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Furthermore, there are limits to the formation of uniform coatings on medical devices with complex and elaborate three-dimensional structures due to the low adhesion stability. However, tailoring the degradation period of the biodegradable polymer coating requires careful selection of the polymer type and layer thickness. are used as simple methods for coating a polymer on a metallic material 10, 11, 12, 13. Dip coating, air spraying, electrospraying and spin coating, etc. Among the biopolymers, PCL is produced from the ring-opening polymerization of the cyclic monomer ɛ-caprolactone 9, this polymer has a slower degradation rate than PLLA and has also been applied as a surface coating on magnesium alloys. These biopolymers can be blended, their surfaces can be modified, and the materials can be loaded with growth factors to adjust their bioactivity, mechanical properties, drug release and degradation under physiological conditions. Natural biodegradable polymers such as collagen, polysaccharides like chitosan, and synthetic biodegradable polymers such as polycaprolactone (PCL) and poly-L-lactide (PLLA) provide good protection and have exhibited biocompatibility on Mg 6, 7, 8. The important requirements for the coating to achieve the desired performance are uniformity, lack of porosity, biocompatibility and self-healing ability 4, 5. This difference was due to the high corrosion resistance, which provided sufficient time for bone healing and promoting new bone growth.īiodegradable polymer coatings on magnesium (Mg) and its alloys improve the corrosion resistance of implants in the body over the long term and improves the biocompatibility of metallic Mg in biodegradable applications 1, 2, 3. Denser and thicker bone formed around the PCL-coated screw in rat femur. The 6 wt.% + 4 cycles group had a high corrosion resistance due to the low wear on the thread. In the case of the non-uniform PCL layers, oxides and gases were present between the Mg and the PCL layer because internal magnesium corrosion and the layer peel off. Among various the PCL coating conditions of 2 ∼6 cycles with 5 ∼7 wt.% concentrations, the 6 wt.% + 4 cycles group was applied uniformly to the screw thread. In this study, the optimal conditions for producing a polymer coating on a screw were determined by varying the concentration of the PCL and the coating cycles, and were examined in vitro and in vivo. However, when a complex-shaped material such as a screw is implanted in a bone, the surface coatings are locally damaged, and the protective role of the coating is not sufficiently maintained. In addition, plasma electrolytic oxidation (PEO) is performed to increase adhesion between the polymer and the metal. A polymer coating as polycaprolactone (PCL) is applied to improve the initial corrosion resistance of biodegradable magnesium.