Effects of surface modification with hydroxyl terminated polydimethylsiloxane on the corrosion protection of polyurethane coating

Abstract

Polyurethane coating was designed to give a hydrophobic property on its surface by modifying it withhydroxyl terminated polydimethylsiloxane and then effects of surface hydrophobic tendency, water transportbehavior and hence corrosion protectiveness of the modified polyurethane coating were examined usingFT-IR/ATR spectroscopy, contact angle measurement and electrochemical impedance test. As results, thesurface of polyurethane coating was changed from hydrophilic to hydrophobic property due primarily toa phase separation tendency between polyurethane and modifier by the modification. The phase separationtendency is more appreciable when modified by polydimethylsiloxane with higher content. Water transportbehavior of the modified polyurethane coating decreased more in that with higher hydrophobic surface property. The decrease in the impedance modulus |Z| at low frequency region in immersion test for polyurethanecoatings was associated with the water transport behavior and surface hydrophobic properties of modifiedpolyurethane coatings. The corrosion protectiveness of the modified polyurethane coated carbon steel generallyincreased with an increase in the modifier content, confirming that corrosion protectiveness of the modifiedpolyurethane coating is well agreed with its water transport behavior.