How self-assembled organophosphonic acid monolayers on Ti0.5Al0.5N hard coatings affect the adsorption of polycarbonate melt
The interaction of Ti0.5Al0.5N hard coatings with polycarbonate melt was modified by interfacial octadecyl- (ODPA) and heneicosafluorododecylphosphonic acid (FPA) monolayers. The adsorption and packing density of both organophosphonic acids were analysed based on a combined surface chemical and surface electrochemical approach, which disclosed that the organophosphonic acids form densely packed monolayers on the oxygen containing TiAlN surface. XPS analysis, cyclic voltammetry and surface energy studies were comparatively applied to the bare and modified surfaces. The analysis of the resulting decreased interactions between the coated surfaces and molten polycarbonate by imaging ellipsometry indicated that irreversibly adsorbed interfacial films form during the melt/surface contact, however, the thickness of such films depend on the structure of the surface. In this regards, especially the FPA monolayer was found to most effectively hinder the formation of strongly bound residues of molten polycarbonate observed on the bare TiAlN surface.