The apparently anomalous effects of surfactants on interfacial tension in the IBA/water system near its upper critical solution temperature

Abstract

We studied the effect of anionic, cationic, and nonionic surfactants on the interfacial tension between the two phases of the isobutyric acid/water system using spinning drop tensiometry. It has been found that interfacial tension decreases with increasing concentration of the surfactant in the case of sodium dodecyl sulfate (SDS) and of dodecyltrimethylammonium chloride (DTAC). However, in the case of Triton X-100 an increase of surfactant concentration leads to an increase of the interfacial tension. Such results are consistent with the upper critical solution temperature (UCST) in the presence of these surfactants: the UCST decreases with increasing SDS and DTAC concentrations while it increases in the case of Triton X-100. This apparently anomalous effect has been explained by considering the molecular structure of Triton X-100, which possesses a short polymeric chain that promotes its partitioning toward one of the two phases making them less compatible and thus raises the UCST and the interfacial tension

Impact of Cross-Linked Chitosan Sublayer Structure on the Performance of TFC FO PAN Nanofiber Membranes

“…50 They can lower the interfacial tension due to their amphiphilic nature. 51 Therefore, we believe that the use of SDBS can improve the wettability of the support, promote monomer migration to the interface region, and enhance the efficiency of the polymerization. 52 First, the side of the modified nanofiber mats was contacted by the MPD solution for 300 s. Excess MPD solution was removed from the support surface using an air knife.…”

“…Sodium dodecyl benzenesulfonate (SDBS), like sodium dodecyl sulfate, is a common type of surfactant . They can lower the interfacial tension due to their amphiphilic nature . Therefore, we believe that the use of SDBS can improve the wettability of the support, promote monomer migration to the interface region, and enhance the efficiency of the polymerization .…”

Spinning Drop Dynamics in Miscible and Immiscible Environments

“…By measuring the drop radius and using Vonnegut’s formula (see below), he inferred the effective (transient) interfacial tension between the fluids. Similar measurements were performed by J. Pojman and co-workers, − who investigated the existence of an effective interfacial tension (EIT) between miscible fluids and discussed its importance, using (i) mixtures of Isobutyric acid and water close to their critical point and (ii) dodecyl acrylate drops in poly­(dodecyl acrylate). They concluded that capillary forces are at work at the boundary between these fluids and quantified the EIT, again using Vonnegut’s theory.…”