Nanotechnologists have overcome a long-standing barrier to nanoparticle dispersion that could revolutionise the development of carbon nanomaterials for composites.

Composite materials are used in fuel cells, batteries and other electronic applications. The use of carbon nanotubes to produce nanocomposites is well established, but more recently nanoplatelets of graphite have been considered as a low-cost alternative.

water dispersions without and with polymer

Nanoplatelets are formed by exfoliation of the carbon layers that make up graphite. The platelets must be uniformly dispersed in a matrix, but forming stable dispersions of nanoplatelets in solvents has until now proven to be a challenge.

SonBinh Nguyen, Rodney Ruoff and colleagues at Northwestern University, US, have devised a technique to solve this problem using a polymer that has an affinity for both platelets and water. The polymer, poly(sodium 4-styrenesulfonate), interacts with the surface of the nanoplatelets to prevent them from sticking together and forming a precipitate.

This strategy - which can be extended to use in organic solvents - may eventually allow for the exfoliation of individual sheets that can be manipulated in solution, say the researchers.

Caroline A Moore