One-step electrodeposition of Janus chitosan coating for metallic implants with anti-corrosion properties

Hydrophilic-hydrophobic Janus chitosan coating was facilely fabricated by one-step electrodeposition in HCl/ethanol solvent. The face of chitosan coating attached to the electrode demonstrates a compact structure while the other face away from the electrode demonstrates a porous structure, which endows the chitosan coating asymmetric wettability. The concentration of ethanol has a profound effect on the structure and wettability of the chitosan coating and pioneer work on the corrosion resistance of the chitosan coating on metallic implants was carried out. The growth kinetics of the Janus chitosan coating reveals that the coating grows faster and contains more pores in the presence of ethanol. The anticorrosion properties of the Janus chitosan coating were investigated on common metal implants titanium and 316 L stainless steel. The results show that the Janus chitosan coating obtained with 10 wt% ethanol electrolyte has the best anti-corrosion ability due to its compactness and hydrophobic surface. The corrosion rates of the Janus chitosan coating were reduced to 3.94 × 10−4 mm/yr and 1.77 × 10−2 mm/yr, respectively, significantly improved as comparison to the bare metal corrosion rates (1.46 × 10−3 mm/yr for bare titanium and 3.00 × 10−1 mm/yr for bare stainless steel). The present work provides a simple way to prepare Janus chitosan coating and demonstrates its great potential in implant anticorrosion.