Temperature sensitivity of wormlike micelles in poly(oxyethylene) surfactant solution: Importance of hydrophilic-group size

Rheology of branched wormlike micelles

“…The shear rate at which shear-thinning begins is related to the inverse of the relaxation time (see Section 2), which depends on the concentration with a minimum transition rate occurring at the same concentration where there is a maximum in the zero-shear viscosity. Similar dependencies on the onset rate of shearthinning were shown by: Ahmed and Aramaki [39] by controlling the temperature of ChEO m (m = 15 and 30); by Aramaki et al [40] by varying the weight fraction of alcohol in water/C 16 SE/monohydroxy alcohol systems; by Chu et al [28] by altering the total surfactant concentration in EDAS and NaCl mixtures; by Ge et al [37] by altering the ratio of mixed aromatic counterions of NaSal and NaEBS in CTAC cationic surfactant solutions; by Li et al [35] by controlling the temperature in CTAB and AZONa mixtures; by Lu et al [30] by altering the mass fraction of HN in HN/CTAB systems at a fixed temperature; by Sakai et al [44] by varying the HTAB concentration in mixtures of gemini surfactants; by Shrestha et al [45] by varying the C 12 EO 4 concentration in 5 % ChEO 20 / H 2 O mixtures; and by Shrestha et al [49] by varying the C 16 EO 3 concentration for 15 wt.% LAD-TEA/water/C 16 EO 3 systems with fixed KBr content.…”

Thermo-responsive Wormlike Micelles

“…The thermo-viscosifying temperature ranged from 0 to ~40 °C, depending on the surfactant concentration. Compared with C 12 EO 6 WLMs, the thermo-viscosifying range of C 12 EO 8 WLMs was shifted to higher temperatures [32], implying that an increase in PEG chain length can be used to tune the critical responsive temperature, in agreement with the findings by Ahmed and Aramaki discussed above [31]. Utilizing Cryo-TEM observation and light scattering techniques, Talmon et al [33] examined the temperature sensitivity of WLMs formed by a similar polyoxyethylene alkyl ether, C 12 EO 5 .…”

“…2.1d) [35]. Similar to PEG-based macromolecules, these non-ionic wormlike micellar systems also display thermo-viscosifying behaviour [8,14,28,[30][31][32][33][34].…”

“…2.1b) [29,30], polyoxyethylene alkyl ether (C n EO m , Fig. 2.1c) [31][32][33][34], and perfluoroalkyl sulphonamide ethoxylate (C 8 F 17 EO 10 , Fig. 2.1d) [35].…”

“…For WLMs composed of 10 wt% ChEO 20 and 5.7 wt% C-11S, rheological measurements performed over a wide range of temperatures revealed changes in viscosity of various orders of magnitude upon small increases in the temperature. Ahmed and Aramaki [31] investigated the effect of PEG chain length on the temperature sensitivity of ChEO x WLMs, using ChEO 15 and ChEO 30 as a model surfactant and C 12 EO 3 as a cosurfactant. Again, the rheological properties of the worms were found to be highly sensitive to temperature, but largely dependent on the hydrophilic size of the surfactant: the ChEO 30 systems are less temperature sensitive than the ChEO 15 worm systems; that is, the increase of the PEG chain length reduces the thermo-sensitivity of the worms.…”