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Jeudi 24 mars à 10h : Séminaire GIMD de Pavlik Lettinga : « Probing the microstructural origin of complex flow behaviour »

Jeudi 24 mars 2016 à 10h : Séminaire GIMD de Pavlik Lettinga : « Probing the microstructural origin of complex flow behaviour »

- Soft matter materials can classically be characterized by their mechanical response to shear flow, so by rheology. Knowledge of the material structure in flow is, however, crucial to understand, predict and tune flow behaviour and therefore the rheological response. In this talk I will show how time-resolved scattering and microscopy techniques can be employed to probe the structure of materials in situ, during the rheological experiment, and thus to establish a link between the micro structure and the macroscopic response.
- Time-resolved neutron scattering [1, 2] and confocal microscopy[3] were used to study the non-linear response of several supra-molecular polymers. A novel X-ray set-up was used to study the yielding behaviour of nematic dispersion of colloidal platelets, the most common colloidal system in nature[4]. This set-up allows for the 3D reconstruction in situ of the structure and highlights the effect that confinement has on complex flow behaviour.

  • 1. Lonetti, B., et al., Dynamic response of block copolymer wormlike micelles to shear flow. J. Phys. : Condens. Matter, 2008. 20 : p. 404207.
  • 2. Rogers, S.A., J. Kohlbrecher, and M.P. Lettinga, The molecular origin of stress generation in worm-like micelles, using a rheo-SANS LAOS approach. Soft Matter, 2012. 8 : p. 7831.
  • 3. Kirchenbuechler, I., et al., Direct visualization of flow-induced conformational transitions of single actin filaments in entangled solutions. Nature Communications, 2014. 5.
  • 4. Lettinga, M.P., et al., Nonlinear Behavior of Nematic Platelet Dispersions in Shear Flow. Phys. Rev. Lett., 2012. 109 : p. 246001.

Infos pratiques

  • Thème du séminaire : Probing the microstructural origin of complex flow behaviour
  • Conférencier : Pavlik Lettinga, Institute of Complex Systems (ICS-3) Forschungszentrum Jülich, Germany
  • Quand : Jeudi 24 mars 2016 à 10h
  • Où ? : Salle Mathis, bât. 2R1 Campus UPS-Rangueil