Extreme thinness of graphene makes it 'invisible' to water

Graphene is the thinnest material known to science, and understanding how it interacts with moisture was the impetus behind this study.

The engineering researchers at Rensselaer Polytechnic Institute and Rice University coated pieces of gold, copper and silicon with a single layer of graphene and then placed a drop of water on the coated surfaces. The layer of graphene proved to have virtually no impact on the way in which water spread on the surfaces.

The findings, published in Nature Materials, could help inform a new generation of graphene-based flexible electronic devices. In addition, the research suggests that a new type of heat pipe that uses graphene-coated copper to cool computer chips could be developed.

Prof Nikhil Koratkar, co-author of the paper from the Department of Mechanical, Aerospace and Nuclear Engineering and the Department of Materials Science and Engineering at Rensselaer, said: ‘The graphene was completely transparent to the water. The single layer of graphene was so thin that it did not significantly disrupt the non-bonding van der Waals forces that control the interaction of water with the solid surface.’

Graphene comprises a single layer of carbon atoms arranged like a nanoscale chicken-wire fence. The material is strong, tough and highly flexible, which makes it an attractive material to coat surfaces with.

Many researchers and technology leaders see graphene as an enabling material that could greatly advance the advent of flexible, paper-thin devices and displays. Used as a coating for such devices, the graphene would certainly come into contact with moisture.

The research was supported in part by the Advanced Energy Consortium (AEC), the National Science Foundation (NSF) and the Office of Naval Research (ONR) Graphene Multidisciplinary University Research Initiative (MURI).