Shear-Induced Transformations in the Lamellar Phase of Hexaethylene Glycol Monohexadecyl Ether

Penfold, J.; Staples, E.; Lodhi, Aayushi; Tucker, and I.; Tiddy, G. J. T.

doi:10.1021/jp9622851

Cited by 72 publications

(76 citation statements)

References 21 publications

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“…The change in direction of the flow (and consequently the shear gradient) within the beam aperture is estimated to be ~, +10 ° [similar to the angular aperture over which the scattering intensity is normally integrated (Penfold, Staples & Cummins, 1991)] and so does not substantially affect the quality of the data. We have measured the scattering for an isotropic micellar solution (Penfold, Staples, Lodi, Tucker & Tiddy, 1996) (15% C12E12 in D20) through the cell side and centre to normalize approximately the scattering through the cell side for the spatially variable path length through the cell in that geometry. The Couette-cell drive mechanism has been modified to include a 'cam follower' and provide the capability for oscillatory (sinusoidal) flow in addition to steady Couette flow.…”

Section: Methodsmentioning

confidence: 99%

“…The scattering in the orthogonal direction (Qy) is dominated in this case by the defect scattering and results in a correlation peak at a slightly smaller value of Q. The nature of defects in lamellar phases has been discussed in detail elsewhere (Penfold, Staples, Lodi, Tucker & Tiddy, 1996;Funari, Holmes & Tiddy, 1994;Fr6ba & Kalus, 1995) and will not be considered further in this paper.…”

Section: Lamellar Phase Of C16e6mentioning

confidence: 99%

See 1 more Smart Citation

Shear-Induced Structures in Concentrated Surfactant Micellar Phases

Penfold¹,

Staples²,

Tucker³

et al. 1997

J Appl Cryst

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Constant and oscillatory Couette shear flow have been used in combination with small-angle neutron scattering to observe the shear-induced ordering in concentrated surfactant micellar phases. For the lamellar phase of hexaethylene glycol monohexadecyl ether, C16E6, two distinct lamellae orientations have been identified. At low shear gradients the lamellae are ordered parallel to the flow-vorticity plane, whereas at higher shear gradients the lamellae order parallel to the flow-shear gradient plane, corresponding to a rotation through 90 ° of the axis of orientation. At intermediate values of constant shear and for oscillatory shear, both lamellae orientations are simultaneously observed for the first time in a surfactant lamellar phase. For the lamellar phase, a dispersion of the binary surfactant mixtures of dioleyl cationic and 2-ethyl hexaglycerol monoether surfactants, a high degree of alignment, in the direction parallel to the flow-vorticity plane, is observed at zero and low shear. With time, during the application of a shear gradient of 25 s-i, the lamellar phase transforms to a highly ordered solution of monodisperse multilamellar vesicles.

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Section: Methodsmentioning

confidence: 99%

Section: Lamellar Phase Of C16e6mentioning

confidence: 99%

Shear-Induced Structures in Concentrated Surfactant Micellar Phases

Penfold¹,

Staples²,

Tucker³

et al. 1997

J Appl Cryst

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“…Figures 3 and 5a demonstrate that the peak height decreases significantly as the shear rate increases up to 0.1 s )1 where the jumping of the repeat distance does not yet occur. It has been known that the shear flow affects the orientation of lamellae [6][7][8]. If there is alignment, there should be an increase in the peak height in one direction (corresponding to that particular lamellar orientation) on the cost of the two others.…”

Section: Shear Flow and Lamellar Domainsmentioning

confidence: 99%

“…In the past 10 years, effects of shear flow on the structure of the surfactant lamellar phase have been studied extensively by using microscopy, NMR, and various kinds of scattering techniques. After the pioneering work of Roux and coworkers [2][3][4][5] who found the transformation from the lamellar phase to the multilamellar vesicles (onions), various types of shear effects have been reported: change in orientation of membranes [6][7][8], sponge-to-lamellar transformation [9,10], multilamellar-to-unilamellar vesicle transformation [11][12][13], reduction in the spacing [14][15][16][17][18][19], collapse of membranes [20], formation of multilamellar cylinders as intermediate structures between lamellar and onions [21][22][23][24], and formation of Ribbon phase [25]. These effects have been found for the shear rate of 1$5 · 10 3 s )1 .…”

Section: Introductionmentioning

confidence: 99%

Effects of shear flow on structures of lamellar phase in a nonionic surfactant/water system

