Shear-Induced Transitions and Instabilities in Surfactant Wormlike Micelles

Lerouge, Sandra; Berret, Jean‐François

doi:10.1007/12_2009_13

Cited by 147 publications

(172 citation statements)

References 321 publications

(908 reference statements)

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“…The complex viscosity modulus was adjusted using ( ) = 1 + , where = denotes the static viscosity. At T = 27 °C, the viscoelastic parameters are = 7.1 ± 0.1 Pa, = 0.14 ± 0.01 s and = 1.0 ± 0.1 Pa s. These results confirm those published for the first time on the same system two decades ago [39,40,42].…”

Section: -Micro-rheology Of Wormlike Micellessupporting

confidence: 88%

Magnetic wire-based sensors for the microrheology of complex fluids

et al. 2013

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Abstract:We propose a simple µ-rheology technique to evaluate the viscoelastic properties of complex fluids. The method is based on the use of magnetic wires of a few microns in length submitted to a rotational magnetic field. In this work, the method is implemented on a surfactant wormlike micellar solution that behaves as an ideal Maxwell fluid. With increasing frequency, the wires undergo a transition between a steady and a hindered rotation regime. The study shows that the average rotational velocity and the amplitudes of the oscillations obey scaling laws with well-defined exponents. From a comparison between model predictions and experiments, the rheological parameters of the fluid are determined. -IntroductionRheology is the study of flow and deformation of fluids when they are submitted to mechanical stresses. Conventional rheometers determine the relationship between strain and stress in steady or oscillating flow on samples of a few milliliters. µ-rheology in contrast studies the motion of micron-size probe particles that are thermally fluctuating via the interactions with a surrounding medium, or particles that are forced by an external field. In the first case, the µ-rheology is said to be passive, in the second active. In both cases, the motion of the probes is related by the mechanical properties of the medium. Fluids produced in small quantities, e.g. costly protein dispersion or fluids confined in small volumes down to 1 picoliter, such as living cells can only be examined by this technique. With the development of microfluidics systems in the last decade [1], rapid advances were made in the field of µ-rheology. Standard experimental protocols and data treatment softwares are now available and implemented on a regular and controlled basis [2][3][4][5][6][7]. The correspondence between µ-and macro-rheology is nowadays well established. In µ-rheology, the objective is to translate the motion of a probe particle into the relevant rheological

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Section: -Micro-rheology Of Wormlike Micellessupporting

confidence: 88%

Magnetic wire-based sensors for the microrheology of complex fluids

et al. 2013

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“…The relaxation time of the SIS was found to range from several seconds to a couple of hours (26). Similarly, others observed birefringent SIS formation in a solution of surfactant and salt under shear and subsequent disappearance of the birefringent structures after the flow was stopped (24,37). Based on time-dependent SALS studies under a simple shear flow, Kadoma and van Egmond (12) suggested that CTAB/NaSal-based (0.03/ 0.24 M) SISs consist of highly elongated and locally concentrated micellar strings.…”

Section: Flow-induced Structuresmentioning

confidence: 62%

“…Based on time-dependent SALS studies under a simple shear flow, Kadoma and van Egmond (12) suggested that CTAB/NaSal-based (0.03/ 0.24 M) SISs consist of highly elongated and locally concentrated micellar strings. The SIS has since been widely studied using birefringence, light scattering, neutron scattering, X-ray scattering, and NMR (21,24).…”

Section: Flow-induced Structuresmentioning

confidence: 99%

Microstructure and rheology of a flow-induced structured phase in wormlike micellar solutions

Cardiel

Dohnálková

Dubash

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Surfactant molecules can self-assemble into various morphologies under proper combinations of ionic strength, temperature, and flow conditions. At equilibrium, wormlike micelles can transition from entangled to branched and multiconnected structures with increasing salt concentration. Under certain flow conditions, micellar structural transitions follow different trajectories. In this work, we consider the flow of two semidilute wormlike micellar solutions through microposts, focusing on their microstructural and rheological evolutions. Both solutions contain cetyltrimethylammonium bromide and sodium salicylate. One is weakly viscoelastic and shear thickening, whereas the other is strongly viscoelastic and shear thinning. When subjected to strain rates of ∼10 3 s −1 and strains of ∼10 3 , we observe the formation of a stable flow-induced structured phase (FISP), with entangled, branched, and multiconnected micellar bundles, as evidenced by electron microscopy. The high stretching and flow alignment in the microposts enhance the flexibility and lower the bending modulus of the wormlike micelles. As flexible micelles flow through the microposts, it becomes energetically favorable to minimize the number of end caps while concurrently promoting the formation of cross-links. The presence of spatial confinement and extensional flow also enhances entropic fluctuations, lowering the energy barrier between states, thus increasing transition frequencies between states and enabling FISP formation. Whereas the rheological properties (zero-shear viscosity, plateau modulus, and stress relaxation time) of the shear-thickening precursor are smaller than those of the FISP, those of the shear-thinning precursor are several times larger than those of the FISP. This rheological property variation stems from differences in the structural evolution from the precursor to the FISP. microfluidics | microrheology | mesh size S urfactant molecules in aqueous solutions can self-assemble into different structures, such as spherical micelles, cylindrical micelles, lamellar phases, and vesicles (1). The morphology of these self-assembled structures is influenced by surfactant concentration, temperature, external additives (e.g., cosurfactants or salts), and flow conditions. Cylindrical micelles in the presence of inorganic or organic salts can self-assemble into large, flexible, and elongated wormlike micelles that exhibit viscoelastic properties (2-4). The ionic strength of the salt screens the electrostatic repulsions between the charged surfactant head groups, promoting cylindrical micellar growth (1-3). At higher salt concentrations, the entangled linear micelles can transition to branched and multiconnected micellar networks, as evidenced by rheological measurements, light scattering techniques, and electron microcopy (EM) imaging (5-18). Additionally, wormlike micellar solutions are known to exhibit a variety of interesting phenomena, some of which are shear banding (19-21), shear thickening (22, 23), shear-induced transitions and insta...

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“…This scenario has been confirmed experimentally with various techniques like pure viscom-etry, velocimetry, birefringence, etc. (see [13] and Ref. therein) and we shall highlight typical observations in the first section of the present paper.…”

Section: Introductionmentioning

confidence: 66%

Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

et al. 2012

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In the past twenty years, shear-banding flows have been probed by various techniques, such as rheometry, velocimetry and flow birefringence. In micellar solutions, many of the data collected exhibit unexplained spatiotemporal fluctuations. Recently, it has been suggested that those fluctuations originate from a purely elastic instability of the shear-banding flow. In cylindrical Couette geometry, the instability is reminiscent of the Taylor-like instability observed in viscoelastic polymer solutions. The criterion for purely elastic Taylor-Couette instability adapted to shear-banding flows suggested three categories of shear-banding depending on their stability. In the present study, we report on a large set of experimental data which demonstrates the existence of the three categories of shear-banding flows in various surfactant solutions. Consistent with theoretical predictions, increases in the surfactant concentration or in the curvature of the geometry destabilize the flow, whereas an increase in temperature stabilizes the flow. But experiments also exhibit some interesting behaviors going beyond the purely elastic instability criterion.

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Shear-Induced Transitions and Instabilities in Surfactant Wormlike Micelles

Cited by 147 publications

References 321 publications

Magnetic wire-based sensors for the microrheology of complex fluids

Magnetic wire-based sensors for the microrheology of complex fluids

Microstructure and rheology of a flow-induced structured phase in wormlike micellar solutions

Interplay between elastic instabilities and shear-banding: three categories of Taylor–Couette flows and beyond

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