Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 27: Poster: (Hydrogels) and Elastomers

CPP 27.15: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Visualization of the Coil-Globule Transition of a Thermoresponsive Polymer in Mixtures with a Conjugated Polyelectrolyte — •Sahika Inal¹, Jonas D. Kölsch², Dietmar Janietz³, André Laschewsky², Ullrich Scherf⁴, and Dieter Neher¹ — ¹Inst. of Physics and Astronomy, Uni. of Potsdam, Germany — ²Department of Chemistry, Uni. of Potsdam, Germany — ³Fraunhofer Inst. for Applied Polymer Research, Germany — ⁴Macromolecular Chemistry Group, Bergische Uni. Wuppertal, Germany

Changes in the physical environment of smart polymers alter the intermolecular interactions that stabilize their chains in water, which translates into macroscopic responses such as coil to globule transition. Here, we present a scheme to optically visualize the temperature-induced coil to globule transition of a smart polymer using Förster resonance energy transfer (FRET). The aqueous mixtures of a cationic conjugated polymer electrolyte and a dye-labeled nonionic thermoresponsive polymer at room temperature exhibit reduced fluorescence intensity from the responsive polymer, accompanied by an enhanced emission from the polyelectrolyte, indicative of FRET mechanism. Heating this mixture above the cloud point of the smart polymer strongly reduces the efficiency of FRET. We propose that the two macromolecules form mixed aggregates at room temperature, and that these aggregates are disrupted upon the coil-globule transition. As a consequence, temperature-induced structural changes in these macromolecular complexes are detected as well visible variations of fluorescence signal. This visualization scheme shall be well applicable to biochemical sensors.