SKM 2021 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 3: Polymer Physics

CPP 3.1: Hauptvortrag

Montag, 27. September 2021, 13:30–14:00, H3

Emulsion Templating: Unexpected Morphology of Monodisperse Macroporous Polystyrene — •Cosima Stubenrauch1, Lukas Koch1, Sophia Botsch1, and Wiebke Drenckhan21Institut für Physikalische Chemie, Universität Stuttgart, Deutschland — 2Institute Charles Sadron, CNRS Strasbourg, Frankreich

We start with a monodisperse, hexagonally close-packed water-in-monomer high internal phase emulsion (HIPE). The polymerization of the continuous monomer phase with a water-soluble initiator leads to a monodisperse, macroporous polymer with an unexpected morphology: the pore cross-sections of this material are closed hexagons and the pore walls consist of three distinctive layers. Though this morphology has already been observed for two different systems, the mechanism leading to it has not been identified yet. Based on new experimental results we propose a surfactant-driven mechanism: excess surfactant is dissolved in the continuous phase, where it emulsifies water from the emulsion droplets. When the polymerization is initiated from the interface, the continuous phase becomes a poor solvent for both the surfactant and the emulsified water. As a consequence, they "flee" from the site of the polymerization (1) towards the water/monomer interface or (2) into the yet unpolymerized inside of the continuous phase. The first process may cause the emulsion droplets to change their shape from spherical to polyhedral and the second process may be responsible for the formation of the three observed layers in the pore wall. We will (a) discuss both processes in detail and (b) present the experimental results that clearly support them.

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