The variations of electro-optical behavior and pH of ellipsoidal molecules unfolding on the oxide surface, whereas, at high hematite ( a-Fe 2 O 3 ) particle suspension are investigated in the PEI adsorption, the formation of a much thicker polymer presence of polyethylenimine ( PEI ) . Suspension stability and layer is suggested due to the development of some loops particle electrophoretic mobility are also followed. Considerable and tails, protruding into the solution (3). shift of pH and the particle isoelectric point are found at ex-Chemical imaging of the single PEI molecules on negatremely low PEI concentrations, indicating that nearly all amino tively charged latex particles is demonstrated in (5) using groups of unfolded PEI molecules contact with the oxide surface. a novel kind of chemical force microscopy. At polymer con-The small polymer layer thickness in stabilized suspension ( from centrations sufficient for saturation of the particles, Akari et electro-optical data) shows ''flattening'' of the PEI molecules even at higher polymer adsorption. Similar electro-optical behav-al.
(5) show very close agreement between solution size of ior of suspensions with either a positive or a negative oxide partithe PEI molecule and its size in the adsorbed state. The cle, saturated with PEI, indicates that the colloid -polymer comthickness of the adsorbed polymer layer is found, however, plex assumes charge characteristics of the polymer. Reduced to be much smaller than the solution size of the PEI molecule counterion mobility, found in both systems, is attributed to coun-(5), which suggests ''flattening'' of the adsorbed compact terion condensation on the polyion surface and, possibly, to con-PEI molecules. Electrostatic interaction between polyelecformational transition in adsorbed low-charged polymer moletrolyte molecules and oppositely charged adsorbent surface cules.