Dynamique de capsules en écoulement (thèse 2015 - 2018)
Activités
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Publications scientifiques au M2P2
2023
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩ Plus de détails...
The controlled rupture of a core-shell capsule and the timely release of encapsulated materials are essential steps of the efficient design of such carriers. The mechanical and physico-chemical properties of their shells (or membranes) mainly govern the evolution of such systems under stress and notably the link between the dynamics of rupture and the mechanical properties. This issue is addressed considering weakly cohesive shells made by the interfacial complexation of Chitosan and PFacid in a planar extensional flow. Three regimes are observed, thanks to the two observational planes. Whatever the time of reaction in membrane assembly, there is no rupture in deformation as long as the hydrodynamic stress is below a critical value. At low times of complexation (weak shear elastic modulus), the rupture is reminiscent of the breakup of droplets: a dumbell or a waist. Fluorescent labelling of the membrane shows that this process is governed by continuous thinning of the membrane up to the destabilization. It is likely that the membrane shows a transition from a solid to liquid state. At longer times of complexation, the rupture has a feature of solid-like breakup (breakage) with a discontinuity of the membrane. The maximal internal constraint determined numerically marks the initial location of breakup as shown. The pattern becomes more complex as the elongation rate increases with several points of rupture. A phase diagram in the space parameters of the shear elastic modulus and the hydrodynamic stress is established.
Revaz Chachanidze, Kaili Xie, Jinming Lyu, Marc Jaeger, Marc Leonetti. Breakups of Chitosan microcapsules in extensional flow. Journal of Colloid and Interface Science, 2023, 629, pp.445-454. ⟨10.1016/j.jcis.2022.08.169⟩. ⟨hal-03787637⟩
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, 2021, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03467425⟩ Plus de détails...
The stability of copolymer tethers is investigated theoretically. Self-assembly of diblock or triblock copolymers can lead to tubular polymersomes which are known experimentally to undergo shape instability under thermal, chemical and tension stresses. It leads to a periodic modulation of the radius which evolves to assembly-line pearls connected by tiny tethers. We study the contributions of shear surface viscosity and spontaneous curvature and their interplay to understand the pearling instability. The performed linear analysis of stability of this cylinder-to-pearls transition shows that such systems are unstable if the membrane tension is larger than a finite critical value contrary to the Rayleigh-Plateau instability, an already known result or if the spontaneous curvature is in a specific range which depends on membrane tension. For the case of spontaneous curvature-induced shape instability, two dynamical modes are identified. The first one is analog to the tension- induced instability with a marginal mode. Its wavenumber associated with the most un- stable mode decreases continuously to zero as membrane viscosity increases. The second one has a finite range of unstable wavenumbers. The wavenumber of the most unstable mode tends redto be constant as membrane viscosity increases. In this mode, its growth rate becomes independent of the bulk viscosity in the limit of high membrane viscosity and behaves as a pure viscous surface.
J Lyu, K Xie, R Chachanidze, A Kahli, Gwenn Boedec, et al.. Dynamics of pearling instability in polymersomes: the role of shear membrane viscosity and spontaneous curvature. Physics of Fluids, 2021, 33 (12), pp.122016. ⟨10.1063/5.0075266⟩. ⟨hal-03467425⟩
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩ Plus de détails...
Tuning the mechanical properties of microcapsules with cost-efficient route of fabrication is still a challenge. The traditional method of layer-by-layer assembly of microcapsules allows building a tailored composite multi-layer membrane but is technically complex as it requires numerous steps. The objective of this article is to characterize the interfacial rheological properties of self-assembling biopolymer microcapsules that were obtained in one single facile step. This thorough study provides new insights in the mechanics of these weakly cohesive membranes. Firstly, sus-pensions of water-in-oil microcapsules were formed in microfluidic junctions by self-assembling of two oppositely charged polyelectrolytes, namely chitosan (water soluble) and phosphatidic fatty acid (oil soluble). In this way, composite membranes of tunable thickness (between 40-900 nm measured by AFM) were formed at water / oil interfaces in a single step by changing the composition. Secondly, microcapsules were mechanically characterized by stretching them up to break-up in an extensional flow chamber which extends the relevance and convenience of the hydrodynamic method to weakly cohesive membranes. Finally, we show that the design of micro-capsules can be 'engineered' in a large way since they present a wealth of interfacial rheological properties in term of elasticity, plasticity and yield stress whose magnitudes can be controlled by the composition. These behaviors are explained by the variation of the membrane thickness with the physico-chemical parameters of the process.
Kaili Xie, Clement de Loubens, Frédéric Dubreuil, Deniz Gunes, Marc Jaeger, et al.. Interfacial rheological properties of self-assembling biopolymer microcapsules. Soft Matter, 2017, 13 (36), pp.6208-6217. ⟨10.1039/C7SM01377A⟩. ⟨hal-02020103⟩
