Graphene oxide: a surfactant or particle?

Graphene oxide is a two-dimensional carbon nanomaterial that has risen to prominence over the last decade as graphenes water-dispersible counterpart. This key feature offers tremendous potential in the formation of waterborne hybrid materials, coatings, membranes and adsorbents that make use of its diverse surface chemistry and extraordinary surface area. However, the fundamental colloidal properties of graphene oxide remain incompletely understood, with conflicting reports on how the material's amphiphilic nature and adsorption at interfaces render it surfactant-like or particle-like in nature. In the present work, recent developments in understanding the bulk and interfacial colloidal properties of graphene oxide are explored in the context of its chemistry and system thermodynamics, giving insight into the fundamental question of whether its aqueous behaviour is most accurately described as particle-like, surfactant-like or indeed something entirely different.