When the GO droplets hit the surface of the CTAB solution, they behave very similarly to when a jet of hot smoke hits cold air. This was achieved by dropping the GO dispersion in water in the form of small droplets into a solution of CTAB in water. The researchers used a second liquid crystal material called CTAB (cetyltrimethylammonium bromide), to aggregate GO flakes into small particles of graphene oxide hydrogels, without needing to reduce them to graphene. Such porous 3-dimensional assemblies of GO are called aerogels, and when filled with water, they are called hydrogels. However, to be useful, they need to be assembled into complex 3-dimensional shapes which preserves their high surface area and surface chemistry. Individual GO sheets are one atom thin, and as wide as the thickness of human hair. Graphene oxide (GO), a functionalised form of graphene which forms a stable dispersion in water, has many unique properties, including being a liquid crystal. Then, by tailoring this process, we have developed very efficient particles for adsorptive purification of contaminants from water”. Prof Vijayaraghavan said: “We have undertaken a systematic study to understand and explain the influence of various parameters and forces involved in the particle formation. The researchers have shown that the formation of these graphene particles is governed by a complex interplay between different forces such as viscosity, surface tension, inertia and electrostatics. These particles have also been shown to be exceptionally efficient in adsorbing contaminants from water, thereby purifying it.
The same effect is used to produce smoke rings and is responsible for keeping dandelion seeds flying. Writing in the Journal of Molecular Liquids, a team led by Professor Aravind Vijayaraghavan based in the National Graphene Institute (NGI) have produced 3-dimensional particles made of graphene, of many interesting shapes, using a variation of the vortex ring effect.
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