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Polyelectrolyte complexes & coacervates : Kinetic, thermodynamic and morphological aspects - Jean-Paul CHAPEL

Centre de Recherche Paul Pascal, Pessac


LPS Moyen Amphi

The complexation of oppositely charged polyelectrolytes (PEs) through electrostatic interaction is a ubiquitous associative process found in both natural and synthetic systems and involves at charge stoichiometry two distinct stages : the generation of primary PECs via ion-pairing interactions followed by their aggregation/reorganization into larger structures through either a liquid-solid or a liquid-liquid phase transition. Depending on the strength of the attractive interaction, the resulted macrophase separated mixture will indeed display either a solid-like precipitate or a liquid-like coacervate. In both cases, a dense polymer-rich phase separates from the dilute polymer-poor solution phase (aqueous phase). Far from the charge neutrality the distinction between the two types of systems can be more difficult to establish as different morphologies can be found spanning from the controversial soluble complexes to the insoluble or dispersed ones. With the help of two synthetic PE pairs (PSS/PDADMAC and PANa/PDADMAC), we will put forward some distinctive structural (light, neutron and X-Ray scattering, AFM…) kinetic (Stopped-Flow, dialysis…) and thermodynamic (calorimetry…) features in order to better understand when, why and how the different PECs appear. An important issue since such coacervate complexes present several applications in cosmetic, food, pharmaceutic, and biomedicine industry through their encapsulating capabilities and great premises in synthetic biology as scaffold for artificial cell.

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