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:
Graphene Composites, a UK-based company developing graphene-enhanced bulletproof shields, has exceeded its crowdfunding target. GC attempted to raise £300,000 on Crowdcube, but ended up raising £510,680 (around 676,625 USD).
Once Graphene Composites had hit its crowdfunding target, the company sent out a message to its supporters saying: “Thank You - by investing in GC, you have not only invested in a company that should provide you with a healthy return and strong dividends, you are also enabling us to develop and deliver products that will truly improve the quality of life for many around the world. For example, our GC Shield active shooter protection in schools now, and eventually our Lightning Harvester renewable energy sources. Thank You, from all of us on the GC Team”.
Australia-based advanced materials technology company, Talga Resources, has reported outstanding conductivity results from its Talphene-enhanced epoxy composite trials undertaken at TWI in the UK. Carbon fiber reinforced polymer (“CFRP”) panels were constructed using a dispersion of Talga graphene (Talphene) in the epoxy-based resin of the composite and subjected to a range of conductivity tests pertinent to aircraft applications.
Results reported by Talga showed the Talphene panel provided similar lightning strike protection as copper mesh panels currently used in composite aircraft but saved 75% of the weight of the copper. Further results demonstrating Talphene’s significant conductivity included up to 500% increase in dielectric constant, 100% increase in resin thermal conductivity as well as spot temperatures well over 100 degrees celsius in anti-icing trials.
Rice University scientists have developed a graphene-based epoxy for electronic applications. Epoxy combined with graphene foam invented in the Rice lab of Prof. James Tour) is reportedly substantially tougher than pure epoxy and far more conductive than other epoxy composites, while retaining the material's low density. It could improve upon epoxies in current use that weaken the material's structure with the addition of conductive fillers.
By itself, epoxy is an insulator, and is commonly used in coatings, adhesives, electronics, industrial tooling and structural composites. Metal or carbon fillers are often added for applications where conductivity is desired, like electromagnetic shielding. The trade-off, however, is that more filler brings better conductivity at the cost of weight and compressive strength, and the composite becomes harder to process. The Rice solution replaces metal or carbon powders with a 3D foam made of nanoscale sheets of graphene.
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.”