Rheology of Cetyltrimethylammonium Tosylate-Water System. 1. Relation to Phase Behavior

Soltero, J. F. A.; Puig, J. E.; Manero, Ο.; Schulz, Pablo C.

doi:10.1021/la00009a013

Cited by 109 publications

(141 citation statements)

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“…This value is much lower of that measured in the same dynamic conditions for worm-like micellar solution of cetyltrimethylammonium tosylate (CTAT)/water system (i.e. G 0 ≈ 400 Pa and c = 23 wt.% CTAT) at 30 • C [20]. In the light of these facts, one can distinguish two main structural regimes within the composition range of the micellar solution.…”

Section: Micellar Phasementioning

confidence: 69%

Shear rheology and phase behaviour of sodium oleate/water mixtures

Antunes

Coppola

Gaudio

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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The knowledge of structural and dynamical properties in binary sodium oleate (NaO)/water mixtures represents a first step for studying new biocompatible structures. In addition, a deeper understanding of their flow behaviour is crucial to control their mechanical properties. The purpose of this investigation was to revisit the binary NaO/water phase diagram through a combined effort of shear-rheology, NMR-diffusometry, optical polarizing microscopy and differential scanning calorimetry. The preparation of NaO/water mixtures in this work fitted with the interesting regions of the phase diagrams where most of the new systems will be prepared (i.e. from 0.01 to 30 wt.% NaO and within the temperature range 5-70 • C).Steady shear and linear viscoelastic experiments were accurately performed and the relationship between phase morphology and rheological properties was also studied. Regarding the mixtures at low surfactant concentrations, the shear flow showed: (1) a structural evolution into the liquid micellar phase (L 1 ) as a function of composition and (2) the presence of a viscous micellar region (L * 1 ) induced by temperature and composition changes. NaO/water mixtures with a liquid-crystalline structure (hexagonal H 1 ) were studied by linear shear deformations and paying particular attention to frequency and temperature scans. Viscoelastic spectra of H 1 phase presented a gel-like response which, although not expected, indicated the presence of a stiff liquid-crystalline lattice. Finally, a correlation between rheology and microstructural changes was conducted by the "weak-gel" model.

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Section: Micellar Phasementioning

confidence: 69%

Shear rheology and phase behaviour of sodium oleate/water mixtures

Antunes

Coppola

Gaudio

et al. 2007

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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“…11,26 Moreover, under steady shear, these solutions exhibit shear-banding flow in the concentration range of ca. 0.044 to 0.55 M at 30 C.…”

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confidence: 99%

Effect of ionic strength on rheological behavior of polymer-like cetyltrimethylammonium tosylate micellar solutions

et al. 2011

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The influence of ionic strength on the rheological properties of polymer-like aqueous micellar solutions of cetyltrimethylammonium tosylate (CTAT) containing different salts (KCl, KBr, (COONa) 2 , K 2 SO 4 or K 3 PO 4 ) is investigated. The rheological behavior of the solutions is analyzed above the concentration where a micellar entanglement network is formed, varying surfactant and salt concentration, salt counterion valency and temperature. A master curve of the linear viscoelastic properties is obtained by multiple superposition of time, temperature, salt type, and surfactant and salt concentration. Application of the existent kinetic theory provides information suggesting that the micellar solutions are in the fast breaking regime (i.e., the relaxation is kinetically controlled) regardless of salt type and concentration. Moreover, these solutions exhibit shear-banding flow with a reduced stress plateau (s/G 0 , being s and G 0 the shear stress and the plateau modulus, respectively) that increases with salt content and counterion valency. The zero-shear viscosity (h 0 ) and the main relaxation time (s C ) diminish with increasing salt content according to a step-like function, in which the number of steps increases with the salt counterion valence. In contrast, G 0 only increases slightly with increasing salt content for the five salts employed. These results are discussed in terms of ionic strength and screening of the electrostatic-interactions caused by the addition of salt. In addition, it was found that the influence of anions on the viscoelastic properties of the polymer-like micelles follows the Hofmeister series commonly encountered in macromolecular and biological systems. This finding opens a challenge for scientists in the experimental and theoretical fields.

