a new fabrication technique to make capacitors enhanced with graphene. The resulting devices store a large amount of charge over a given surface area - an important metric for measuring the performance of a capacitor.
The new technique uses a 3D printer to construct a microscopic scaffold with porous graphene and then fills the structure with a kind of material called a pseudocapacitive gel, which is a kind of capacitor material that also behaves like a battery in some ways.
Researchers from Virginia Tech and Lawrence Livermore National Laboratory have developed a new way to 3D print with graphene. Graphene has previously been used in extrusion-based processes to print single sheets and basic structures at a resolution of around 100 microns, but this latest research shows it is also possible to use a stereolithography-based technique to print “pretty much any desired structure” down to 10 microns, close to the size of actual graphene sheets. The ability to 3D print functional parts in graphene could benefit many industries and products.
“Now a designer can design three-dimensional topology comprised of interconnected graphene sheets,” said Xiaoyu “Rayne” Zheng, assistant professor with the Department of Mechanical Engineering in the College of Engineering and director of the Advanced Manufacturing and Metamaterials Lab. “This new design and manufacturing freedom will lead to optimization of strength, conductivity, mass transport, strength, and weight density that are not achievable in graphene aerogels.”
A research team led by the National University of Singapore (NUS) and conducted in collaboration with Fudan University has developed an economical and industrially viable strategy to produce graphene. The new technique may offer a way for efficient large-scale production of graphene, to pave the way for sustainable synthesis of the material.
The conventional method of producing graphene utilizes sound energy or shearing forces to exfoliate graphene layers from graphite, and then dispersing the layers in large amounts of organic solvent. As insufficient solvent causes the graphene layers to reattach themselves back into graphite, yielding one kilogram of graphene currently requires at least one tonne of organic solvent, making the method costly and environmentally unfriendly.
Researchers at Zhejiang University in China have designed a new type of aerogels, made of graphene and carbon nanotubes, that can be reversibly stretched to more than three times their original length, displaying elasticity similar to that of a rubber band. This stretchability, in addition to aerogels' existing properties like ultralow density, light weight, high porosity, and high conductivity, may lead to exciting new applications.
The scientists designed carbon aerogels consisting of both graphene and multi-walled carbon nanotubes assembled into four orders of hierarchical structures ranging from the nanometer to centimeter scale. To fabricate the material into aerogels, the researchers created an ink composed of graphene oxide and nanotubes, and then formed the aerogels via inkjet printing.
The PolyGraph project, a 4-year development project with aims to develop new production techniques to deliver industrial scale quantities of graphene-reinforced thermosetting polymers, has published its results.
The POLYGRAPH (Up-Scaled Production of Graphene Reinforced Thermosetting Polymers for Composite, Coating and Adhesive Applications) project brought together 14 partners, including SMEs, companies, universities and a research center, and has reportedly led to the identification of the most suitable materials and production techniques for graphene-based coatings, adhesives and composites. Once the graphene market reaches maturity and material prices drop , these new products could appeal to a vast range of industries.