Berlin 2015 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 38: Wetting, Micro and Nanofluidics (joint session CPP/ DY)
DY 38.9: Vortrag
Mittwoch, 18. März 2015, 17:15–17:30, C 243
Surfactants in droplet-based microfluidics – Adsorption, Exchange and Biocompatibility — •Birte Riechers1,2, Philipp Gruner2, Florine Maes1,2, and Jean-Christophe Baret1,2 — 1Center de Recherche Paul Pascal, Bordeaux, France — 2Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
Emulsions are omnipresent in industry, research and daily life. They are widely used in painting materials, cosmetics as well as for medical and biotechnology applications [Bremond et al. Soft Matter 2012]. Emulsions are multiphase liquids stabilised using surfactants. These amphiphilic molecules adsorb to interfaces changing their properties (e. g. surface tension, interfacial rheology) [Baret Lab Chip 2012]. They also chemically or physically interact with the dispersed aqueous phase effecting solubility of solutes in all phases [Skhiri et al. Soft Matter2012].
Here, we analyse the properties of surfactants which result in undesirable reactions and interactions with the interior of the droplets. We present a microfluidic method to determine the adsorption kinetics of surfactants. The principle is based on miniaturised pH measurements at the micron-scale. We show that the surfactant exchange between the droplet interface and the continuous phase occurs within seconds and significantly effects the loss of chemicals from droplets. Our method provides new means to analyse surfactant interfaces and their interactions with the aqueous phase of emulsion droplets. We anticipate that our approach can be used to optimise surfactants and formulations for applications in emulsion-based biochemical analysis.