There was pretty big hoopla last week about two papers concerning graphene (and it's related material graphene oxide). In Science, Andre Geim's group reported a remarkable result concerning a membrane made from a "paper" comprising layers of graphene oxide flakes. This membrane is apparently extremely leak-tight for gases including the notoriously slippery helium, but essentially transparent (!) to the transport of water vapor. This is very very odd. The argument made by the authors is that the graphene oxide layers are wet by physisorbed water, which can move across the graphene surface nearly frictionlessly (since graphene itself is hydrophobic - that is, it's nonpolar and doesn't interact particularly strongly with the polar water molecules). When the water is removed, the layers compress against one another tightly enough that there are no continuous pathways large enough to allow helium diffusion (or they're clogged up with residual adsorbed water). Assuming this is right, it's pretty cool, and brings to mind the ideal "semipermeable membrane" that's sometimes used as a teaching concept in thermodynamics classes. (Old joke: how do you catch a lion in the desert? A thermodynamicist would take a semipermeable membrane that passes everything except lions, and drag it across the desert to the entrance of a cage. A mathematician would simply map the exterior of the cage to the interior of the cage. Etc.)
Now, the other paper that got a decent amount of attention was this one. The interactions of water with a solid surface are often characterized by a "contact angle", the angle (inside the droplet) with which the water-air interface meets the solid-air interface. When a droplet on a surface "beads up", that angle exceeds 90 degrees (the surface is hydrophobic), while when a droplet wets the surface well, that angle is much less than 90 degrees (the surface is hydrophilic). The authors of this paper claim that a monolayer of graphene on a surface leaves the contact angle completely undisturbed (for surfaces where there is not chemical bonding at work between water and the surface). That's extremely weird, especially in light of the previous paragraph. You'd have to have a situation where the surface interactions of water with graphene are completely determined by the material under the graphene, not by the graphene itself. That is, somehow having graphene there doesn't affect the van der Waals interaction much at all. This is surprising, given past experiments that look at, e.g., the interactions of nanotubes with graphite surfaces, where clearly the van der Waals interaction is nontrivially tied to the graphene geometry, for example. I have a tough time understanding how the interpretations of both of these papers can be correct, though just because it's unintuitive to me doesn't mean it's not true.
(Bonus question: can any of the commenters identify the quote that I used for the title of this post?)