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Sujet de stage / Master 2 Internship

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Wetting dynamics of polymer liquids from the macro to the nanoscale

Contact: GRZELKA Marion, , marion.grzelka@cea.fr, +33 1 69 08 60 57
Summary:
The aim of this project is to understand the mechanisms of energy dissipation during spontaneous spreading of a drop on a nanotextured substrate. As part of this internship, the student will study the wetting of nanotextured surfaces by conventional optical microscopy techniques (to probe macroscopic scales) and X-ray reflectivity (to probe nanoscopic scales).
Possibility of continuation in PhD: Oui
Deadline for application:17/04/2024

Full description:
Situations where a liquid covers a surface, known as dynamic wetting, is nowadays well understood when liquids spread on flat solid substrates. Nevertheless, real life substrates are not atomically flat. Then, a difficulty to describe this phenomenon comes from the broad range of length scales involved, from the millimeter size of a drop to the nanometric range of
the liquid/substrate interaction.
Indeed, energy dissipation mechanisms at the contact line are still largely unknown on rough surfaces. On atomically flat, chemically homogeneous surfaces, it has been shown that a film, known as the precursor film, precedes the macroscopic drop. The presence of this film was predicted theoretically, but was difficult to observe experimentally due to its small thickness (<100 nm). How nanometric roughness, with a characteristic size close to the precursor film thickness, influences the spreading behaviors is still an open question.

The aim of this project is to understand how purely topographic roughness at the nanoscale affect the spontaneous spreading dynamics of a liquid. Notably, can a precursor film form and propagate ? What are the energy dissipation mechanisms involved in wetting nanotextured surfaces?

In this internship, the student will prepare and characterize ( atomic force microscopy and X ray reflectivity) the nanotextured surfaces. They will then study the wetting of these surfaces with silicone oils. Conventional optical microscopy techniques will be used to probe macroscopic scales. Nanometric scales will be probed by X ray reflectivity (device available at LLB).
Technics/methods used during the internship:
- AFM - classical microscopy techniques - X ray reflectivity

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