Dissolution of anionic surfactant mesophases

Abstract

Linear and circular solvent penetration experiments are used to study the dissolution of anionic SLES surfactant mesophases in water. We show that a lamellar (L) phase in contact with water will transit through a series of cubic, hexagonal, and micellar phase bands with sharp interfaces identified from their optical textures. In both linear and circular geometries, the kinetics of front propagation and eventual dissolution are well described by diffusive penetration of water, and a simple model applies to both geometries, with a different effective diffusion coefficient for water D as the only fitting parameter. Finally, we show a surprising variation of dissolution rates with initial surfactant concentration that can be well explained by assuming that the driving force for solvent penetration is the osmotic pressure difference between neat water and the aqueous fraction of the mesophase that is highly concentrated in surfactant counterions.

Studying the Structure of Sodium Lauryl Ether Sulfate Solutions Using Dissipative Particle Dynamics

“…In this work, we have established the phase diagram at room temperature for pure SLE n S surfactants in the range n = 0–3. We study the whole of the phase diagram across a large concentration range, where we find good agreement with experimental phase diagrams for AES, SDS, and SLE 3 S . In general, the correct type of phase is identified as a function of concentration and ethoxylation, and phase boundary locations are in good agreement with experimental data.…”

“…When the concentration of surfactant molecules in solution is above a critical concentration, the molecules will self-assemble into phases, a behavior which is driven by their amphiphilic nature. The particular arrangement of molecules taken is dependent on conditions such as the temperature, concentration, − and surfactant type . Phases include micellar, lamellar, bicontinuous cubic, and hexagonal structures. − In general, phases formed by ionic surfactants tend to be mostly dependent on variation of concentration, while for many nonionic surfactants, temperature is the most important variable .…”

“…The particular arrangement of molecules taken is dependent on conditions such as the temperature, concentration, − and surfactant type . Phases include micellar, lamellar, bicontinuous cubic, and hexagonal structures. − In general, phases formed by ionic surfactants tend to be mostly dependent on variation of concentration, while for many nonionic surfactants, temperature is the most important variable . In this work, we study the formation of micellar phases and mesophases by anionic surfactants, where the relationship between the phase behavior and concentration is of particular interest, due to the widely differing properties that different phases possess.…”

The curious case of SDS self-assembly in glycerol: Formation of a lamellar gel

“…Surfactant/lipid self-assembly in aqueous media is well understood [6][7][8][9][10][11][12][13][14][15] , with the hydrophobic effect identified as the driving force 16,17 and the aggregate shape well predicted by the packing parameter [18][19][20][21] . At higher surfactant or lipid concentrations, complex mesophases can form and this phase behaviour depends on the amphiphile concentration, pressure, and temperature.…”

Ionotropic Gelation Fronts in Sodium Carboxymethyl Cellulose for Hydrogel Particle Formation

“…The gel front propagation experiments were performed in a linear geometry, following our previous work in surfactant mesophase dissolution kinetics [ 62 ], using either fabricated microchannels or employing borosilicate glass capillaries (CM Scientific, Silsden, UK). Microchannels for front propagation experiments were fabricated by closed-face frontal photo-polymerization (FPP) of a thiol–ene copolymer (NOA 81, Norland Adhesives, Cranbury, NJ, USA) sandwiched between glass microscope slides of 75 × 25 mm dimensions (VWR, Lutterworth, UK), following previously published procedures [ 63 , 64 , 65 , 66 ].…”