Temperature effect on the microstructure and viscoelastic properties of aqueous micellar systems of sodium <Emphasis Type="Italic">N</Emphasis>-methyl-<Emphasis Type="Italic">N</Emphasis>-oleyl taurate

The quantitative characteristics of the temperature effect on the rheological properties of aqueous solutions of the anionic surfactant sodium methyl oleyl taurate (SMOT) are presented. An increase in the intensity of thermal motion of surfactant molecules on heating from 25 to 45 °С was shown to decrease the average contour length of SMOT micelles from 2 μm to 700 nm. The decrease in the length of cylindrical micelles is probably one of the main reasons for a substantial decrease in the viscosity of micellar solutions of the surfactant with temperature.     

Aggregation behavior of morpholinium surfactants in the presence of organic electrolytes

It was shown that the addition of organic electrolytes to aqueous solutions of morpholinium surfactants facilitates micellization, reduces the micellar surface potential, increases the hydrodynamic diameter of micelles and favors the formation of cylindrical micelles which behave as pseudoplastic fluids. At low shear rates, the viscosity is extremely large and changes insignificantly, and it decreases sharply with increase in shear rate. Significant decrease in viscosity upon the increase in shear deformations indicates the orientation of cylindrical micelles along the direction of the flow with the increase in shear rate.     

Temperature effect on the viscoelastic properties of solutions of cylindrical mixed micelles of zwitterionic and anionic surfactants

The viscoelastic properties of semidilute mixed aqueous solutions of oleyl amidopropylbetaine and sodium dodecylbenzene sulfonate are studied in the temperature range of 20–40°C. It is shown that, at 20°C, the solution viscosity can be as high as 390 (Pa s), which is related to the formation of a network of entanglements of long cylindrical micelles of surfactants. It is revealed that, upon heating, the viscosity and relaxation time of the system decrease, while the contour length of cylindrical micelles decreases consider-ably. It is shown that this susceptibility of viscoelastic surfactant solutions to temperature is due to the low energy of break, which is much lower than the energy of covalent bonds.     

Supramolecular system 4-aza-1-hexadecyl-1-azoniabicyclo[2.2.2]octane bromide—sodium salicylate. Aggregation and rheological properties

The system based on the cationic surfactant 4-aza-1-hexadecyl-1-azoniabicyclo[2.2.2]-octane bromide (DABCO-16) and the organic electrolyte sodium salicylate was studied by tensiometry, conductometry, pH-metry, dynamic and electrophoretic light scattering, and viscosimetry. The critical concentration of micelle formation of DABCO-16 and the electrokinetic potential decrease sharply and the hydrodynamic diameter of the aggregates increases as the concentration of sodium salicylate increases. The rheological properties of the studied solutions are well described by the Maxwell model for a viscoelastic liquid with one relaxation time. Aqueous solutions DABCO-16—sodium salicylate exhibit the properties of an elastic gel and can be used for the formation of compositions with the improved rheological properties.     

Supramolecular Tools to Improve Wound Healing and Antioxidant Properties of Abietic Acid: Biocompatible Microemulsions and Emulgels

Abietic acid, a naturally occurring fir resin compound, that exhibits anti-inflammatory and wound-healing properties, was formulated into biocompatible emulgels based on stable microemulsions with the addition of a carbamate-containing surfactant and Carbopol^® 940 gel. Various microemulsion and emulgel formulations were tested for antioxidant and wound-healing properties. The chemiluminescence method has shown that all compositions containing abietic acid have a high antioxidant activity. Using Strat-M^® skin-modelling membrane, it was found out that emulgels significantly prolong the release of abietic acid. On Wistar rats, it was shown that microemulsions and emulgels containing 0.5% wt. of abietic acid promote the rapid healing of an incised wound and twofold tissue reinforcement compared to the untreated group, as documented by tensiometric wound suture-rupture assay. The high healing-efficiency is associated with a combination of antibacterial activity of the formulation components and the anti-inflammatory action of abietic acid.     

Supramolecular systems based on cationic surfactants: an influence of hydrotropic salts and oppositely charged polyelectrolytes

Russian Chemical Bulletin - For cationic surfactant 4-aza-1-dodecyl-1-azoniabicyclo[2.2.2]octane bromide (DABCO-16), a significant decrease in the critical micelle concentration (CMC) is shown in...