Dresden 2006 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 27: POSTER Polymer Physics and Materials

CPP 27.21: Poster

Donnerstag, 30. März 2006, 17:00–19:00, P2

Investigation of spatially confined polyelectrolytes using fluorescence microscopy — •Daniel Rapoport¹, Dan Anghel², Helmuth Möhwald¹, and Regine v. Klitzing³ — ¹MPI für Kolloid- und Grenzflächenforschung, D-14224 Potsdam — ²Institute of Physical Chemistry, Spl. Independentei 202, RO-77208 Bucharest — ³Institut für Physikalische Chemie, CAU Kiel, Ludewig-Meyn-Strasse 8, D-24118 Kiel

Confinement phenomena are common to a vast number of natural and technical processes, such as the transfer of proteins or DNA through a narrow pore, filtration or nanoencapsulation. The effect can be intermolecular like an increased ordering of the molecules or it can be intramolecular like conformational changes. In the case of aqueous solutions of polyelectrolytes it is largely unknown, how these respond to the restrictions of geometrical confinement. Although numerous investigations of integral thermodynamic values have been carried out, a detailled molecular picture is still missing. Here we report on fluorescence measurements with pyrene labeled poly(acrylic acid) inside thin free standing liquid films, which were formed using sodium dodecylsulfate (SDS) as a surfactant. Upon film formation we found an increase of the excimer/monomer fluorescence intensity ratio. Moreover, at high pH stratification of the film leads to an additional rise of the excimer/monomer ratio, thereby directly proving the confinement effect on a molecular level.