Berlin 2005 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 30: POSTER: Chemical physics

CPP 30.50: Poster

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

pH-Dependent Aggregation Behaviour of Polypeptide-Polybutadiene Block-Copolymers in Aqueous Solution — •Reinhard Sigel, Magdalena Losik, and Helmut Schlaad — Max-Planck-Institut of Colloids and Interfaces, Am Mühlenberg 1, D-14476 Golm

Block-Copolymers composed of 1,2-polybutadiene-block-poly(L-lysine) (PB-b-PL) form aggregates in saline aqueous solution because of the insoluble PB-block. The soluble PL block is changed from a random coil to a helix by varying the solution pH value. This conformational switching is expected to change also the aggregation properties of the polymer. Unfortunately, dynamic light scattering measurements show a strong and curved dependency of the diffusion constant on the scattering angle, which renders a standard data analysis impossible. The phenomena is interpreted as an inhomogeneous distribution of the aggregates in the highly dilute solution, which is caused by weak but long range attractive interactions. In regions with high concentration, the effect of the structure factor and the hydrodynamic mobility function on the diffusion become important. A data analysis including these effects is discussed.