Flows in ultra-thin polymer films

Internship proposal

Laboratoire Sciences et Ingénierie de la Matière Molle, (SIMM)

Address: ESPCI, 10 Rue Vauquelin 75005 Paris

Head: Jean-Baptiste d’Espinose

Supervisors: Emilie VERNEUIL, Jean COMTET

Contact :

The stability and homogeneity of liquid films is crucial to processes producing coatings. In the case of silicone oils, a rough estimate of the long-range interactions such as Van der Waals’ shows that such films should bear a uniform thickness at equilibrium: repulsive interactions should tend to a flat thick film. However, in practical situation, initially heterogeneous films never get uniform in a timely manner. As examples, defects on glass substrates lead to thickness heterogeneities that grow over time rather than heal. When starting from a collection of droplets sprayed onto a flat substrate, a nanometer-thick film first spreads around the droplets, and delays the spreading and coalescence of droplets. The goal is to gain insights into the behavior of polymer melts on glass and to elucidate the mechanisms underlying the time evolution of droplets spreading. To do so, model systems will be used (plane glass or silicon wafers, well-characterized polymers), and experiments will be performed in order to measure the thickness profiles over time with advanced imaging techniques. Modelling of the transfers will then be developped to account for the data. Two cases will be particularly studied - Time evolution of oil spread onto substrates decorated will well-controlled defects - Spreading dynamics of several droplets deposited on smooth substrates.

We are looking for a Master 2 student in materials science, physical-chemistry or physics with an interest in soft matter physics. A PhD position funded by a CIFRE may be available following the internship, for candidates demonstrating strong motivation and research potential.

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