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“…The rheology of CTAT (cetyl trimethylammonium tosilate) has been examined extensively in the linear viscoelastic regime 10 . Above the Kraft temperature of 23 • C and at low concentrations (C < 0.04 wt.%), spherical micellar solutions are formed which exhibit Newtonian flow behaviour.…”

mentioning

confidence: 99%

“…Above the Kraft temperature of 23 • C and at low concentrations (C < 0.04 wt.%), spherical micellar solutions are formed which exhibit Newtonian flow behaviour. At higher surfactant concentrations (0.04 < C < 0.9 wt.%), cylindrical wormlike micelles are formed which get entangled at C > 0.9 wt.% to form clear viscoelastic gels 10 . The purpose of this Letter is to report interesting time-dependence of the shear and normal stresses after subjecting the system to a step shear rate lying in the plateau region.…”

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confidence: 99%

Observation of Chaotic Dynamics in Dilute Sheared Aqueous Solutions of CTAT

2000

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The nonlinear flow behaviour of a viscoelastic gel formed due to entangled, cylindrical micelles in aqueous solutions of the surfactant CTAT has been studied. On subjecting the system to a step shear rate lying above a certain value, the shear and normal stresses show interesting time dependent behaviour. The analysis of the measured time series shows the existence of a finite correlation dimension and a positive Lyapunov exponent, unambiguously implying that the dynamics can be described by that of a dynamical system with a strange attractor whose dimension increases with the increase in shear rate.PACS numbers: 83.50. By, 83.50.Gd, 83.50.Ws, 82.70.Gg. Systems of giant wormlike micelles formed in certain surfactant solutions are known to show very unusual nonlinear rheology. In steady shear, the shear stress σ saturates to a constant value while the first normal stress difference increases roughly linearly with shear ratė γ 1,2 . The constitutive model of viscoelastic behaviour of wormlike micellar systems which incorporates reptation and reaction dynamics (breakage and recombination of micelles), predicts a mechanical instability of the shear banding type 3 where bands supporting high shear rates (low viscosity) coexist with regions of lower shear rates (higher viscosity). Flow birefringence 4 and nuclear magnetic resonance velocity imaging 5 have revealed the existence of banded flow in the shear stress plateau. An alternative explanation for the non-monotonicity of the flow curve has also been proposed 6,7 in terms of the coexistence of two thermodynamically stable phases -isotropic and nematic, present in the sheared solution. Berret 6 observed damped, periodic oscillations in the stress relaxation of CPyCl-NaSal solution at a surfactant volume fraction φ of 12% on the application of controlled shear ratesγ. Grand et al 8 have shown the existence of a metastable branch in the flow curve of dilute CPyClNaSal solution supporting stresses higher than that observed in the stress plateau. They have explained their results in terms of shear banding. Previous observations of shear stress fluctuations in CTAB-NaSal solutions have been explained in terms of shear thickening induced by the growth and retraction of shear induced structures 9 .The rheology of CTAT (cetyl trimethylammonium tosilate) has been examined extensively in the linear viscoelastic regime 10 . Above the Kraft temperature of 23 • C and at low concentrations (C < 0.04 wt.%), spherical micellar solutions are formed which exhibit Newtonian flow behaviour. At higher surfactant concentrations (0.04 < C < 0.9 wt.%), cylindrical wormlike micelles are formed which get entangled at C > 0.9 wt.% to form clear viscoelastic gels 10 . The purpose of this Letter is to report interesting time-dependence of the shear and normal stresses after subjecting the system to a step shear rate lying in the plateau region. Our detailed analysis shows unambiguously that the observed dynamics can be described as that of a low dimensional, dynamical system with a strange a...

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Rheology of Cetyltrimethylammonium Tosylate-Water System. 1. Relation to Phase Behavior

Cited by 109 publications

References 1 publication

Shear rheology and phase behaviour of sodium oleate/water mixtures

Shear rheology and phase behaviour of sodium oleate/water mixtures

Effect of ionic strength on rheological behavior of polymer-like cetyltrimethylammonium tosylate micellar solutions

Observation of Chaotic Dynamics in Dilute Sheared Aqueous Solutions of CTAT

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