Tiny balloons made from the one-atom-thick carbon material known as graphene can withstand enormous pressures, much higher than those at the bottom of the deepest ocean, report scientists at the University of Manchester. This is due to graphene's incredible strength – 200 times stronger than steel.
Graphene balloons form routinely when graphene is placed on flat substrates, but they are usually considered a nuisance and therefore ignored. The Manchester scientists, led by Irina Grigorieva, decided to take a closer look at the nano-bubbles and discovered they are capable of withstanding enormous pressures. This finding could be a significant step towards rapidly detecting how molecules react under extreme pressure.
Writing in Nature Communications, the scientists report that the shape and dimensions of the nano-bubbles provide straightforward information about both graphene's elastic strength and its interaction with the underlying substrate. The researchers also found that such balloons can be created with other two-dimensional crystals, such as single layers of molybdenum disulfide (MoS2) or boron nitride.
"Those balloons are ubiquitous. One can now start thinking about creating them intentionally to change enclosed materials or study the properties of atomically thin membranes under high strain and pressure."Sir Andre Geim, University of Manchester
Grigorieva and her colleagues were able to measure directly the pressure exerted by graphene on a material trapped inside the balloons, or vice versa. To do this, they used the tip of an atomic force microscope to indent balloons made from graphene, monolayer MoS2 and monolayer boron nitride, measuring the force necessary to make a dent of a certain size.
These measurements revealed that graphene bubbles of 1µm in size can withstand pressures as high as 200 megapascals, or 2000 atmospheres. Even higher pressures are expected for smaller bubbles.
"Such pressures are enough to modify the properties of a material trapped inside the bubbles and, for example, can force crystallization of a liquid well above its normal freezing temperature," said Ekaterina Khestanova, a PhD student who carried out the experiments.
"Those balloons are ubiquitous. One can now start thinking about creating them intentionally to change enclosed materials or study the properties of atomically thin membranes under high strain and pressure," said Sir Andre Geim, a co-author of the paper and one of the original discoverers of graphene.
This story is adapted from material from the University of Manchester, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.