Dresden 2014 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Colloids and Complex Liquids II

CPP 36.3: Talk

Wednesday, April 2, 2014, 15:30–15:45, ZEU 114

Fluorescence Correlation Spectroscopy Directly Monitors the Equilibrium Chain Exchange Kinetics of Diblock Copolymer Micelles — •David Schaeffel, Andreas Kreyes, Yi Zhaou, Daniel Crespy, Katharina Landfester, Hans-Jürgen Butt, and Kaloian Koynov — Max Planck Institute for Polymer Research, Mainz, Germany

We present a new method for monitoring the equilibrium exchange kinetics of building molecules between amphiphilic diblock copolymer micelles. The method is based on dual color fluorescence cross correlation spectroscopy (DC FCCS) and offers single molecule sensitivity. We demonstrate its versatility by studying polystyrene-block-poly[oligo(ethylene glycol) methyl ether methacrylate] (PS-b-POEGMA) micelles in different selective solvents and solvent-mixtures at various temperatures. If pure water is used as a selective solvent, no exchange could be observed at temperatures below the glass transition of the core forming PS block. In methanol, the exchange persists even at temperatures well below the PS glass transition suggesting that the methanol swells the micelles core. However, adding only small amounts of bad or good solvents can slow down or fasten the kinetics by orders of magnitude. Our findings demonstrate that DC FCCS is a fast and reliable tool to study the dynamic equilibrium exchange kinetics of copolymer micelles.