Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 16: POSTERS Polyelectrolytes and Biological Systems

CPP 16.17: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Formation of necklace structures for intermediates of a Ca2+ induced shrinking of dilute anionic polyacrylate chains — •Prashant Sinha1, Sebastian Lages2, Anton Kiriy1, Manfred Stamm1, and Klaus Huber21Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Strasse 6, 01069 Dresden, Germany — 2Chemsitry Department, Universität Paderborn, Warburger Str.100, D-33098 Paderborn, Germany

Sodium polyacrylate coils in dilute aqueous solutions shrink drastically upon addition of stoichiometric amounts of Ca2+ ions. An essential feature of this shrinking mechanism is its enhancement upon increase of temperature. The conformational changes in response to the addition of Ca2+ cations and upon an increase of temperature are investigated by means of light and neutron scattering and by AFM on the same samples. To this end, partially collapsed coils at 15°C were further shrunken and modified in shape by increasing the temperature to 30°C. The scattering curves at 30°C could only be interpreted with a model, which included the feature of a dumbbell, a reflection of necklace-like shape. Supplementary AFM imaging supports the drastic changes inferred to the system upon addition of the Ca2+ cations and upon a temperature increase by 15°C. AFM images have been analysed for radius of gyration of single molecules and evaluation of a 2D form factor curve. The information obtained is compared with scattering data. The results are considered to be one of the rare direct evidences for a pearl necklace-like intermediate along the coil-to-globule transition of polyacrylate chains.

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