Institut Charles Sadron Membre

Stéphane Pivard

  • Téléphone : 03.88.41.41.17
  • Courriel : stephane.pivard@ics-cnrs.unistra.fr
  • Doctorant(e)
  • Bureau : B254
  • Equipe : MIM
  • Responsable : Wiebke Drenckhan
  • Sujet : Structure et stabilité des mousses stabilisée par des multi-couches de polyéléctrolytes
  • Sujet : Structure and stability of foams stabilised by polyelectrolyte multilayers

Qualifications:

2018: Master degree "International Master of Polymer Science" (Université de Strasbourg / Albert Ludwigs Universität - Freiburg im Breisgau)

2016 : Bachelor's Degree "Mathematical Physics and Chemistry" with a specialization in material sciences (Université de Strasbourg)

Position:

Since september 2019 : PhD student under supervision of Dr Wiebke DRENCKHAN and Dr François SCHOSSELER

Keywords: Interfacial rheology, LbL deposition at liquid/air interface, Microfluidics


General approach:

The overall goal of my PhD thesis is to use a model system of "bubbloons" with well-controlled polymer skins to establish how the properties of these interfaces modify the interactions between the bubbles - and thus the resulting foam structures. It was defined that Layer-by-Layer (LbL) deposition in an aqueous medium would be a relevant first approach. To do this, successive layers of polyelectrolytes of opposite charges are deposited on the surface of a bubble. This results in the formation of a resistant skin whose thickness and mechanical properties can be controlled (type of polyelectrolytes, number of layers, pH of the medium, salt concentration, etc.). The study of interactions will be carried out in a second step, first with a double bubble system which will allow to characterize the interactions between bubbles.


Next, foam generation will be made possible by coupling LbL layer assembly to microfluidic techniques for careful control of bubble size distribution. Then the foam structure obtained will be analyzed by X-ray tomography. The knowledge of the interactions between bubbles, together with the study of the structural properties of the generated foams, will then allow a better understanding of the relationships between structure/mechanical properties of objects composed of assemblies of deformable units whose interactions are governed solely by their interfacial properties. Finally, in collaboration with the MSC in Paris Diderot, we will explore the impact of these new structures on sound propagation, with the long-term goal of creating acoustic metamaterials that prohibit the transmission of certain acoustic frequency ranges.