Schaltbare Mikrogele an Öl-Wasser Grenzflächen

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Stimuli-sensitive emulsions are prepared employing pH and temperature sensitive microgels. In this project we investigate the interfacial activity of poly (N-isopropylacrylamide (PNiPAM) based microgels and properties of the emulsions stabilized with these microgels in order to understand the mechanism of emulsion stabilization. In particular the relevance of viscoelastic properties of the microgel covered interface as well as the influence of microgel charges are examined. For this purpose several parameters are varied as, e.g., the comonomer composition and architecture of the microgels, the type of oil, the volume fraction and the emulsification procedure on the emulsion stability and several different experimental techniques are employed. The correlation of interfacial tension and interfacial mechanical properties with the thermo- and pH- responses of the emulsions are examined by interfacial rheometry and the colloidal suprastructures of the switchable microgels at the interface are detected by freeze-fraction cryogenic scanning electron microscopy (Cryo-SEM). Micro-fluidic devices are used to visualize the influence of system parameters on the process of droplet coalescence after controlled collision.