Rheology and nuclear magnetic resonance measurements under shear of sodium dodecyl sulfate/decanol/water nematics

Thiele, Thomas; Berret, Jean‐François; Müller, Stefan; Schmidt, Claudia

doi:10.1122/1.1332387

Cited by 27 publications

(31 citation statements)

References 28 publications

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“…For rodlike nematics this angle is usually small, typically (Ternet et al 1999) θ < 10 • , while for disk-like nematics (Chan and Terentjev 2005) θ ≈ 90 • . Moreover, rheological and NMR investigations either in the N C or the N D phases of a lyotropic system close to ours (Thiele et al 2001) concluded that they belong to the flow-aligning class of nematics.…”

Section: Tumbling and Flow Aligning Nematicsmentioning

confidence: 75%

Shear viscosity and rheology of ternary and quaternary lyotropic liquid crystals in discotic and calamitic nematic phases

et al. 2015

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We report rheological studies of micellar nematic phases of potassium laurate/ decanol/ water mixtures with and without addition of salt (K 2 SO 4 ) at a fixed temperature of 20 • C. Using a cone-plate rheometer, we verified that the ternary mixture (i.e., without salt) exhibiting the discotic (N D ) nematic phase showed only a slight pseudo-plastic (or shear-thinning) behavior. In contrast, a pronounced pseudoplastic effect was observed in the N D phase of the quaternary samples. On the other hand, all the N C samples (salted or unsalted) showed a quasi-Newtonian behavior. In addition, we have made viscosity measurements using a (variation of a) rotating Couette flow viscometer. Finally, we also performed density measurements, using a density cell attached to the viscometer. Our results showed a contrasting behavior between the two types of nematic phases in two aspects. Firstly, regarding the ternary samples only, the apparent viscosity η at moderate shear rates was lower in the N C than in the N D phase. The second aspect, regarding both ternary and quaternary samples, is that η in the N D phase dramatically increased as the salt concentration increased, while in the N C phase η was quite insensitive to the addition of salt. In order to analyse the results, we have used two different theoretical frameworks, namely the nematodynamics in the first aspect and the classical theory of electrolyte solutions in the second one.

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Section: Tumbling and Flow Aligning Nematicsmentioning

confidence: 75%

Shear viscosity and rheology of ternary and quaternary lyotropic liquid crystals in discotic and calamitic nematic phases

et al. 2015

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“…Three ternary systems are presented: cetylpyridinium chloride-hexanol-water (at 0.2 M NaCl) [52,119,121], cetylpyridinium chloride-sodium salicylate-water (at 0.5 M NaCl) [122] and Figure 6. Phase diagrams of four wormlike micellar systems: (a) cetylpyridinium chloride, hexanol and water (0.2 M NaCl) [121]; (b) Cetylpyridinium chloride, sodium salicylate and water (0.5 M NaCl) [122]; (c) sodium dodecylsulfate, decanol and water [49,50,120]; (d) cetyltrimethylammonium bromide and water [30,124]. For the diagrams (a), (b) and (c), the cosurfactant concentration is in the ordinate.…”

Section: Phase Behaviormentioning

confidence: 99%

“…Should this splitting be zero, the phase is disordered; should it be non-zero, the phase is nematic. The splitting is actually due to the fact that in an oriented nematic of micelles, the D 2 O molecules of the solvent inherit the alignment of the cylindrical structures [50]. The NMR technique allows measurement of velocity fields and spectral splitting with a spatial resolution on the order of 10-50 μm and needs, in general, long acquisition times.…”

Section: Nuclear Magnetic Resonance Under Shearmentioning

confidence: 99%

“…where the co-surfactant is a short alcohol chain. Classical examples are the ternary systems, sodium alkylsulfatedecanol-water (SdS-Dec [44][45][46][47] and SDS-Dec [48][49][50], see Table 1) and cetylpyridinium chloride-hexanol-brine (CPCl-Hex) [51][52][53][54][55]. In these systems, the ratio between the alcohol and surfactant concentrations controls the polymorphism of the self-assembly.…”

Section: Physical Chemistry Of Wormlike Micelles and Related Systemsmentioning

confidence: 99%

“…Copyright (1994) EDP Sciences.) sodium dodecyl sulfate-decanol-water [49,50,120]. In Figure 6d, the binary system cetyltrimethylammonium bromide-water is shown and the phases are displayed in a temperature-concentration diagram [30,117,123].…”

Section: Phase Behaviormentioning

confidence: 99%

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Rheology of Wormlike Micelles: Equilibrium Properties and Shear Banding Transitions

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We review the experimental and theoretical results obtained during the past decade on the structure and rheology of wormlike micellar solutions. We focus on the linear and nonlinear viscoelasticity and emphasize the analogies with polymers. Based on a comprehensive survey of surfactant systems, the present study shows the existence of standard rheological behaviors for semidilute and concentrated solutions. One feature of this behavior is a shear banding transition associated with a stress plateau in the nonlinear mechanical response. For concentrated solutions, we show that in the plateau region the shear bands are isotropic and nematic.

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Director Orientation of Nematic Side‐Chain Liquid Crystalline Polymers Under Shear Flow: Comparison of a Flow‐Aligning and a Non‐Flow‐Aligning Polysiloxane

Siebert

Quijada‐Garrido

Vermant

et al. 2007

Macro Chemistry & Physics

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The flow behavior and phase structure of two side‐chain liquid‐crystalline polysiloxanes with the same mesogens but different spacers of either four (PSi4) or six (PSi6) methylene groups are studied in the nematic phase by 2H NMR, polarization microscopy, and scattering of light, neutrons, and X‐rays. PSi4 is flow‐aligning, forming a monodomain with the director close to the flow direction, whereas PSi6 is non‐flow‐aligning showing a polydomain structure with a preferred director orientation corresponding to the log‐rolling state. The flow behavior of PSi6 is related to the presence of strong smectic clusters. The director tilt in the smectic clusters of both polymers is reported.magnified image

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Rheology and nuclear magnetic resonance measurements under shear of sodium dodecyl sulfate/decanol/water nematics

Cited by 27 publications

References 28 publications

Shear viscosity and rheology of ternary and quaternary lyotropic liquid crystals in discotic and calamitic nematic phases

Shear viscosity and rheology of ternary and quaternary lyotropic liquid crystals in discotic and calamitic nematic phases

Rheology of Wormlike Micelles: Equilibrium Properties and Shear Banding Transitions

Director Orientation of Nematic Side‐Chain Liquid Crystalline Polymers Under Shear Flow: Comparison of a Flow‐Aligning and a Non‐Flow‐Aligning Polysiloxane

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