Mechanical properties of polyelectrolyte multilayer self-assembled films

The mechanical properties of electrostatic self-assembled multilayer films from polyacrylic acid (PAA) and C60-ethylenediamine adduct (C60-EDA) or poly(allylamine hydrochloride) (PAH) were evaluated by atomic force microscopy (AFM) wear experiments. Because of the higher molecular weight of PAH, the wear resistance of the (PAH/PAA)10 film is higher than that of the (PAH/PAA)2(C60-EDA/PAA)8 film; that is, the former is mechanically more stable than the latter. The mechanical stability of both films can be improved significantly by heat treatment, which changes the nature of the linkage from ionic to covalent. The AFM measurement also reveals that the (PAH/PAA)2(C60-EDA/PAA)8 film is softer than the (PAH/PAA)10 film. The friction properties of the heated films were measured. These films can be developed as potential lubrication coatings for microelectromechanical systems.