Most electrically conductive materials, he points out, are hydrophilic: Water spreads readily on them, thoroughly wetting the surface. "On the other hand," he says, "for many electronic and military applications, it is important to fabricate hydrophobic, electrically conductive surfaces." And while graphene's transparency to wettability is not perfect, it may still be good enough for such applications, he says.
This research, which included both theoretical modeling and experimental confirmation, shows that by depositing a large graphene sheet, grown by a process called chemical vapor deposition, on another material's surface, "it would be possible to induce electrical conductivity on the surface, while partially preserving the desired surface wetting behavior," Blankschtein says. In fact, he adds, the contact angle of such a surface the measure of how well it prevents wetting "is believed to be one of the highest attainable on a flat, electrically conductive surface to date."
Shih, the lead author of the paper, says, "We have demonstrated that the wettability of a transparent, graphene-coated surface can be manipulated without undermining its thermal/electrical conductivity." That's useful because "in general, conductive surfaces have very high wettability due to their high surface tension, and it is generally very challenging to produce a thermally/electrically conductive surface with tunable wettability" wettability that can be controlled almost at will.
The team describes this partial transmission of the underlying characteristics as "translucency," rather than transparency, of wettability.
By selecting a particular combination of an underlying material with a graphene coating, different combinations of electrical, optical and wetting characteristics can be achieved, Shih says: "People can control the wetting properties of the substrate this breakthrough successfu
|Contact: Caroline McCall, MIT Media Relations|
Massachusetts Institute of Technology