Shear orientation of a lamellar lyotropic liquid crystal

Läuger, Jörg; Linemann, Reinhard; Richtering, Walter

doi:10.1007/bf00398432

Cited by 31 publications

(34 citation statements)

References 14 publications

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“…This new pattern corresponds to an ordered structure of spherulites as the state previously described but is constituted of much bigger vesicles (around 10 mm T 24.3 ± C). Moreover, even under shear, several orders of diffraction can be observed (up to [3][4]. Contrarily to the previous ordered state, when the shear is stopped the pattern remains [see Fig.…”

Section: Philippe Sierro and Didier Rouxmentioning

confidence: 95%

“…At even higher shear rates, there is a transition between this ordered population of vesicles of size typically 1 mm to another ordered state made of vesicles which are much bigger (from 10 to 50 mm). Recently, it has been shown that the effect of shear on both lyotropic and thermotropic lamellar phases can be described by a shear diagram describing a succession of stationary states of orientations separated by dynamic transitions [1][2][3]. In the first system studied [2], the shear diagram exhibited three different orientation states.…”

Section: Philippe Sierro and Didier Rouxmentioning

confidence: 98%

“…[S0031-9007(97)02380-6] PACS numbers: 64.70. Md, 61.30.Eb, 82.20.Db Recently, it has been shown that the effect of shear on both lyotropic and thermotropic lamellar phases can be described by a shear diagram describing a succession of stationary states of orientations separated by dynamic transitions [1][2][3]. In the first system studied [2], the shear diagram exhibited three different orientation states.…”

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Structure of a Lyotropic Lamellar Phase under Shear

1997

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The effect of shear on a lyotropic lamellar phase is studied by the means of small-angle light scattering and direct microscopic observations. We found a complex behavior that can be described by a shear diagram. This diagram exhibits successively as a function of shear four different steady states. After a transition to a phase of monodisperse multilamellar vesicles with no long-range order there is a transition to the same vesicles exhibiting long-range order. At even higher shear rates, there is a transition between this ordered population of vesicles of size typically 1 mm to another ordered state made of vesicles which are much bigger (from 10 to 50 mm). [S0031-9007(97)02380-6] PACS numbers: 64.70. Md, 61.30.Eb, 82.20.Db Recently, it has been shown that the effect of shear on both lyotropic and thermotropic lamellar phases can be described by a shear diagram describing a succession of stationary states of orientations separated by dynamic transitions [1][2][3]. In the first system studied [2], the shear diagram exhibited three different orientation states. At very low shear, a partially oriented state with the normal to the smectic layers mainly parallel to the shear gradient direction was observed until a transition to a state of monodisperse multilayered vesicles (named spherulites) was observed (around 1 s 21 ). At even higher shear rate (10 1000 s 21 depending upon the lyotropic sample) another transition was observed between the state of vesicles to another oriented state with no defect in the direction of the flow but some defects remaining in the vortex direction. The connection between the rheological properties of the lamellar phase and the shear diagram has been made [4].More recently while studying a different system, another type of transition has been observed. In the multilayered vesicle state, a layering transition has been observed [5] similar to the shear ordering transition observed in colloids [6]. Indeed, in increasing the shear rate, the multilayered vesicle state that does not exhibit any long-range order between the vesicles spontaneously orders under shear to show a long-range order of layers of vesicles sliding on each other.We report here a more complex behavior observed on a lyotropic lamellar phase. In addition to the transitions previously described as a function of shear, this system exhibits a new transition between two states of ordered multilayered vesicles. These two states can be easily differentiated by the vesicle size, and the transition between these two states is observed as a jump from small to big vesicles when either the shear rate or the temperature is increased. This transition which is in general discontinuous becomes continuous above a critical temperature. The shear diagram of this system is established.The system studied is a quaternary lyotropic lamellar phase which phase diagram has already been published [7]. It is composed of water, sodium dodecyl sulfate (SDS), octanol, and sodium chloride. One unique sample has been studied whose composition is, respe...

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Section: Philippe Sierro and Didier Rouxmentioning

confidence: 95%

Section: Philippe Sierro and Didier Rouxmentioning

confidence: 98%

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confidence: 99%

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Structure of a Lyotropic Lamellar Phase under Shear

1997

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“…Lamellar phases of aqueous mixtures solutions of amphiphiles instead of the molecules themof a nonionic surfactant have been investigated by this group selves. As a function of concentration and temperature, difand different behavior was found at high and intermediate ferent anisotropic aggregates and hence different phases can surfactant concentration (36,37). be formed.…”

Section: Introductionmentioning

confidence: 99%

Rheo-small-Angle-Light-Scattering Investigation of Shear-Induced Structural Changes in a Lyotropic Lamellar Phase

Läuger

Weigel

Berger

et al. 1996

Journal of Colloid and Interface Science

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“…Shearing the sample leads to the fragmentation of elongated species or ordered domains, and thus to a lower viscosity. [23][24][25][26] Indeed, optical anisotropy indicating liquid crystalline behavior was observed by polarized optical microscopy for the LCA(PEG 4 ) 2 sample ( Figure S3 in Supporting Information). Fibrillar structures shown by micrographs are similar to those of presented in literature for bile salts, assigned by La Mesa and coworkers to lyotropic liquid crystallinity [27] Shear-thinning character has been described for alkaline suspensions of sodium lithocholate, arising from the orientation of entangled nanotubes or fibers.…”

Section: Aggregation Of Lca(eg 4 ) 2 At High Concentrationsmentioning

confidence: 91%

Thermosensitivity of Bile Acid‐Based Oligo(ethylene glycol) Stars in Aqueous Solutions

Strandman

Dévédec

Zhu

2011

Macromol. Rapid Commun.

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Amphiphilic star-shaped oligo(ethylene glycol)s with a hydrophobic bile acid core and varying number of hydrophilic arms have been made. Their thermal behavior in aqueous solutions depends on the number rather than the length of the arms. The two-armed lithocholate derivative showed the strongest tendency for association and exhibited the lowest cloud point (79 °C) of the oligomers made, as well as another phase separation at a lower temperature (31 °C). The "double thermosensitivity" arising both from the salt-dependent LCST of the oligo(ethylene glycol) segments and the temperature-responsive self-assembly of amphiphilic bile acid derivative provides an interesting path in the design of bile acid-based smart materials.

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Shear orientation of a lamellar lyotropic liquid crystal

Cited by 31 publications

References 14 publications

Structure of a Lyotropic Lamellar Phase under Shear

Structure of a Lyotropic Lamellar Phase under Shear

Rheo-small-Angle-Light-Scattering Investigation of Shear-Induced Structural Changes in a Lyotropic Lamellar Phase

Thermosensitivity of Bile Acid‐Based Oligo(ethylene glycol) Stars in Aqueous Solutions

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