Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 29: POSTER: Polymer physics

CPP 29.65: Poster

Dienstag, 8. März 2005, 16:30–18:30, Poster TU D

Effect of spatial confinement on polyelectrolyte conformation — •Daniel H. Rapoport, Dan F. Anghel, Helmuth Möhwald, and Regine v. Klitzing — Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Golm, Germany

Intermolecular forces between polyelectrolytes in aqueous solutions govern a great number of important phenomena: From the folding and targeting of proteins in cells to the rheology of modern water based paints. One particular question of interest is the behaviour of polyelectrolytes, when put inside a geometrically confined environment, such as a pore or a slit.

Free standing foam films, which are essentially an ultrathin slab (5-100 nm) of surfactant solution provide a unique tool for pursuing this question. When adding polyelectrolytes to the solution, raising the gas pressure in a sealed chamber excerts very defined forces onto the molecules in solution. This way, force oscillations have been measured, which were attributed to structural forces between the polyelectrolytes.

One advantage of free standing foam films over other ways of confining the solutes, is the easy allowance for a combination with optical methods, such as fluorescence spectroscopy. In order to gain insight on a mlolecular level, rather than an integral behaviour, we have labeled poly(acrylic acid) with pyrene fluorescent probes. Upon film formation an increase of the excimer emission intensity can be observed at the expense of monomer fluorescence.