Shape Investigations of Charged Block Copolymer Micelles on Chemically Different Surfaces by Atomic Force Microscopy

Abstract

In the present paper, shape transitions of charged diblock copolymer micelles of Poly(ethylethylene- b -styrene sulfonic acid) (PEE-PSSH) were studied by dynamic scanning force microscopy (SFM) above the glass transition temperature of the polymer. Changing the ionic strength in the applied solution induced shape transitions from spherical micelles to network-like structures and/or spherical vesicles have been observed. The adsorption behavior of the structures was studied on different chemical surfaces. Neutral (Graphite) as well as positively charged (Polyethylenimine- and MgCl 2 -modified) mica surfaces were applied for this purpose. The adsorption structures of the micellar aggregates on a substrate is strongly influenced by the chemical modification of the surface. The formation of vesicles on positively charged surfaces from vesicle free solutions could also be observed.