Interfacial rheology insights: particle texture and Pickering foam stability

Abstract

Interfacial rheology studies were conducted to establish a connection between the rheological characteristics of particle-laden interfaces and the stability of Pickering foams. The behavior of foams stabilized with fumed and spherical colloidal silica particles was investigated, focusing on foam properties such as bubble microstructure and liquid content. Compared to a sodium dodecyl sulfate-stabilized foam, Pickering foams exhibited a notable reduction in bubble coarsening. Drop shape tensiometry measurements on particle-coated interfaces indicated that the Gibbs stability criterion was satisfied for both particle types at various surface coverages, supporting the observed arrested bubble coarsening in particle-stabilized foams. However, although the overall foam height was similar for both particle types, foams stabilized with fumed silica particles demonstrated a higher resistance to liquid drainage. This difference was attributed to the higher yield strain of interfacial networks formed by fumed silica particles, as compared to those formed by spherical colloidal particles at similar surface pressures. Our findings highlight that while both particles can generate long-lasting foams, the resulting Pickering foams may exhibit variations in microstructure, liquid content, and resistance to destabilization mechanisms, stemming from the respective interfacial rheological properties in each case.

Design of Janus Nanoparticles for Mobility Control in Heterogeneous Reservoirs

“…As the temperature increases, the viscosity of the emulsion decreases and a second flow region appears. This is due to the increase in temperature causing the long alkyl chains on SiO 2 to transform from an ordered to a disordered state, reducing the thickness and density of the solvent coating layer, and simultaneously decreasing the van der Waals attraction between the particles. − Figure b demonstrates the viscosity of crude oil and emulsion stabilized by 3NSI16W particles at 80 °C. The crude oil shear-thinned at a low shear rate, then underwent shear-thickening, and finally the viscosity stabilized, with the characteristics of an approximate Newtonian fluid.…”

Janus particle amphiphilicity and capillary interactions at a fluid interface

“…To extract information on the mechanical properties of the network, the resulting surface pressure isotherms were further analyzed to calculate the isothermal surface compressibility coefficient, of the interfacial network as a function of the JP amphiphilicity 85 . To further examine the link between JP amphiphilicity, the overall interparticle interactions experienced by the particles within the network, and the resulting surface pressures, a surface equation of state was used to interpret the surface pressure isotherms 86 .…”

“…T of the interfacial network as a function of the JP amphiphilicity. 85 To further examine the link between JP amphiphilicity, the overall interparticle interactions experienced by the particles within the network, and the resulting surface pressures, a surface equation of state was used to interpret the surface pressure isotherms. 86 As shown by Fainerman et al, the surface pressure of a micron-sized particle monolayer can be related to the particle surface coverage and interparticle interaction parameter via the following equation:…”

Effects of Nanoparticle Wettability on the Meniscus Stability of Oil–Water Systems: A Coarse-Grained Modeling Approach

“…In addition to their impact on surface wettability, NPs can influence the rheological properties of fluid–fluid interfaces depending on their size, shape, surface roughness, and anisotropy, − which can be employed in tuning the stability of emulsions and foams. , Among different types of NPs, Janus particles (JPs) stand out, as they combine surface anisotropy and amphiphilicity into a single particle. Because one face of the JPs is hydrophilic and the other is hydrophobic, they exhibit special properties at fluid interfaces.…”