Studies on characteristics and corrosion behaviour of chitosan/eudragit RS100 bilayer film coated Ti-6Al-4V

In the present study, implant material Ti-6Al-4V has been coated with eudragit (EU) and chitosan (CH) polymers to enhance surface properties. The deposition of polymer coating has covered the surface cracks to a significant level and the fact has been confirmed by FE-SEM coupled with EDAX wherein the atomic percentage of Ti (99.90%) in non-coated surface has been decreased markedly to 0.42% after coating. Scratch resistance and adhesion power of bilayer coating has been increased as indicated by the higher critical loads Lc₁ (16.71 N), Lc₂ (17.56 N), Lc₃ (17.96 N) when a progressive load of 1 N to 20 N is applied over the coated surface. Further, Electrochemical impedance spectroscopy (EIS) and potentiodynamic-polarization studies have shown that the value of polarization resistance is inversely proportional to the corrosion rate. Thus decrease in the corrosion rate from 107.5×10^-2 (mm year^-1) for the non-coated alloy to 2.88×10^-2 (mm year^-1) for CH/EU coating demonstrated that coating enhanced the corrosion resistance of the alloy in the physiological condition. The in vitro antibacterial test conducted against S. aureus, B. subtilis, P. vulgaris and P. auregenosa has shown a significant inhibition zone of 9 mm, 6 mm, 7 mm and 10 mm, respectively, thus indicating the possible application of the polymeric coating material on the dental implants.