Shape investigations of charged block copolymer micelles on chemically different surfaces by atomic force microscopy

In the present paper, shape transitions of charged diblock copolymer micell es of Poly(ethylethylene-b-styrene sulfonic acid) (PEE-PSSH) were studied b y dynamic scanning force microscopy (SFM) above the glass transition temper ature of the polymer. Changing the ionic strength in the applied solution i nduced shape transitions from spherical micelles to network-like structures and/or spherical vesicles have been observed. The adsorption behavior of t he structures was studied on different chemical surfaces. Neutral (Graphite ) as well as positively charged (Polyethylenimine- and MgCl2-modified) mica surfaces were applied for this purpose. The adsorption structures of the m icellar aggregates on a substrate is strongly influenced by the chemical mo dification of the surface. The formation of vesicles on positively charged surfaces from vesicle free solutions could also be observed.