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Hydrophobically modified amphiphilic polyelectrolyte films derived from poly (maleic anhydride-alt-styrene) containing hydrophobic aryl-alkyl type side chains such as phenyl-ethyl, phenyl-butyl, naphthyl-ethyl and naphthyl-butyl were studied by Kelvin probe force microscopy. These films were adsorbed from polyelectrolyte solutions at 0.001 mol/L and 0.1 mol/L NaCl onto silicon wafers modified with 3-aminopropyltrimethoxysilane. At high ionic strength, the work function was dependent on the hydrophobic character of the side chain. At low ionic strength this behavior was determined by the spacer group in the side chain. The fractal analysis of the films indicated self-affinity surfaces whereas the fractal dimensions of the surface topography follow a similar trend as the electronic work function with the ionic strength. This behavior can be explained by the increasing hydrophobic character of the side chain with naphthyl moieties. Relationship between the molecular structure and the fractal dimensions with the work function of the adsorbed polyelectrolytes was found.

Surface activity of N -monopropyl maleamic acid-alt-styrene (NPMA-alt-S) and N -monodecyl maleamic acid-alt-styrene (NDMA-alt-S) was studied. Surface pressure–area isotherms ( Π – A ) at the air/water interface were determined. It was found that the pH of the water subphase and the chemical structure of the copolymers studied strongly influence the type of isotherms. It was also found that the driving force for the adsorption of NPMA-alt-S, water soluble polymer at the air/water interface arises from an entropic contribution.