Particle-laden interfaces can be used to stabilize a variety of high-interface systems, from foams over emulsions to polymer blends. The relation between the particle interactions, the structure and rheology of the interface, and the stability of the system remains unclear. In the present work, we experimentally investigate how micron-sized, near-hard-sphere-like particles affect the mechanical properties of liquid interfaces. In particular, by comparing dried and undried samples, we investigate the effect of aggregation state on the properties of the particle-laden liquid interface and its relation to the stability of the corresponding Pickering emulsions. Partially aggregated suspensions give rise to a soft-solid-like response under shear, whereas for stable PMMA particulate layers a liquid-like behavior is observed. For interfacial creep-recovery measurements, we present an empirical method to correct for the combined effect of the subphase drag and the compliance of the double-wall ring geometry, which makes a significant contribution to the apparent elasticity of weak interfaces. We further demonstrate that both undried and dried PMMA particles can stabilize emulsions for months, dispelling the notion that particle aggregation, in bulk or at the interface, is required to create stable Pickering emulsions. Our results indicate that shear rheology is a sensitive probe of colloidal interactions but is not necessarily a predictor of the stability of interfaces, e.g., in quiescent Pickering emulsions, as in the latter the response to dilatational deformations can be of prime importance.

combined with its production by expensive vapor processing methods define an urgent need for alternative materials. One possible alternative material for this is graphene, [3] a 2D allotrope of carbon first described in 2004. [4] Composed of a single layer of carbon atoms, graphene offers high mechanical strength, chemical resistance, and thermal and electrical conductivity while maintaining high optical transparency. [5] What remains a challenge, however, is its exfoliation from bulk graphite in scalable quantity such that applications no longer rely upon expensive bottom-up growth methods such as chemical vapor deposition. [6] Liquid-phase exfoliation of cheap and plentiful bulk graphite provides a low-cost exfoliation method with reported yields typi cally ranging from less than 1% up to 10% by mass of single-or few-layer graphene in organic solvents. [7][8][9][10] Graphite exfoliation by oxidation to nonconductive graphene oxide (GO), followed by reduction to restore sp 2 conjugation in the material, has the benefit of readily producing single sheets of GO in aqueous dispersion. Subsequent reduction, however, is only partial and often accompanied by significant loss of mass of the GO, resulting in compromised electrical and mechanical properties. [11][12][13] Therefore, a method of directly exfoliating bulk graphite to graphene using a very mild electrochemical oxidation [8,14] has the best potential for high yield and good electrical quality. Moreover, a liquid dispersion provides the optimal starting point for fabrication of graphene films prepared using liquid-based film processing techniques.Langmuir-Blodgett deposition is one such technique, capable of fabricating monolayer or multilayer films with well-ordered structures templated on the liquid interface and then transferred to a substrate of choice. Structural control stems from manipulation of the surface pressure of the interfacial material by compression with mechanical barriers, before the substrate is raised or lowered through the interface. Knowledge of the 2D phase behavior and compression state of the material is an important prerequisite for depositing a film with controlled properties. Applicable to a wide range of interfacial systems, it has long been a standard laboratory-scale technique to coat appropriate substrates, including flexible ones, for further analysis and characterization of interfacial films. [15] The combination of low cost and environmental impact with the efficiency of material transfer from the interface to the substrate has meant that interest Confinement of particles to fluid-fluid interfaces provides a unique interaction environment, allowing the directed assembly of particles using lateral capillary forces. The particle laden interfacial layers can be deposited onto a variety of substrates for the fabrication of thin film coatings, designed to have structural or functional properties resulting from the interfacespecific structures. For the fabrication of electrically conducting films and specifically graphene-based co...