Phase and Rheological Behavior of Cetyldimethylbenzylammonium Salicylate (CDBAS) and Water

Abstract

The temperature-composition phase diagram in the diluted region of the cationic surfactant cetyldimethylbenzylammonium salicylate/water system was studied with a battery of techniques. The Krafft temperature (T k = 33 ± 1°C) was measured by differential scanning calorimetry, polarizing microscopy, conductimetry, viscosimetry, and rheometry. The critical vesicle concentration (cvc, *0.002 wt%) and a vesicle-micellar transition (cvm, *0.005 wt%) was detected at a temperature of 35°C. Below T k and concentrations B2 wt%, a transparent solution is formed (I). Above 2-8.5 wt%, a lamellar (L 1 ) phase forms. At higher concentrations and up to 12 wt%, a second lamellar phase (L 2 ) is detected. From 12.4 to 15.5 wt%, an emulsion phase (E) is formed. Rheological dynamic measurements for the I phase indicate that the system exhibits a predominantly viscous behavior (G 0 \ G 00 ) for concentrations lower than the overlap or entanglement concentration (C e , *0.75 wt%). At higher concentrations, wormlike micelles form and the elastic behavior predominates (G 0 [ G 00 ). The elastic (G 0 ) modulus collapses in a concentration-time master curve in the whole reduced frequencies range xs c examined, whereas the viscous modulus (G 00 ) collapses only at reduced frequencies lower than 0.1. Reduced stress plotted as a function of the reduced shear rate yields a good superposition of the curves at the different concentrations up to the onset of the non-linear behavior.

On the shear thickening behavior of micellar aqueous solutions of cetyltrimethylammonium fluorobenzoates: Effect of the fluor position

“…Hydrotropes cannot form organized self-associated structures, such as micelles, because their hydrophobicity is lower than that of surfactants; however, they decrease substantially the critical micellar concentration (cmc) and induce the transition from spherical to rod micelles (cmc 2 ) as well as wormlike micelles formation at lower surfactant concentrations. This ability typically increases when the hydrotrope molecules have aromatic structures [3][4][5][6][7][8][9][10][11][12][13][14][15]. For instance, the addition of hydrotrope salts such as 2-hydroxybenzoate to cetyltrimethylammonium bromide (CTAB) solutions induces the formation of wormlike micelles at very low concentration whereas the addition of 3-and 4-hydroxybenzoate counterions does not.…”

Rheological and Microstructural Behavior of a Model Concentrated Fabric Softener

“…This research concluded that micellar solutions composed of cationic surfactants at concentrations close to the CMC show Newtonian behavior [4]. However, with increasing surfactant concentration, distinct phase structures with viscoelastic properties are observed, indicating network formation [17]. The rheological and mechanical properties of surfactant solutions depend on the network which is formed by the self-associating molecules interacting among themselves [1,2].…”

The Effect of Aniline Hydrochloride Hydrotrope on the Phase Behavior of SDS/Water System

“…Hydrotropes can also induce the formation of wormlike (polymer-like) micelles at lower surfactant concentrations. This ability is larger when the hydrotrope counterions possess benzene derivative structures [3][4][5][6][7][8][9][10][11][12]. As an example, when 4-(4CB ? )…”

“…Electronic supplementary material The online version of this article (doi:10.1007/s11743-017-1934-z) contains supplementary material, which is available to authorized users. 4-hydroxybenzoate (4HB ? ) hydrotropic counterions are incorporated, wormlike micelles are not formed [13][14][15][16].…”

“…In fact, the growth of the aggregates is influenced mainly by the localization and orientation of the substituent in aromatic hydrotropic counterions [14][15][16][17]. Moreover, variations in surfactant and counterion concentrations [15,16,18], head group area, hydrocarbon volume, critical chain length tail [4,11,17], and electrostatic interactions between the head groups [12,17,19,20] may modify the morphology of the micelles, i.e., size and shape. For some monovalent counterions, there is a selectivity that follows the Hofmeister series [21].…”