Small angle neutron scattering investigation of rodlike micelles aligned by shear flow

Shear-Induced Structures in Concentrated Surfactant Micellar Phases

“…Due to the wide variety and subtlety in micellar phases, a larger number of shear-induced transitions have been observed in amphiphilic systems. These include the shear-induced alignment of rod-like micelles and the many associated complications (Penfold, Staples, Lodi & Tucker, 1995;Lin et al, 1996;Penfold, Staples & Cummins, 1991), isotropic to nematic/lamellar transitions (Berret, Roux, Porte & Lindner, 1994;Safinya, Sirota &Plano, 1991) and lamellar to multilamellar vesicle transitions (Penfold, Staples, Lodi & Tucker, 1995;Diat & Roux, 1993). In this paper, we present two different aspects of shear alignment and shear-induced transformations in lamellar phases of surfactants.…”

“…The water cooling in the inner stator means that the cell acts effectively as its own collimator. 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.…”

“…Safinya et al (1993), Safinya, Siorta & Piano (1991) and Safinya, Sirota, Piano & Bruinsma (1990) have observed similar shear-induced ordering effects in the smectic liquid-crystalline phase of 8CB. X-ray Safinya, Sirota & Piano, 1991) and neutron (Penfold, Staples & Cummins, 1991;Hoffman, Hoffman, Ramscher & Kalus, 1991) small-angle scattering, in combination with Couette shear flow, are important techniques for characterizing shear-induced conformations. An important feature for the effective study of aligned lamellar phases is the ability to make measurements with the neutron beam incident both normal to the flow-vorticity plane (through the cell centre) and normal to the shear gradient-vorticity planes (through the cell side), and this has been demonstrated for both X-rays (Piano, Safinya, Sirota & Wenzel, 1993) and neutrons (Penfold, Staples, Lodi & Tucker, 1995).…”

The Structure of Nonionic Micelles in Less Polar Solvents

“…The scattering pattern now has enhanced scattering in the Q direction, and is consistent with extreme glycerol/water). The relative importance of micellar growth and increased attractive interactions in nonionic surfactants polydispersity or the growth of a shear induced phase (8,9,29) of reduced shape anisotropy. as the cloud point is approached has been extensively discussed (see, for example, 24, 25, 27).…”

Novel Synthesis of Aluminium Oxide Nanofibers

“…In liquid phase the alkyl chains of PEO surfactants prefer to stack close to each other, and so do their oxide groups, forming micelles. When the surfactant is dispersed in a polar media, such as in aqueous systems or polar surfaces, the oxide groups would form the outer surface of the micelles, being in contact with the polar media [10][11][12], in this case, the surface of boehmite crystallites. The shift in the diffraction peak to a lower angle is indicative of the interaction between oxide groups of the surfactants and the surface of boehmite crystallites.…”