AC electrophoretic deposition of organic–inorganic composite coatings

[Display omitted] ► Successful deposition of PAA–TiO2 composite coatings using alternating current electrophoretic deposition (AC-EPD). ► Bubble formation in the coatings avoided when using alternating fields during EPD. ► Polymer–ceramic composite coatings are attractive as soft coatings for orthopedic devices. Alternating current electrophoretic deposition (AC-EPD) of polyacrylic acid (PAA)–titanium oxide (TiO2) nanoparticle composites on stainless steel electrodes was investigated in basic aqueous solution. AC square wave with duty cycle of 80% was applied at a frequency of 1kHz. FTIR–ATR spectra showed that both AC and direct current (DC) EPD successfully deposited PAA–TiO2 composites. The deposition rate using AC-EPD was lower than that obtained in direct current DC-EPD. However, the microstructure and surface morphology of the deposited composite coatings were different depending on the type of electric field applied. AC-EPD applied for not more than 5min led to smooth films without bubble formation, while DC-EPD for 1min or more showed deposits with microstructural defects possibly as result of water electrolysis. AC-EPD was thus for the first time demonstrated to be a suitable technique to deposit organic–inorganic composite coatings from aqueous suspensions, showing that applying a square wave and frequency of 1kHz leads to uniform PAA–TiO2 composite coatings on conductive materials.