Release behavior of pH sensitive microcapsules containing corrosion inhibitor

摘要

A pH sensitive microcapsule (pH-MC) which can be decomposed in corrosive environments on metal substrates was synthesized and its release behavior was investigated. Ester chains which can be hydrolyzed under both alkaline and acidic conditions were successfully introduced into the shell wall of the pH-MC. In separate sets of experiments, cerium nitrate was encapsulated as a corrosion inhibitor, whereas aluminum nitrate was used to investigate the release property due its amphoteric nature. Study of the release behavior with the aluminum nitrate-containing pH-MC (Al-MC) demonstrated that the Al-MCs are sensitive to acidic and basic environments and are inactive in neutral environments. It was also found that hydrolysis of the ester chains occurred prior to release of the core materials. When immersed in an electrolyte with the cerium nitrate-containing pH-MC (CeMC), the open circuit potential (OCP) of a steel substrate showed a nobler potential than when immersed in an electrolyte without Ce-MC.