Single layers of graphite, known as graphene sheets, have been predicted to have excellent electrical, mechanical, thermal, and other properties, so dispersing these sheets in a polymer matrix could lead to exceptional electrically conductive composites. The problem is that the sheets tend to stick together, yielding clumpy materials. Now, a team at Northwestern University led by physical chemist Rodney S. Ruoff has solved that problem. The researchers first convert graphite into graphite oxide, which is then derivatized with phenyl isocyanate. This treatment allows the material to be separated into single sheets that can readily be dispersed in solutions of commercial polymers in polar organic solvents. A final reduction step yields a composite with excellent structural and electrical characteristics, according to the team (Nature 2006, 442, 282). A polystyrene-graphene composite they produced that contains only 1% graphene by volume offers a conductivity sufficient for many electrical applications, they report. These graphene composites aren't yet as electrically conductive as carbon nanotube materials, but they could be much less costly, comments Nicholas A. Kotov of the University of Michigan.