Synthesis of pH sensitive poly(melamine-formaldehyde) microcapsules containing 8-hydroxyquinoline as a corrosion inhibitor

Corrosion is a worldwide crucial problem that strongly affects industrial environments. One way of preventing the corrosion is with a smart coating that can detect and heal localized corrosion. pH and other electrochemical changes such as oxidation/reduction reactions and releasing metal ions are often associated with localized corrosion, so it is expected that materials that are sensitive to pH and metal ions can be used in corrosion protection or detection applications. 8-hydroxyquinoline is a corrosion inhibitor that is sensitive to metal ions so it can act as corrosion indicator. Therefore in this study, 8-hydroxyquinoline was used as core and (PMF) shell was synthesized by in-situ polymerization. The crosslinker which is used in this polymerization makes pH sensitive bonds in microcapsules structure. The morphology of synthesized microcapsules was investigated using scanning electron microscopy (SEM). Fig.1 shows the microcapsules with rough shells. The core content of the microcapsules was evaluated by the thermal gravimetric analysis (TGA). Fig.2 illustrated the TGA and dTGA diagrams of the microcapsules containing 8-hydroxyquinoline. The synthesized microcapsules can be used in organic coating to control and detect localized corrosion.

Keywords:

pH sensitive Microcapsules , Corrosion inhibitor , poly(melamine-formaldehyde) , in-situ polymerization , self healing coating.