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Abstract:

Graphene has been called ‘a rising star of material science and condensed matter physics’1. The great attention that it has gained in the field of physics is due to its 2-dimensional nature, which allows to design systems with highly dense structures and yet high surface area (almost close to theoretical limit), good electronic properties and high mechanical strength (greater than carbon nanotubes), etc. Most of the past research has been focused on the mechanical properties of individual sheets and of composite materials. Yet, the 2-dimensional nature of graphene sheets and its effects on the behavior in complex systems has not been addressed explicitly. In this work we investigate the behavior of functionalized graphene sheets (FGS) at the interface as a mean of exploiting the bi-dimensional nature of the sheets in a bi-dimensional assembly: we show how graphene is a strong surface-active material and how it can be used as a low cost and high yield emulsion stabilizer. Moreover we present the rheology of water-in-oil emulsions in both oscillatory and steady shear measurements. The strong compressibilities of the FGS-laden interfaces and highly elastic behavior of emulsions are searched in the compressibility and elasticity of the single sheet itself , thorough measurements of the dichroism of FGS under oscillatory shear flow.