IMPROVING MAGNESIUM’S CORROSION RESISTANCE THROUGH TANNIC ACID-POLYETHYLENEIMINE COATING FOR BIORESORBABLE IMPLANT APPLICATIONS

• Main Author: Daniel
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/66161
• Institution: Institut Teknologi Bandung

The high corrosion rate of magnesium limits its application as a bioresorbable implant, despite its good biocompatibility. The tannic acid (TA) coating on magnesium has succeeded in increasing the corrosion resistance of magnesium, although the presence of cracks in this coating still limits its effectiveness. This research focuses on the effect of adding polyethyleneimine (PEI) as a crosslinker agent to TA to increase the corrosion resistance of magnesium and its biocompatibility. TA-PEI coating on magnesium with TA:PEI weight ratio 1:0, 1:0.5, 1:1, and 1:2 which was synthesized by the immersion method was evaluated by characterizing the composition, morphology, structure and surface roughness of the coating as well as the deformation mechanism. Immersion and electrochemical corrosion tests (Tafel and Electro Impedance Spectroscopy / EIS) were carried out to determine the corrosion properties and corrosion rate of the material. Wettability and cell adhesion tests were carried out as a coating biocompatibility test. The TA-PEI coating was successfully deposited on the magnesium surface and was able to increase the corrosion resistance and biocompatibility of magnesium. The increase in PEI content from the weight ratio of TA:PEI 1:0 to 1:2 resulted in a reduction in areal crack density from 25.49% to 7.12%, coating thickness increased from 5.7 ?m to 9.3 ?m, surface roughness decreased from 5.20 ?m to 0.98 ?m, but changed deformation mechanism from ductile to brittle. The addition of PEI to TA as a pure magnesium coating has succeeded in increasing the corrosion resistance of the material. Changes in the weight ratio of TA:PEI 1:0 to 1:2 is the most optimum ratio because it can reduce the corrosion rate of the material from 3.7 mm/y to 0.47 mm/y. Formation of hydroxyapatite on corroded material indicates this system is biocompatible. Increasing the PEI content from the 1:0 to 1:2 TA:PEI weight ratio decreased the contact angle from 74° to 24°. At 1:2 TA:PEI ratio, passage 6 HWJ cells can adhere well. Both indicate that this coating system has good biocompatibility for human physiochemical systems