Sulfur―Quinone Polyurethanes and the Protection of Iron against Corrosion

摘要

A sulfur-quinone diol monomer, 2,5-bis-(2-hydroxyethylthio)-1,4-benzoquinone (SQM-2), was prepared by the reaction of 2-mercaptoethanol with 1, 4-benzoquinone. SQM-2 and polycaprolactone diol (M_n = 1250) were condensed with toluene diisocyanate to give a sulfur-quinone polyurethanes, SQPU-1, containing 7 mole percent SQM-2. SQPU-1 was coated onto an iron square and exposed to either 0.1 M sodium chloride electrolyte or substitute ocean water. Electrochemical impedance spectroscopy monitored any degradation of the coatings and showed that the sulfur-quinone polyurethane protected the iron against corrosion. Reflectance absorption infrared spectroscopy showed that the chemisorbed sulfur-quinone functional group lies parallel to the iron surface.