Dependence of the shape of graphene nanobubbles on trapped substance

• Published in: Nature communications Vol. 8; no. 1; p. 15844
• Main Authors: Ghorbanfekr-Kalashami, H., Vasu, K. S., Nair, R. R., Peeters, François M., Neek-Amal, M.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 16.06.2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/357/1018; 639/925/918/1053; Adhesion; Asymmetry; Atomic force microscopy; Atomic radius; Bubbles; Crystals; Graphene; Hexadecane; Humanities and Social Sciences; Hydrocarbons; Microscopy; Molecular dynamics; multidisciplinary; Nanostructure; Phase transitions; Pressure; Science; Science (multidisciplinary); Simulation; Symmetry
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms15844

Van der Waals (vdW) interaction between two-dimensional crystals (2D) can trap substances in high pressurized (of order 1 GPa) on nanobubbles. Increasing the adhesion between the 2D crystals further enhances the pressure and can lead to a phase transition of the trapped material. We found that the shape of the nanobubble can depend critically on the properties of the trapped substance. In the absence of any residual strain in the top 2D crystal, flat nanobubbles can be formed by trapped long hydrocarbons (that is, hexadecane). For large nanobubbles with radius 130 nm, our atomic force microscopy measurements show nanobubbles filled with hydrocarbons (water) have a cylindrical symmetry (asymmetric) shape which is in good agreement with our molecular dynamics simulations. This study provides insights into the effects of the specific material and the vdW pressure on the microscopic details of graphene bubbles. Graphene nanobubbles can act as enclosures for holding small volumes of substances. Here the authors find a correlation between bubble shape and the encapsulated material providing a potential method for determining the graphene bubble content by its deformation.