Aqueous two-phase systems of cetyltrimethylammonium bromide and sodium dodecyl sulfonate mixtures without and with potassium chloride added

Role of matching water affinities between oppositely charged headgroups in the rheological properties of aqueous mixed cationic/anionic surfactant systems

“…The phase behaviors of this system are similar to those of 0.10 mol kg −1 AS/CTAB/H 2 O system [47], seven phase regions can be distinguished: in the region with excess CTAB or SL, with the gradual addition of the oppositely charged ionic surfactant into CTAB solution or SL solution, isotropic single-phase systems, aqueous two-phase systems and liquid crystalline systems form in sequence, and finally heterogeneous systems containing more or less precipitate or floc form near equimolar composition. The isotropic single-phase systems with different MR SL/(CTAB+SL) were prepared, and their steady shear viscosity curves as functions of shear rate and Á 0 curves as functions of MR SL/(CTAB+SL) at 308.15 K are shown in Fig.…”

Two-phase aqueous systems of cetyltrimethylammonium bromide/sodium dodecyl sulfate with and without polyethylene glycol

“…The phase behavior of cationic-anionic surfactant aqueous mixture is quite different from that of common aqueous solutions of surfactants and polymers. Usually, the phase diagram of the traditional cationic-anionic surfactant system can be distinguished into seven regions including two aqueous two-phase regions ATPS-A (anionic surfactant is in excess), and ATPS-C (cationic surfactant is in excess), two liquid crystal regions, two transparent homogeneous solution regions as well as a lightly bluish or turbid liquid phase, or a region of precipitate coexisting with liquid [19]. During the experiments we found that the addition of PEG changes the phase behavior of mixed solution dramatically.…”

“…Many studies have shown that almost all aqueous cationic and anionic surfactants can form one or two narrow ATPS regions above critical micelle concentrations (CMC) of mixed solutions [11][12][13][14][15][16][17][18][19]. In these ATPS, both phases are dilute and the surfactant in one phase is significantly different from that in the other.…”

Hexafluoroisopropanol-induced coacervation in aqueous mixed systems of cationic and anionic surfactants for the extraction of sulfonamides in water samples

“…Though inorganic salts [17][18][19][20][21] and hydrocarbon alcohols [22][23][24][25] can induce coacervation in mixtures of catanionic surfactants with long carbon chain (total carbon ≥24), the coacervate formation and aqueous two-phase separation occur only over a narrow range of molar ratios and concentrations of cationic and anionic surfactants.…”

“…It has been reported that inorganic salts (e.g., NaCl, KCl, NaBr, etc.) [17][18][19][20][21] and hydrocarbon alcohols (e.g., ethanol, propanol, octanol, etc.) [22][23][24][25] can induce coacervation in aqueous mixed systems of cationic and anionic surfactants due to the decrease of attraction/repulsion between surfactant headgroups caused by the electrostatic screening effect of inorganic salts [19] and the interactions of alcohol hydroxyl group (with ionization and H-bond donor feature) with surfactant polar headgroups [22,24].…”