Strengthened corrosion control of poly (lactic acid) (PLA) and poly (ε-caprolactone) (PCL) polymer-coated magnesium by imbedded hydrophobic stearic acid (SA) thin layer

To address insufficient corrosion control of polymer-coated magnesium, we apply a hydrophobic stearic acid (SA) thin layer underlying the poly (lactic acid) (PLA) and poly (epsilon-caprolactone) (PCL) coatings on Mg. The SA imbedded polymer-coated Mg showed apparently smaller corrosion current density than the direct-coated counterparts. More importantly, they exhibited manifestly slower and more stable long-term in vitro immersion degradation than the direct polymer-coated Mg up to 21 days. Moreover, the scratch testing disclosed their undercutting corrosion was suppressed evidently. The strengthened corrosion control by the imbedded layer is attributed to its kinetic barrier, hydrophobic nature as well as shielding effect. (C) 2016 Elsevier Ltd. All rights reserved.