Interfacial Layer Properties of a Polyaromatic Compound and its Role in Stabilizing Water-in-Oil Emulsions

Abstract

Physical properties of interfacial layers formed at the water-xylene interface by the adsorption of a polyaromatic organic compound, N-(1-hexylheptyl)-N'-(5-carbonylicpentyl) perylene-3,4,9,10-tetracarboxylic bisimide (in brief C5Pe), were studied systematically. The deprotonation of the carboxylic group of C5Pe at alkaline pH made it highly interfacially active, significantly reducing the water-xylene interfacial tension. Thin liquid film experiments showed a continuous build-up of heterogeneous C5Pe interfacial layers at water-xylene interfaces, which contributed to the formation of stable W/O emulsions. Continual accumulation and rearrangement of C5Pe aggregates at the water-xylene interface to form a thick layer was confirmed by in-situ Brewster angle microscopy (BAM) and atomic force microscopy (AFM). The rheology measurement of the interfacial layer by double wall ring interfacial rheometry under oscillatory shear showed that the interfacial layers formed from high C5Pe concentrations were substantially elastic and rigid. The presence of elastically dominant interfacial layers of C5Pe led to the formation of stable water-inxylene emulsions.Keywords: polyaromatic surface active compound, water-in-oil emulsions; thin liquid films; insitu Brewster angle imaging; interfacial rheology

Microcalorimetry Study of the Adsorption of Asphaltenes and Asphaltene Model Compounds at the Liquid–Solid Surface

“…That is, the acidic group immersed into the aqueous phase and the polyaromatic cores "stacked" orthogonally to the surface. And fourth, as recently shown by Bi et al 52 C5Pe is prone to the formation of heterogeneous interfacial films at the xylenewater interface which leads to stable W/O emulsions. Furthermore, BAM and atomic force microscopy (AFM) images showed that rearrangements and accumulation at the interface lead to the progressive build-up of the layer, generating a mechanically strong film.…”

Pickering/Non‐Pickering Emulsions of Nanostructured Sulfonated Lignin Derivatives

“…where g 0 denotes the interfacial tension of the pristine water/ xylenei nterface (0.04 Nm À1 ) [57] and q is the equilibrium contact angle of the oil/water interface in the presence of SEKL/N-SEKL. Measuring q can help predict the emulsion stability, [12] because the energy of adsorption at the interface based on Equation(1) would be relativelys mall < 10 k B T if the particle is too hydrophilic (q 208)o rt oo hydrophobic (q !…”

Accelerated spreading of inviscid droplets prompted by the yielding of strongly elastic interfacial films

“…n = 0.5, = 0 -115 o 9 n ~ 0.5 then 0.06 < n < 0.1, = 0 - Of particular interest in the current study is the contribution from surface elasticity which can be influenced by surface active species partitioning at the liquid-liquid interface. [31][32][33][34] To the authors' knowledge, interfacial effects on the spreading dynamics of droplets are rarely explored except for surfactant systems, with particular focus given to changes in surface tension. Generally, surfactants reduce the equilibrium three-phase contact angle and increase the solid-liquid contact area.…”