Wednesday, June 16, 2010

Graphene and graphene oxide - Properties

Lately there's a big fuss about graphene oxide, a single-atomic-layered material made by reacting graphite powders with strong oxidizing agents because of its ability to be easily converted into graphene, and graphene is believed by many scientists to be key material in producing low-cost carbon-based transparent and flexible electronics.

The researchers at the McCormick School of Engineering and Applied Science at Northwestern University have studied graphene for many years, and they were able to discover how to assemble these soft sheets like floating water lilies pads, and they also used a camera flash to turn them into graphene, and even invented a fluorescence quenching technique to make them visible under microscopes.

But they until know didn't know much about graphene properties. Their knowledge about graphene significantly changed after they discovered that graphene oxide sheets behave like surfactants, the chemicals in soap and shampoo that make stains disperse in water.

The lead author Jiaxing Huang said that "we view graphene oxide as a soft material, and for example, it is essentially two-dimensional polymers composed of carbon, hydrogen and oxygen. They are also colloidal particles with very exotic shapes.

Researchers found out after putting graphene oxide in carbonated water that the sheets can "hitchhike" onto the rising bubbles to reach the water surface-just like a surfactant would do. They also found that graphite oxide can disperse oil droplets in water - just like a surfactant would.

This discovery of surfactant properties that graphene has could be of great importance because graphene could be used as a dispersing agent for insoluble materials, like carbon nanotubes. Graphene would also have significant advantage over common surfactants because common surfactants are non conducting, and thus Graphite oxide, which turns into conducting graphene through heating, would actually help conductivity.

The important discovery regarding graphene was also that water surface can act as a filter for separating graphene oxide sheets by size, and this effect makes it easier to harvest large sheets of graphene oxide, which are more useful for graphene device fabrication.

Graphene has surfactant properties