In our research group, we have for several years studied interconnected physical phenomena in clays, thus using clays as model systems for soft and complex matter. Within this general context, we have experimentally studied phenomena such as:
(i) spontaneous gravitationally induced phase separation and self-organization in systems of anisotropic nanoparticles in suspension, including isotropic to nematic transitions [1,2,3]
(ii) transitions in magnetic field from biaxial to uniaxial nematics of anisotropic (diamagnetic) nanoparticle systems [4,5]
(iii) guided self-organization into dipolar chain-structures of anisotropic nanoparticles in suspension when subjected to external electrical fields [6,7]
(iv) stability of soft self-organized nanoparticle structures subjected to external mechanical stress [8,9]
(v) role of structured water in the context of (i)-(iv) [10,11]
(vi) diffusion and spontaneous imbibiton of fluids in nanoporous materials [12,13]
The experimental techniques used include (synchrotron) X-ray scattering, neutron scattering, rheometry. microscopy and magnetic resonance. Synchrotron experiments have been performed at LNLS-Brazil, PLS- Korea, BNL-USA, Maxlab Sweden and ESRF-France, rheometry studies at NTNU and also at ENS-Paris/University of Amsterdam, and MR studies at UFPE, Recife, Brasil.
Acknowledgments: Collaborators, postdocs and students at NTNU-Norway, Univerity of Oslo-Norway, Institute for Energy Technology-IFE-Norway, Brookhaven National Lab.-USA, LNLS-Brazil, UFPE-Recife-Brazil, UnB-Brasilia-Brazil, Univ. Amsterdam-Netherlands, Ecole Normal Superieur-Paris-France, Univ.Paris 7-France and other places. The various studies have been supported by the Research Council of Norway (RCN), through the NANOMAT, SUP, FRINAT and CLIMIT Programs.
References:
[1] J.O. Fossum, E. Gudding, D.d.M. Fonseca, Y. Meheust, E. DiMasi, T. Gog, C. Venkataraman, Observations of orientational ordering in aqueous suspensions of a nano-layered silicate, ENERGY The Int. Journal 30, 873 (2005)
[2] D. d.M.Fonseca, Y. Meheust, J.O. Fossum, K.D. Knudsen and K.P.S. Parmar, Phase diagram of polydisperse Na fluorohectorite–water suspensions: A synchrotron small angle x-ray scattering study, Phys.Rev. E 79, 021402 (2009)
[3] N.I. Ringdal, D.M. Fonseca, E.L. Hansen, H. Hemmen, and J.O. Fossum, Nematic textures in colloidal dispersions of Na-fluorohectorite synthetic clay, Phys.Rev. E 81, 041702 (2010)
[4] E. N. de Azevedo, M. Engelsberg, J. O. Fossum, R. E. de Souza, Anisotropic water diffusion in nematic self-assemblies of clay nano-platelets suspended in water, Langmuir 23, 5100 (2007)
[5] H. Hemmen, N.I. Ringdal, E.N. De Azevedo, M. Engelsberg, E.L. Hansen, Y. Meheust, J.O. Fossum, K.D. Knudsen, The Isotropic-Nematic Interface in Suspensions of Na-Fluorohectorite Clay, Langmuir 25, 12507 (2009)
[6] J.O. Fossum, Y. Meheust, K.P.S. Parmar, K.D. Knudsen, K.J. Maloy, D.d.M. Fonseca, Intercalation-enhanced electric polarization and chain formation of nano-layered particles, Europhys. Lett., 74, 438 (2006), and in Scientific Highlights 2006 of the European Synchrotron Radiation Facility – ESRF (2007)
[7] Z Rozynek, K.D. Knudsen, J.O. Fossum, Y. Meheust, B Wang and M Zhou, Electric field induced structuring in clay–oil suspensions: New insights from WAXS, SEM, leak current, dielectric permittivity, and rheometry, J. Phys.: Condens. Matter 22, 324104 (2010)
[8] K.P.S. Parmar, Y. Meheust, B. Schelderupsen and J.O. Fossum, Electrorheological suspensions of laponite in oil: rheometry studies, Langmuir 24, 1814 (2008)
[9] A. Khaldoun, P.Moller, A. Fall, G.Wegdam,B. De Leeuw, Y. Meheust, J.O. Fossum, D. Bonn, Quickclay and Landslides of Clayey Soils, Phys.Rev.Lett. 103, 188301 (2009)
[10] R. Tenorio, L. Alme, M. Engelsberg, J.O. Fossum and F. Hallwass, Geometry and Dynamics of Intercalated Water in Na-Fluorhectorite Clay Hydrates, J.Phys.Chem.C, 112,575-580 (2008)
[11] R. P. Tenorio, M. Engelsberg, J.O. Fossum and G. J. da Silva, Intercalated Water in Synthetic Fluorhectorite Clay, Langmuir 26, 9703 (2010)
[12] E. N. de Azevedo, L.R. Alme, M. Engelsberg, J.O. Fossum and P. Dommersnes, Fluid imbibition in paper fibers: Precursor front, Phys.Rev.E 78, 066317 (2008)
[13] H. Hemmen, L.R. Alme, J.O. Fossum and Y. Meheust, X-ray studies of interlayer water absorption and mesoporous water transport in a weakly hydrated clay, Phys.Rev. E 82, 036315 (2010), Erratum: Phys.Rev. E 83, 019901(E) (2011)
Department of Physics, Norwegian University of Science and Technology-NTNU, Trondheim, Norway