Controlling Self-Assembly of Reduced Graphene Oxide at the Air–Water Interface: Quantitative Evidence for Long-Range Attractive and Many-Body Interactions

• Published in: ACS applied materials & interfaces Vol. 7; no. 6; pp. 3807 - 3815
• Main Authors: Silverberg, Gregory J, Pearce, Phoebe, Vecitis, Chad D
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 18-02-2015
• Subjects: reduced graphene oxide; air−water interface; graphene films; DLVO theory; colloidal self-assembly; capillary interactions
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/am5087984

Industrial-scale applications of two-dimensional materials are currently limited due to lack of a cost-effective and controlled synthesis method for large-area monolayer films. Self-assembly at fluid interfaces is one promising method. Here, we present a quantitative analysis of the forces governing reduced graphene oxide (rGO) assembly at the air–water interface using two unique approaches: area-based radial distribution functions and a theoretical Derjaguin–Landau–Verwey–Overbeek (DLVO) interaction potential for disks interacting edge-to-edge. rGO aggregates at the air–water interface when the subphase ionic strength results in a Debye screening length equal to the rGO thickness (∼1 mM NaCl), which is consistent with the DLVO interaction potential. At lower ionic strengths, area-based radial distribution functions indicate that rGO–rGO interactions at the air–water interface are dominated by long-range (tens of microns) attractive and many-body repulsive forces. The attractive forces are electrostatic in nature; that is, the force is weakened by minor increases in ionic strength. A quantitative understanding of rGO–rGO interactions at the air–water interface may allow for rational synthesis of large-area atomically thin films that have potential for planar electronics and membranes.