Journal of Surfactants and Detergents

A biantennary surfactant based on a synthetic C₁₆‐maltoside was chosen to prepare vesicles for a potential vesicular drug delivery system. The synthesis comprised of three stages: Initial synthesis of β‐d‐maltose octaacetate was followed by glycosidation of 2‐hexyl‐decanol and final glycolipid deacetylation. Both α‐ and β‐anomers were prepared and their anomeric purity was evaluated by ¹H NMR. Owing to the low water solubility of the glycolipid, addition of ionic co‐surfactants was believed to promote the surfactant distribution, thus leading to smaller and more uniform vesicles. The assembly behavior of the surfactant systems was studied by contact penetration under an optical polarizing microscope, while interfacial properties were determined by surface tension measurements. Vesicles were prepared by injection of an ethanolic solution into bulk water and investigated by dynamic light scattering and field emission scanning electron microscopy. Contact of the surfactant mixtures with water indicated a high tendency to exhibit the lamellar phase and confirmed the expected low molecular solubility. These findings suggest a potential of the surfactant to form stable vesicles. Injection of an ethanolic surfactant solution into bulk water gave sub‐micrometer sized vesicles with a narrow size distribution. Application of ionic co‐surfactants reduced the vesicle size. In particular ∼20 % of anionic SDS proved highly effective, lowering the vesicle size by nearly one decade, thus accessing nano‐sized vesicles. Encapsulation of a water‐soluble drug was achieved in a 76 ± 10 % efficiency.

Distribution of fabric softeners on cotton terry cloth was studied using scanning electron microscopy and energy dispersive X‐ray analysis. The unsaturated groups in the quaternary fabric softeners were tagged with osmium tetroxide to provide contrast in the microscopy. Longitudinal specimens showed the fabric softeners distributed over the cotton fiber surfaces with more in the crenulation of the fiber. Cross sectional specimens revealed that the fabric softener was distributed throughout the cotton fibers with higher concentrations of fabric softener observed in the lumen and crenulation than in the secondary wall and non‐crenulated fiber surface. This distribution of fabric softener is consistent with deposition on both external fiber surfaces and internal fibril surfaces. The deposition and final surface coverage is strongly dependent on the pH value of the washing medium. Repeated treatment cycles with fabric softener using a higher pH washing media resulted in higher concentrations of fabric softener on and within the cotton fibers. Neutral or lower pH washing media resulted in a somewhat constant concentration of fabric softener on and with cotton fibers with increased number of treatment cycles. Differences in perception of softness of the treated fabrics are not explained by differences in distribution of the fabric softener; it appear that there is an optimum amount of softener to achieve the desired sensory response and that further deposition build‐up does not increase perception of softness.

A cloud point extraction process using a silicone non‐ionic surfactant to extract selected parabens compounds from water samples was investigated using reversed phase high performance liquid chromatography. The cloud point extraction process, in the presence of β‐cyclodextrin (β‐CD) as a modifier, is a new extraction process which was optimized with five parameters, i.e. salt concentration, pH of the solution, temperature, surfactant concentration and β‐CD concentration. The developed method with the β‐CD modifier results in an excellent performance on detection of parabens from water samples with limits of detection in the range of 0.017–0.043 μg/L and percentage recoveries from 90.5 to 98.9 %.