Robinson, Benjamin and Kay, Nicholas and Kolosov, Oleg (2014) Nanoscale interfacial interactions of graphene with polar and non-polar liquids. In: EMRS 2014, Spring Meeting, 2014-05-262014-05-30, France.
Full text not available from this repository.Abstract
Graphene’s nanomechanical behaviour in liquids, vital for its operation in rechargeable batteries, super-capacitors, and sensors, is still largely unexplored. Here we will discuss the results of recent studies investigating the nanomechanics of normal (adhesive and elastic) and tangential (friction) forces between a stationary, moving and ultrasonically excited nanoscale atomic force microscope (AFM) tip and exfoliated few layer graphene (FLG) on SiO2 substrate as a function of surrounding media – air, polar (water) and non-polar (dodecane) liquids. We find that while the friction coefficient is significantly reduced in liquids, and is always lower for FLG than SiO2, it is higher for graphene in non-polar dodecane than highly polar water. We also confirm that in ambient environment the water meniscus dominates high adhesion for both hydrophobic FLG and the more hydrophilic SiO2 surface. By using nanomechanical probing via ultrasonic force microscopy (UFM) we observed profound reduction of graphene rippling and increase of graphene-substrate contact area in liquid environment. Friction force dependence on ultrasonic modulation amplitude suggests that dodecane at the graphene interface produces a solid-like “cushion” of approximately 2 nm thickness, whereas in water immersion, the same dependence shows remarkable similarity with ambient environment, confirming the presence of water meniscus in air, and suggesting negligible thickness of a similar water “cushion” on graphene.