Electrophoretic deposition of hydroxyapatite–chitosan nanocomposite coatings in different alcohols

Electrophoretic deposition (EPD) method was used to prepare hydroxyapatite (HA)–chitosan nanocomposite coatings on 316L stainless steel from alcoholic (methanol, ethanol and isopropanol) suspensions containing 0.5 g/L chitosan and 2, 5 and 10 g/L HA. Electrophoretic mobility of HA nanoparticles was raised by decreasing the molecular weight of alcohol, so the deposition rate of methanolic suspensions was the highest. FTIR, TG/DTA and SEM analyses were used to investigate the coatings properties. Chitosan incorporated in HA-chitosan coatings by two mechanisms: the chitosan adsorbed on the HA nanoparticles and incorporated in the coatings accompanying them, and the non-adsorbed chitosan deposited by EPD method. The chitosan incorporated in the coatings by adsorption on HA nanoparticles increases and the chitosan incorporated in it by EPD decreases with increasing the molecular weight of alcohol. The coating deposited from ethanolic suspension containing 0.5 g/L chitosan and 5 g/L HA had the highest corrosion resistance in simulated body fluid environment at 37 °C.