Skip to Main content Skip to Navigation
Theses

Suspensions de microgels thermosensibles à la transition vitreuse : Dynamique hétérogène, corrélation, fluctuation et réponse rotationelles d'aiguilles

Abstract : When a liquid is quenched sufficiently rapidly below its solidification temperature, a disordered and out-of-equilibrium solid called glass may be formed instead of the crystal, after a stark slowing down of the dynamics. This glass transition is wide spread but a sound explanation, lying on solid grounds, of the slowing down of the dynamics remains elusive. Colloidal suspensions exhibit such a transition as the particle volume fraction increases rapidly. In this thesis, an experimental study of the dynamics of colloidal suspensions of thermosensitive microgels is performed as the glass transition approaches and beyond. The diameter of these soft spheres depends on the bath temperature, which enables to reversibly tune the volume fraction of the suspension and thus to study the glass transition continuously on a single sample. First, the dynamic heterogeneities which grow simultaneously to the slowing down of the dynamics, and play a major role in the theories trying to explain the glass transition, are studied using video microscopy particle tracking. On short time scales a purely spatial heterogeneity of the dynamics is found to develop. Slow and rapid domains of homogeneous dynamics coexist in the suspension, the amplitude of the differences in dynamics is found to increase as the glass transition approaches. The spatial extent of the homogeneous domains is then measured using image correlation, which is found to grow when approaching the glass transition. Finally, a method for probing the three dimensional rotational Brownian motion of micrometric wires is developed and applied to measuring the microrheological properties of complex fluids and then to the comparison of fluctuations and dissipation function, measured through the rotational response of the superparamagnetic wires to oscillating magnetic fields, in model fluids and then in glassy suspensions.
Complete list of metadatas

Cited literature [213 references]  Display  Hide  Download

https://tel.archives-ouvertes.fr/tel-00751204
Contributor : Rémy Colin <>
Submitted on : Monday, November 12, 2012 - 9:54:12 PM
Last modification on : Friday, April 10, 2020 - 5:09:11 PM
Long-term archiving on: : Saturday, December 17, 2016 - 9:44:09 AM

Identifiers

  • HAL Id : tel-00751204, version 1

Citation

Rémy Colin. Suspensions de microgels thermosensibles à la transition vitreuse : Dynamique hétérogène, corrélation, fluctuation et réponse rotationelles d'aiguilles. Matière Molle [cond-mat.soft]. Université Paris-Diderot - Paris VII, 2012. Français. ⟨NNT : PARVII 9545898⟩. ⟨tel-00751204⟩

Share

Metrics

Record views

429

Files downloads

745