Kato

Minewaki

Miyazaki

et al. 2004

Mesophases, Polymers, and Particles

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IntroductionStructures of surfactant self-assemblies are often affected by shear flow because their characteristic relaxation time (s) is usually long enough to satisfy the condition _ cs > 1 for the typical shear rate _ c ¼ 10 À2 $ 10 3 s À1 [1]. In the past 10 years, effects of shear flow on the structure of the surfactant lamellar phase have been studied extensively by using microscopy, NMR, and various kinds of scattering techniques. After the pioneering work of Roux and coworkers [2-5] who found the transformation from the lamellar phase to the multilamellar vesicles (onions), various types of shear effects have been reported: change in orientation of membranes [6][7][8], sponge-to-lamellar transformation [9, 10], multilamellar-to-unilamellar vesicle transformation [11][12][13], reduction in the spacing [14][15][16][17][18][19], collapse of membranes [20], formation of multilamellar cylinders as intermediate structures between lamellar and onions [21][22][23][24], and formation of Ribbon phase [25]. These effects have been found for the shear rate of 1$5 · 10 3 s )1 . In our previous studies, on the other hand, attention has been paid to the behaviors at relatively low shear rates, 10 )3 $50 s )1 . At these shear rates, we have measured small-angle neutron scattering (SANS) on the lamellar phase of a nonionic surfactant C 16 H 33 (OC 2 H 4 ) 7 OH (C 16 E 7 )/D 2 O system [15][16][17]26]. This system was chosen because phase behaviors and structures of the micellar and lamellar phases had been studied extensively by us [27][28][29][30]. We have found that the repeat distance (d) decreases significantly (down to about 40% of the initial d value in the extreme case) and discontinuously by shear flow [26]. In the present study, to confirm these findings, we have measured small angle light scattering (SALS) and the shear stress as a function of shear rate, in addition to further analyses of the SANS data.Abstract Effects of shear flow on the structure of a lamellar phase in C 16 E 7 (hepta(oxyethylene glycol)-nhexadecylether)/water system (40-55 wt% of C 16 E 7 ) at 70°C are studied by using small-angle neutron scattering (SANS), small-angle light scattering (SALS), and shear stressshear rate relationships. The repeat distance takes a deep minimum (referred to as d * ) at the shear rate 0.1-1 s )1 . As the concentration of C 16 E 7 decreases, the repeat distance at rest increases whereas d * remains almost constant and nearly equal to the thickness of bilayers obtained from the line shape analysis of small angle X-ray scattering at rest. These results suggest that the water layer is excluded by shear flow and that the lamellar phase segregates into surfactant-rich and water-rich regions. Although macroscopic phase separation does not occur, SALS intensity takes a maximum at the shear rate giving d * , which is consistent with the SANS results. Mechanism for the decrease in the repeat distance is discussed in relation to the change in the size of the lamellar domains.

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“…In many lyotropic lamellar systems under shear flow [1][2][3], lamellae are ordered parallel to the flow-shear gradient plane (perpendicular orientation; Fig. 1) at high shear rates and at low shear rates lamellae show the parallel orientation where the lamellae are ordered parallel to the flow-vorticity plane.…”

Section: Introductionmentioning

confidence: 99%

Shear-induced ordering of lamellar and gyroid structures observed in a nonionic surfactant/water system

Imai

Nakaya

Kato

2001

The European Physical Journal E

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The shear-induced ordering of lamellar and gyroid structures of a nonionic surfactant C16E7/D2O system in a Couette shear cell (0.001 <γ < 10 s −1 ,γ: shear rate) has been investigated by using a small angle neutron scattering technique. In the lamellar phase, the steady shear flow havinġ γ > 0.01 s −1 suppresses undulation fluctuations of lamellae (Maxwell effect). This suppression of fluctuations brings two effects; 1) shear-induced lamellae ordering toward a parallel orientation and 2) obstruction of a lamellar→gyroid transition. It is quite interesting to note that there is a characteristic shear rate range (0.01 <γ < 0.3 s −1 ), where both effects take place. We have also investigated the shear effects on the gyroid phase. Below the characteristic shear rate range, the gyroid structure keeps three-dimensional network lattice, while above the characteristic shear rate range, the gyroid structure transforms to the parallel orientation lamellae (shear-induced gyroid-lamellar transition). Thus the shear flow having the characteristic shear rate plays very important roles in shear ordering phenomena.

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Shear-Induced Transformations in the Lamellar Phase of Hexaethylene Glycol Monohexadecyl Ether

Cited by 72 publications

References 21 publications

Shear-Induced Structures in Concentrated Surfactant Micellar Phases

Shear-Induced Structures in Concentrated Surfactant Micellar Phases

Effects of shear flow on structures of lamellar phase in a nonionic surfactant/water system

Shear-induced ordering of lamellar and gyroid structures observed in a nonionic surfactant/water system

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