I am an experimental physical chemist working in soft matter and colloid science with a focus on foams and emulsions. I entered this field during my Masterâ€™s thesis via the problematic of the stability of these systems (surfactant-stabilised emulsions, Pickering emulsions, antifoams, â€¦). My PhD Thesis allowed me to bridge the fields of soft matter and material science by working on the solidification of initially liquid foams using the so-called foam templating method.
Foam templating consists in generating a liquid foam with a controlled morphology in which the liquid phase is a complex fluid that can be solidified. The structure of the solidified foam is set by that of the liquid foam template and the solidification procedure. As sketched in Figure 1, my research interests revolve around developing a sound understanding of a wide range of phenomena and processes at play for the obtention the â€śperfectâ€ť solid foam from a complex fluid.
Figure 1: General scheme of a common foam templating route going from the foaming solution to the solid foam with the desired structure and properties. My research aims at identifying which properties/parameters of each step may be used as levers to obtain the â€śperfect foamâ€ť for a given application. The fundamental aspect of this research relies on the understanding of structure/properties relations.
The different steps of foam templating are:
(i) The formulation of the foaming solution that should be solidified once foamed. Two major properties are investigated at this scale: the rheological propertiesâ€”which play a strong part in the foaming process and foam stabilityâ€”and the interfacial propertiesâ€”which play a strong part in foam stability and pore opening. As of now, I have mainly worked on polysaccharide solutions which can be chemically or physically cross-linked and polyurethanes. I aim at expanding my research to new classes of complex fluids, such as emulsions, proteins, latexesâ€¦
(ii) The foaming process which consists in dispersing or injecting a chosen gas to form the liquid foam template. The morphology of the obtained liquid foam template strongly depends on the interplay between the foaming procedure and the rheological/interfacial properties of the foaming solution. A feedback loop between the foaming process and the formulation of the foaming solution is thus necessary to obtain the liquid foam template with the desired properties. That is how I developed an expertise in microfluidics to obtain foams with a narrow bubble size distribution (monodisperse foams) and a high level of order. My current research (unpublished results) aims at expanding the use of common foaming methods reserved for low viscosity solutions to more viscous complex fluids.
(iii) The characterisation of the liquid foam, i.e. its stability over time and morphology. Since the aim of foam templating is to obtain a solid foam that is the â€ścopyâ€ť of its liquid counterpart, it is primordial to manage to fine-tune the morphology of the liquid foam template. However, as foams are thermodynamically unstable systems, they tend to destabilise. I thus study the classical foam destabilisation mechanisms (coalescence, coarsening, drainage) for each system to be able to counteract them. A feedback loop to the formulation of the foaming solution is thus necessary to generate and formulate a foam which is stable within the timescale of solidification.
(iv) The solidification procedure must ensure a retention of the liquid foam morphology in a shorter time than the time the foam requires to destabilise. I study first the solidification process in bulk (e.g. oscillatory time sweep of cross-linking or polymerisation), but the confinement of the material between bubbles usually affect the kinetics of solidification and the morphology of the material compared to the bulk. My current research aims at understanding the effects of confinement on cross-linking to shed light on the relationships between confinement, cross-linking, and pore opening.
(v) The final solid foam is characterised via microscopy (morphology, connectivity) and mechanical tests (foam mechanics). Depending on the applications, I also determine the absorption or adhesive properties of the foam. The main task once the foam is obtained is to determine whether the solid foam displays the properties expected from those of the liquid foam template. Any deviation is then investigated by model experiments and feedbacks to each of the earlier steps, until the â€śperfect foamâ€ť can be produced in a reproducible manner.
My research activities, although seemingly only revolving around foams, comprise the physics and physical chemistry of complex fluids, fluid mechanics, the structure and stability of liquid foams, the study of hydrogels, and foam mechanics, amongst others. Each of these domains is or has been the subject of extensive research on its own. However, the necessity to link the properties of the complex fluid to those of a solid foam lays constraints few people had met before. I am passionate about making the bridge between all these problematics (and communities) through the spectrum of my own general problematic.
Since 04/18 - Research Engineer (Institute Charles Sadron, CNRS, FRANCE)
10/14-03/18 - PhD Thesis, Institut fĂĽr Physikalische Chemie, UniversitĂ¤t Stuttgart, Stuttgart, Germany: â€śMonodisperse Highly Ordered and Polydisperse Biobased Solid Foamsâ€ť
02/14-08/14 - MSc Thesis, University of Hull, Surfactant abd Colloid Group, Kingston-upon-Hull, UK
2014-2018 - PhD Thesis, Institut fĂĽr Physikalische Chemie, UniversitĂ¤t Stuttgart, Stuttgart, Germany: â€śMonodisperse Highly Ordered and Polydisperse Biobased Solid Foamsâ€ť
2011-2014 - European School of Chemistry, Polymers and Materials Sciences (ECPM), UniversitĂ© de Strasbourg, France. Diplomas obtained: DiplĂ´me dâ€™IngĂ©nieur (ECPM) and Master in Polymer Engineering (UniversitĂ© de Strasbourg, Faculty of Physics).
2009-2011 - Undergraduate studies for admission to a French chemistry engineering school at the "Ă‰cole Nationale SupĂ©rieure de Chimie de Rennes" (ENSCR), Rennes, France
Drenckhan W. and Stubenrauch C. Highly ordered biobased scaffolds: From liquid
to solid foams, Polymer 2017 87(2): 425â€“431.
Andrieux S., Drenckhan W. and Stubenrauch C. Generation of Solid Foams with Controlled Polydispersity Using Microfluidics, Langmuir 2018 34(4): 1581â€“1590.
Andrieux S., Quell
A., Stubenrauch C. and Drenckhan W. Liquid foam templating â€“ A route to
tailor-made polymer foams, Adv. Colloid Interface Sci. 2018 256:
Andrieux S., Medina L., Herbst M., Berglund L. and Stubenrauch C. Monodisperse Highly Ordered Chitosan/Cellulose Nanocomposite Foams, Composites Part A 2019 125: 105516. (FI : 6,282)