Dresden 2006 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 5: Polyelectrolytes

CPP 5.2: Talk

Monday, March 27, 2006, 14:45–15:00, ZEU 160

Engineering Heterogeneously Charged Surfaces by Dendrimer Adsorption: Mechanisms and Interaction Forces — •Georg Papastavrou, Ramon Pericet-Camara, Samuel Rentsch, and Michal Borkovec — University of Geneva, Laboratory of Colloid and Surface Chemistry, Science II CHIAM, Quai Ernest Ansermet 30, 1211 Geneva, Switzerland

The adsorption of poly(amidoamine) (PAMAM) dendrimers of generations G8 and G10 to a mica surface has been studied by AFM as function of ionic strength and pH. The observed trends of the surface coverage can be described within the effective hard sphere model for Random Sequential Adsorption (RSA). Surfaces with a well-defined density of dendrimers with different surface coverages ranging from 0.05 up to 0.4 can be prepared by selecting an appropriate dendrimer generation, ionic strength of the background electrolyte, and pH-value. These surfaces, although of random nature, exhibit characteristic length scales in the nanometer range for the distances between neighboring adsorbed dendrimer molecules and the approach can be applied as well to colloidal particles. We present measurements on the interaction forces between such heterogeneously charged surfaces by the colloidal probe technique and examine especially the conditions under which the Derjaguin approximation can be applied in the sphere-sphere geometry.