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Recently a great interest has been expressed in electrophoretic deposition (EPD) of polymers, both as particles and as chains. It is generally accepted that also for polymer particles, the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory is valid, therefore, in principle, polymer suspensions suitable for EPD could be easily obtained by dispersing polymer particles in an aqueous or nonaqueous medium. Nevertheless, this work demonstrated that in order to obtain good quality deposits based on poly(ether ether ketone) (PEEK) and poly(tetrafluoroethylene) (PTFE), some additives have to be used. In the case of PEEK, a dispersant providing citrate anions was successfully used, whereas for PTFE a steric suspension stabilization was reached by adding polyvinylpyrrolidone (PVP). In such a way, codeposition of PEEK and PTFE was achieved. The efficiency of the EPD process was demonstrated by means of differential scanning calorimetry (DSC) measurements. A thermal program consisting of heat/cool/heat cycles at a low rate was used in order to evaluate the crystalline amount of each polymer in the deposits. In order to explain the obtained results, it needed to also consider the dimension and structural characteristic of the polymer particles.

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Poly-ether-ether-ketone (PEEK) is a high performance polymer with many intrinsic properties. When it is used in the form of coating, an improvement of some of its functional properties was achieved by forming a surface nanolayer. In this chapter, it will be described how it was possible to obtain this result. Firstly, three kinds of PEEK composite coatings were deposited by electrophoretic deposition, adding alumina particles, polytetrafluoroethylene (PTFE) and lignin to PEEK. Then, the composite coatings were thermal treated in a furnace. Therefore, surface nanostructure and chemical composition of these PEEK composite coatings were modified with respect to bulk coatings, due to interaction between PEEK chain and secondary phase, emphasised by the thermal treatment conditions. Experimental evidence of the formation of surface nanolayer was provided by SEM, TEM, GIXRD, ATR-FTIR and XPS characterisations. Functional characterisations demonstrated that wear resistance-in the presence of alumina particles-hydrophobicity-in the presence of PTFE-and corrosion resistance-in the presence of Lignin-were increased with respect to pure PEEK.