RheoSAXS studies of anisotropic complex fluids under shear

Abstract

Cylindrical intermediates in a shearinduced lamellar-to-vesicle transition J. Zipfel, F. Nettesheim, P. Lindner et al.Rheo-SAXS investigation of shear-thinning behaviour of very anisometric repulsive disc-likeclay suspensions A M Philippe, C Baravian, M Imperor-Clerc et al. Abstract. We discuss the application of in-situ rheological small angle X-ray scattering experiments to the study of complex fluids under shear, implemented using custom Couette cylinder rheometers mounted on the SWING beamline of the SOLEIL Synchrotron. We discuss several applications of this technique to the study of phase transitions in nanoparticle doped liquid crystals and shear alignment of clay suspensions. The concurrent capture of rheological and scattering data provides vital information that relates macroscopic properties such as viscosity to the microstructure of the fluid. IntroductionThe study of complex fluids and of their rheological properties is an active area of research with a wide range of applications.1 The bulk macroscopic properties of complex fluids, such as rheological properties such as shear viscosity, for example, will often depend on the structure of the fluid on a microscopic level. Thus it is often convenient to combine various techniques in order to study macroscopic and microscopic properties at the same time. Investigations using small angle scattering techniques (SAS) (light, neutrons, X-rays) can be performed on such fluids directly under flow; this allows the simultaneous recording of rheological quantities (such as flow-curves and viscosity profiles) and structural information. In the case of strongly anisotropic fluids, small angle X-ray or neutron scattering (SAXS/SANS) experiments are particularly well suited to following orientation phenomena of structured fluids under flow. Using new rheological small-angle (Rheo-SAXS) instruments developed at the SWING SAXS beamline of the SOLEIL synchrotron, we present some examples of results demonstrating in detail the behaviour under shear of doped surfactant lamellar phases and colloidal clay suspensions.

Reversible shear-induced crystallization above equilibrium freezing temperature in a lyotropic surfactant system

“…Rheo-SAXS measurements were performed at the SWING beamline of the SOLEIL synchrotron (Proposal 20110293) using a fixed energy of 15 keV and a sampleto-detector distance of 898.42 mm. An MCR-501 rheometer (Anton Paar) equipped with a Couette cell (with a rotating inner cylinder and a temperature-controlled static outer cylinder, gap = 0.2 mm) was mounted on the SAXS beamline (42). The 2D scattering patterns with the X-ray beam parallel or perpendicular to the flow direction (tangential or radial geometry) were recorded on an AVIEX CCD camera formed by four detectors, and appropriate corrections were applied to the data (SI Appendix, Fig.…”

Applications of shear-induced polarized light imaging (SIPLI) technique for mechano-optical rheology of polymers and soft matter materials

“…There is a continuously growing interest in a combination of rotational rheology with other characterization techniques to perform simultaneous measurements of viscoelasticity and extra physical parameters associated with phase transitions, morphological transformations and structural orientation in soft matter materials. In recent decades, the versatility of rheology has been demonstrated by the progress of techniques such as rheo‐infrared, rheo‐Raman, rheo‐optical microscopy, rheo‐SALS (small‐angle light scattering), rheo‐SAXS (small‐angle X‐ray scattering), and rheo‐SANS (small‐angle neutron scattering) . The coupling of these techniques provides invaluable information about the relationship between macroscopic rheological properties and microscopic structural characteristics of materials.…”

External fields for the fabrication of highly mineralized hierarchical architectures

“…The full width at half maximum of the angle distribution is directly available with the rocking curves 44 or by plotting the intensity as a function of the azimuthal angle from SAXS diffraction patterns. 115 In addition, an order parameter S can be extracted from the angle distribution using the following equations:…”

“…Finally, in situ set-ups using electric field 118 or shear-induced manipulation of particles during the measurements can be performed using synchrotron X-rays to give a direct correlation between the forces and torques applied and the alignment obtained. 115,116 Figure 11(b) is a visual summary of the capacity of the fabrication methods to reach high design flexibility with high alignment quality. The first observation is that all after the same crack length.…”