Department of Physics, Lancaster University, Lancaster, United Kingdom, Materials Science Institute, Lancaster University, Lancaster, United Kingdom, Department of Chemistry, Durham University, Durham, United Kingdom, CEA, LETI 17 Rue des Martyrs, Grenoble, France, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom, Department of Physics of Complex Systems, Eötvös University, Pázmány Péter Sétány 1/A, Budapest, Hungary

"Graphene and related two-dimensional (2D) materials possess outstanding electronic and mechanical properties, chemical stability, and high surface area. However, to realize graphene's potential for a range of applications in materials science and nanotechnology there is a need to understand and control the interaction of graphene with tailored high-performance surfactants designed to facilitate the preparation, manipulation, and functionalization of new graphene systems. Here we report a combined experimental and theoretical study of the surface structure and dynamics on graphene of pyrene-oligoethylene glycol (OEG) -based surfactants, which have previously been shown to disperse carbon nanotubes in water. Molecular self-assembly of the surfactants on graphitic surfaces is experimentally monitored and optimized using a graphene coated quartz crystal microbalance in ambient and vacuum environments. Real-space nanoscale resolution nanomechanical and topographical mapping of submonolayer surfactant coverage, using ultrasonic and atomic force microscopies both in ambient and ultrahigh vacuum, reveals complex, multilength-scale self-assembled structures. Molecular dynamics simulations show that at the nanoscale these structures, on atomically flat graphitic surfaces, are dependent upon the surfactant OEG chain length and are predicted to display a previously unseen class of 2D self-arranged ""starfish"" micelles (2DSMs). While three-dimensional micelles are well-known for their widespread uses ranging from microreactors to drug-delivery vehicles, these 2DSMs possess the highly desirable and tunable characteristics of high surface affinity coupled with unimpeded mobility, opening up strategies for processing and functionalizing 2D materials. © 2017 American Chemical Society."

2D micelles, graphene, molecular dynamics, scanning probe microscopy, surfactants

Atomic force microscopy, Carbon, Chemical stability, Crystal atomic structure, Micelles, Molecular dynamics, Nanotechnology, Scanning probe microscopy, Self assembly, Surface active agents, Yarn, Drug delivery vehicles, Molecular dynamics simulations, Molecular self assembly, Nanoscale resolutions, Oligoethylene glycols, Self assembled structures, Structure and dynamics, Two Dimensional (2 D), Graphene