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Reference : UMR5221-LAURAM-001
Workplace : MONTPELLIER
Date of publication : Wednesday, February 05, 2020
Scientific Responsible name : Laurence Ramos
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 September 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly
Description of the thesis topic
Understanding the response of gels under stress is of paramount importance, both fundamentally and in applications. In this general framework, we will produce unique spherical beads of gel of millimetric size. The gels are based on colloidal particles and consist in a homogeneous porous stress-bearing network structure, and we will vary in a controlled manner their mechanical properties. Our objective is to rationalize the fate of these beads under stress and to elucidate the complex interplay between the flow of liquid through the pores (the poroelasticity), the plasticity of the network-forming structure and the fracture of the network.
We will use a multiscale approach that combines mechanical creep under indentation, image analysis, and time- and space-resolved light scattering. Our project is fundamental, but we will mainly investigate two configurations of uttermost relevance in applications: the drying/swelling of the beads and their response to an extreme mechanical deformation produced by impact on a solid surface.
We will explore several strategies to produce unique beads of colloidal gels with tunable toughness and brittleness. Drying, swelling, and eventually several cycles of drying and swelling, will be investigated in a multiscale approach, gathering macroscopic structural information on the instabilities developed by the bead and microscopic dynamic information on the rearrangements of the colloid forming the stress-bearing network structure. Finally, we will investigate how the beads of gel behave upon impact on a repellent surface. Macroscopic information on the fragmentation process undergone by the beads will be acquired here, but on a drastically different regime as the one explored in the drying/swelling protocol, as poroelasticity does not play any role due to the very short time scale of the experiment.
This project is part of the ANR-BOGUS project, in collaboration with the team of ludovic Pauchard, at the FAST laboratory in Orsay.
The work will be carried out within the Soft Matter team (https://www.coulomb.univ-montp2.fr/- Equipe-Matiere-Molle-) of the Charles Coulomb Laboratory in Montpellier, France, under the direction of Laurence Ramos, in close collaboration with Christian Ligoure and Luca Cipelletti.
The successful candidate will have a solid a solid background in condensed matter physics, soft matter or material science
Expected level of study: Master or engineering school. Language: English and / or French
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