3 research outputs found
Particles adsorbed at various non-aqueous liquid-liquid interfaces
Particles adsorbed at liquid interfaces are commonly used to stabilise water-oil Pickering emulsions and water-air foams. The fundamental understanding of the physics of particles adsorbed at water-air and water-oil interfaces is improving significantly due to novel techniques that enable the measurement of the contact angle of individual particles at a given interface. The case of non-aqueous interfaces and emulsions is less studied in the literature. Non-aqueous liquid-liquid interfaces in which water is replaced by other polar solvents have properties similar to those of water-oil interfaces. Nanocomposites of non-aqueous immiscible polymer blends containing inorganic particles at the interface are of great interest industrially and consequently more work has been devoted to them. By contrast, the behaviour of particles adsorbed at oil-oil interfaces in which both oils are immiscible and of low dielectric constant (Δ < 3) is scarcely studied. Hydrophobic particles are required to stabilise these oil-oil emulsions due to their irreversible adsorption, high interfacial activity and elastic shell behaviour
Interfacial Activity and Contact Angle of Homogeneous, Functionalized, and Janus Nanoparticles at the Water/Decane Interface
Surface heterogeneity affects the
behavior of nanoparticles at
liquid interfaces. To gain a deeper understanding on the details of
these phenomena, we have measured the interfacial activity and contact
angle at water/decane interfaces for three different types of nanoparticles:
homogeneous polyÂ(methyl methacrylate) (PMMA), silica functionalized
with a capping ligand containing a methacrylate terminal group, and
Ag-based Janus colloids with two capping ligands of different hydrophobicity.
The interfacial activity was analyzed by pendant drop tensiometry,
and the contact angle was measured directly by freeze-fracture shadow-casting
cryo-scanning electron microscopy. The silver Janus nanoparticles
presented the highest interfacial activity, compared to the silica
nanoparticles and the homogeneous PMMA nanoparticles. Additionally,
increasing the bulk concentration of the PMMA and silica nanoparticles
up to 100-fold compared to the Janus nanoparticles led to silica particles
forming fractal-like structures at the interface, contrary to the
PMMA particles that did not show any spontaneous adsorption