Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Charged Soft Matter

CPP 6.8: Vortrag

Montag, 14. März 2011, 16:15–16:30, ZEU 160

Formation of complexes between linear and spherical polyelectrolytes — Ute Böhme and •Ulrich Scheler — Leibniz-Institut für Polymerforschung Dresden e.V., Hohe Str. 6, 01069 Dresden

Pulsed-field-gradient (PFG) NMR is a versatile tool for the investigation of the hydrodynamic size of molecules and small complexes in solution. In combination with electrophoresis NMR it permits the determination of the effective charge free of any model. PAMAM dendrimers are used as example for spherical weak polyelectrolytes. Their nominal charge is adjusted by the pH-dependent protonation of the amin groups. The protonation is monitored via the chemical shift of adjacent CH2 protons. The effective charge of the PAMAM dendrimers is significantly lower than the nominal charge, which is determined from the protonation of the amino groups. With increasing generation of the dendrimers an increasing fraction of counterions condenses up to 75%. Poly(styrene sulfonate) has been used as a linear strong polyelectrolyte to study the formation of complexes between linear and spherical polyelectrolytes. The fraction of poly(styrene sulfonate), that binds to the dendrimers increases with increasing effective charge of the dendrimer, which is observed in both diffusion and electrophoresis NMR.