Effect of pH on the electrophoretic deposition of chitosan in different alcoholic solutions

Electrophoretic deposition (EPD) of chitosan coatings was carried out using alcohol (methanol, ethanol and isopropanol)-water mixtures with different contents of acetic acid. EPD rate increased with AA content to the maximum and then decreased with its further addition. EPD rate was higher in smaller molecular size alcohols due to their lower viscosities leading to the higher mobility for protonated chitosan ions. Current density increased during EPD from solutions with higher AA contents due to the enhanced water electrolysis. There were bubbles in the coatings deposited from methanolic, ethanolic and isopropanolic solutions with AA ≥ 0.1, AA ≥ 0.5 and AA ≥ 10 Vol%, respectively, due to the intensive water electrolysis. The coatings deposited from methanolic, ethanolic and isopropanolic solutions with 0.05, (0.05 and 0.1) and 5Vol% of AA, respectively, had the highest corrosion resistance in simulated body fluid (SBF) due to their bubble-free structures.