Dresden 2011 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 34: Poster: Elastomers and Gels
CPP 34.9: Poster
Wednesday, March 16, 2011, 17:00–19:00, P2
Energy Transfer as a Probe for Studying the Phase Transition of Oligo(ethyleneglycol) based Thermoresponsive Hydrogels — •Sahika Inal1, Jonas David Kölsch2, Dietmar Janietz3, André Laschewsky2, and Dieter Neher1 — 1Uni. of Potsdam, Inst. of Physics and Astronomy, 14476, Golm, Germany — 2Uni. of Potsdam, Applied Polymer Chemistry, 14476, Golm, Germany — 3Fraunhofer Inst. for Applied Polymer Research, 14406, Golm, Germany
Since their discovery, the thermally induced phase transition of thermoresponsive polymers have been widely studied by various techniques. At the temperature known as lower critical solution temperature (LCST), the polymer chains demonstrate a transition from a hydrated state to a collapsed structure, offering an excellent model to investigate molecular interactions at play. In the present study, we use energy transfer (RET) between a conjugated polymer nanoparticle (NP) and a dye labeled thermoresponsive polymer to monitor the coil globule transition of the polymer. The internal structure of this aqueous polymer solution is investigated by fluorescence spectroscopy and dynamic light scattering measurements. When the mixture is heated above LCST, the RET is more efficient, i.e. the ratio of acceptor to donor fluorescence intensity significantly increases. Simultaneously, the average size of the particles in the mixtures containing NPs undergoes a remarkable increase. We propose that the NPs become imbedded into the dehydrated globules of the collapsed chains of the polymer above LCST, forming larger globules and bringing the acceptor chromophores closer to the donor units attached to the polymer.