Berlin 2001 – wissenschaftliches Programm
Bereiche | Tage | Auswahl | Suche | Downloads | Hilfe
CPP: Chemische Physik und Polymerphysik
CPP 18: Poster: Polymer Blends, Heterogeneous Systems, Colloids and Nanoparticles, Interfaces, Polyelectrolytes
CPP 18.17: Poster
Mittwoch, 4. April 2001, 12:30–15:00, AT1
The Adsorption of Polyelectrolytes to Colloidal Particles monitored by 1H Relaxation of the Solvent — •Bernd Schwarz and Monika Schönhoff — Max-Planck Institute of Colloids and Interfaces, D-14424 Potsdam/Golm
Dilute aqueous solutions of colloidal particles containing varying concentrations of polyelectrolyte are investigated by water 1H relaxation rates R2 obtained from a cpmg-experiment. Due to the fast exchange between free, surface bound and polymer bound water, R2 contains contributions from water in different sites. Differences in water mobility arising due to the particle-polymer interaction are extracted. The adsorption of PAH and PDADMAC to negatively charged polystyrene particles is investigated in dependence of surface coverage: While zeta-potential measurements show a monotonous increase due to the charge reversal of the negatively charged latex, pronounced minima and maxima are found in R2. After confirming that no coagulation occurs, the structures are interpreted as the effects of polymer adsorption on different water populations: The main contributions are the replacement of particle bound water by polymer trains, the immobilisation of polymer bound water due to adsorption, and a condensation of the layer at higher surface coverage. Salt addition during adsorption leads to stronger water immobilisation, which is consistent with findings of a surface coverage.