Study of polymer particles suspensions for electrophoretic deposition.

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.