A non-equilibrium state diagram for liquid/fluid/particle mixtures

Abstract

The equilibrium structures of ternary oil/water/surfactant systems are often represented within a triangular composition diagram with various regions of the triangle corresponding to different equilibrium states. We transplant this idea to ternary liquid/fluid/particle systems that are far from equilibrium. Liquid/liquid/particle mixtures or liquid/gas/particle mixtures yield a wide diversity of morphologies including Pickering emulsions, bijels, pendular aggregates, spherical agglomerates, capillary suspensions, liquid marbles, powdered liquids, and particle-stabilized foams. This paper argues that such ternary liquid/fluid/particle mixtures can be unified into a non-equilibrium state diagram. What is common among all these systems is that the morphology results from an interplay between the preferential wettability of the particles, capillarity, and viscous forces encountered during mixing. Therefore all such systems share certain universal features, regardless of the details of the particles or fluids used. These features guide the construction of a non-equilibrium state diagram which takes the form of a triangular prism, where each triangular cross-section of the prism corresponds to a different relative affinity of the particles towards the two fluids. We classify the prism into regions in which the various morphologies appear and also emphasize the major difference between systems in which the particles are fully-wetted by one of the fluids vs. partially-wetted by both fluids. We also discuss how the state diagram may change with mixing intensity or with interparticle attractions.

Shrinkage and dimensional accuracy of porous ceramics derived from capillary suspensions

“…As previously shown for alumina-based and other capillary suspensions [21,[29][30][31], we observed an increase in yield stress with increasing amounts of secondary phase in the pendular state as the size of the capillary bridges and their number increases, and then a peak and subsequent reduction in the yield stress as the bridges coalesce in the funicular state, as shown in Fig. 1.…”

Preparation and yielding behavior of pendular network suspensions

“…In such particulate systems with capillarity, the wettability of the particles toward the minority liquid plays a crucial role in determining the suspension microstructure [15,28,29]. The above-mentioned case of wet sand is, in this article, dubbed the fully wetting situation, i.e., the particles are fully wetted by the minority liquid, water.…”

Stabilization of Oil-in-Water Emulsions with Noninterfacially Adsorbed Particles

“…Rigid particle network formation in the coherent phase has been demonstrated by several researchers to impact emulsion stability. 5,16,30,36 High frame rate imaging of the particle dynamics in the coherent phase near to the droplet surfaces in this work confirms that the bare-silica NPs exhibit Brownian motion, so rigid network formation may 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 16 be dismissed. Upon initial inspection, one may suspect that the dispersion of NPs into the coherent phase would result in attractive depletion forces between the oil droplets due to volume exclusion effects and subsequent destabilization of the emulsion.…”