Graphene exhibits a surprisingly strong attraction to the interface of two immiscible solvents, which is interesting from both a fundamental and an application point of view. At the heptane/water interface graphite particles spontaneously exfoliate into thinner and thinner sheets due to this interaction, which can be used to mass-produce pristine graphene at bulk quantities, but also to make conductive graphene surface coatings at a large scale. Moreover, this high degree of surface activity of graphene can be used to stabilize liquid/liquid interfaces, giving rise to the notion of graphene sheets as surfactants, albeit with a 2D morphology. This property can be exploited for Pickering emulsions with novel properties tuned by the geometry of the employed graphene sheets. Based on such emulsions we have successfully produced graphene-based foams, polymer nanocomposites, and other structures of various geometries. <br/>We have used force spectroscopy to study the interactions of graphene with the liquid/liquid interface in a rigorous way. Therefore, we functionalized colloidal atomic force microscopy probes and moved them relative to the interface of pinned droplets. Analysis of force spectroscopy results at this interface is then used to improve our understanding of the peculiar behavior of graphene observed under such conditions. Our experimental efforts at the nano- and macroscale are complemented by calculations and molecular dynamics simulations.<br/>To characterize the obtained graphene surface coatings we also developed a low-cost, high-throughput optical method, which rapidly provides the lateral dimensions of thousands of graphene sheets, as well as their thickness with single-layer resolution. In addition, the method has enough sensitivity to characterize the oxidation state of graphene sheets with different degrees of functionalization. This optical method is universally applicable to other 2D materials. <br/>

Graphene as a two-dimensional surfactant

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.