The cooling process effect on the bilayer phase state of the CTAC/cetearyl alcohol/water surfactant gel

Development and Thermophysical Profile of Cetyl Alcohol-in-Water Nanoemulsions for Thermal Management

“…The SDS surfactant proved to be effective for the preparation of various paraffin-inwater emulsions using a solvent-assisted method [33,35,60]. However, when emulsifying n-alkanols such as cetyl or stearyl alcohols in aqueous solutions of SDS or cetyltrimethylammonium chloride (CTAC), the association of the fatty alcohol with those ionic surfactants may lead to the formation of lamellar and vesicular gel networks once samples are cooled down below the melting point of the fatty alcohol [61][62][63][64]. Thus, unlike n-alkanes, the slightly polar head of n-alkanols and their straight carbon chain induce head-to-head and tail-to-tail interactions between these types of surfactants and fatty alcohols, allowing them to be integrated in lamellar-type networks [65].…”

“…Thus, unlike n-alkanes, the slightly polar head of n-alkanols and their straight carbon chain induce head-to-head and tail-to-tail interactions between these types of surfactants and fatty alcohols, allowing them to be integrated in lamellar-type networks [65]. Such multiphase colloidal structures (also called "α-gel") contain bilayers made of hexagonally-packed crystals of surfactants and fatty alcohols, which give rise to a creamy texture of the sample [62], which is uninteresting for heat transfer applications. Those gels, whose main binding forces are electrostatic in nature [61], were not observed for cetyl alcohol-in-water emulsions prepared using nonionic polyoxylated surfactants [66], for example.…”

Vesicle formation of single-tailed amphiphilic alkyltrimethylammonium bromides in water induced by dehydration–rehydration

“…[1][2][3][4][5] The micelle-to-vesicle transition can be induced by the variation of environmental conditions, such as the variation of pH, 6,7 temperature, 8,9 heavy metal ions, 10 and salinity, 11 as well as the addition of organic additives. 2,12,13 So far, most of the studies on this subject were performed in aqueous solutions of multi-tailed amphiphiles, [14][15][16] mixed amphiphiles, [17][18][19][20] and amphiphilic polymers. [21][22][23] Simple single-tailed amphiphiles (STAs), such as dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS), are well known to form micelles but not vesicles in aqueous solution without any additives.…”

“…[21][22][23] Simple single-tailed amphiphiles (STAs), such as dodecyltrimethylammonium bromide (DTAB) and sodium dodecyl sulfate (SDS), are well known to form micelles but not vesicles in aqueous solution without any additives. 11,24 For example, Sarabia et al 12 and Colafemmina et al 13 reported the vesicles of the STAs cetyltrimethylammonium bromide (CTAB) and chloride (CTAC) in water, respectively, but formed in the presence of cholesterol and cetearyl alcohol, respectively. However, we recently found that, under the mediation of solid surfaces (such as rough glass surfaces, RGSs), simple STAs can form vesicles from their respective micelle solutions without any additives.…”

Table-top combined scanning X-ray small angle scattering and transmission microscopies of lipid vesicles dispersed in free-standing gel

“…Although less than neutrons, 13 hard X-rays feature sufficiently high penetration depth to study relatively thick samples with no need for specic sample preparation, nonnegligible scattering contrast for light elements, but have on the other hand widespread availability both at synchrotron facilities and in traditional laboratories. Still, SAXS provides important information even in so matter investigation, either by itself or in combination with SANS, 10,13 although studies of complex systems with low scattering contrast such as lipid vesicles have been almost exclusively performed at synchrotron facilities ( 10,(15)(16)(17)(18)(19)(20)(21) among others), except for a few examples, 22 and to the best of our knowledge never as 2D microscopies on thick gel systems. On the other hand, laboratory equipment has been applied to Wide Angle X-ray Scattering studies of lipid vesicles, combined with synchrotron-SAXS/SANS data, 10 or for SAXS studies mainly aimed at deriving the stacking periodicity of packed lipids from Bragg diffraction peaks 11,23 (besides studies of high contrast nanoparticles, e.g.…”