In situ magnetorheological SANS setup at Institut Laue-Langevin
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INVITED ARTICLE
In situ magnetorheological SANS setup at Institut Laue-Langevin Dominika Zákutná 1,2,3 Sabrina Disch 1
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Kevin Graef 1 & Dominique Dresen 1
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Lionel Porcar 2 & Dirk Honecker 2,4
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Received: 9 April 2020 / Revised: 30 June 2020 / Accepted: 21 July 2020 # The Author(s) 2020
Abstract A magnetorheological sample environment is presented that allows for in situ magnetic field and shear flow during small-angle neutron scattering (SANS) measurements and is now available at the Institut Laue-Langevin (ILL). The setup allows performing simultaneous magnetorheological measurements together with the investigation of structural and magnetic changes on the nanometer length scale underlying the rheological response of ferrofluids. We describe the setup consisting of a commercial rheometer and a custom-made set of Helmholtz coils and show exemplarily data on the field and shear flow alignment of a dispersion of hematite nanospindles in water. Keywords Small-angle neutron scattering . Magnetorheology . Rheology . Magnetoviscous effect . Magnetic nanoparticles
Introduction Recent progress toward magnetic soft matter combines the unique properties of soft matter and magnetic materials into complex magnetic fluids, such as original or inverse ferrofluids, ferrogels, and ferroelastomers [1–9]. Complex magnetic fluids find technological application in vibro-protection, lubrication, and for the precise control of polishing processes [10, 11], actuators and sensors such as shapeprogrammable matter [12], as well as the field-controlled release of incorporated drugs [13–15]. Ferromagnetic liquid crystals combine nematic order as well as ferromagnetic order and show non-Newtonian behavior in flow field [16–19]. Magnetic nanorod dispersions have been further demonstrated as in situ and non-contact viscosity gauges,
* Sabrina Disch [email protected] 1
Department für Chemie, Universität zu Köln, Greinstraße 4-6, 50939 Köln, Germany
2
Institut Laue-Langevin, 71 Avenue des Martyrs, F-38042 Grenoble, France
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Present address: Department of Inorganic Chemistry, Faculty of Science, Charles University in Prague, Hlavova 2030/8, 12843 Prague 2, Czech Republic
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Present address: Physics and Materials Science Research Unit, University of Luxembourg, 162A Avenue de la Faïencerie, L-1511 Luxembourg, Grand Duchy of Luxembourg
being suitable probes for active microrheology [20]. The rotational friction of magnetic nanorods is sensitive to the stiffness of hydrogels [21] or the viscosity of liquid samples [22]. Recording the concomitant orientational redistribution with AC susceptibility, optical transmission spectroscopy [23], depolarized dynamic light scattering [24], SAXS [25], or SANS [26] enables to extract hydrodynamic properties of the carrier medium. Magnetic fluids consist of magnetic particles suspended in a non-magnetic carrier liquid. With the assistance of a magnetic field, the dynamics and hence the flow properties of the dispersion can be tuned. The fluid-mechanical properties are determined by the p
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