As you may have heard, graphene is awesome. This single layer of carbon atoms arranged as a honeycomb crystal lattice is both the thinnest material we’ve ever discovered and the strongest one compared to a similar thickness of anything else (even old Nokia phones). It conducts both heat and electricity better than anything else yet measured, and is both the stiffest and yet the most ductile. It’s for these reasons graphene experiments earned Andre Geim and Konstantin Novoselov the 2010 Nobel Prize in Physics. Now a team at the University of Manchester led by Andre Geim and Rahul Nair has found another incredible property of graphene: it can be made superpermeable to water vapor while locking in everything else.
For their experiment, the team build a laminate out of sheets of graphene oxide. The laminate was much thinner than a human hair but was still very strong and flexible. The laminate was used to seal a metal container; then they studied which gases were able to escape the container. Not even tiny helium molecules escaped, and yet water vapor passed through the laminate at the same rate as water vapor escaped an uncovered metal container. Rahul Nair offered an explanation I’ll pretend I understand:
“Graphene oxide sheets arrange in such a way that between them there is room for exactly one layer of water molecules. They arrange themselves in one molecule thick sheets of ice which slide along the graphene surface with practically no friction. If another atom or molecule tries the same trick, it finds that graphene capillaries either shrink in low humidity or get clogged with water molecules.” [Manchester]
*puffs pipe, adjusts cravat* Yes. Quite. What he said. Indeed.
Andre Geim added, “Helium gas is hard to stop. It slowly leaks even through a millimetre-thick window glass but our ultra-thin films completely block it. At the same time, water evaporates through them unimpeded. Materials cannot behave any stranger. [...] The properties are so unusual that it is hard to imagine that they cannot find some use in the design of filtration, separation or barrier membranes and for selective removal of water.”
The researchers may have already found one prize-worthy use for the laminate: making vodka stronger. Nair said, “Just for a laugh, we sealed a bottle of vodka with our membranes and found that the distilled solution became stronger and stronger with time. Neither of us drinks vodka but it was great fun to do the experiment.” You know what would be even more fun? Drinking that vodka.