pH-responsive smart composite coating with active anticorrosion and efficient scale inhibition properties

In this work, porous polysulfone (PSF) microcapsules were prepared using the method of mixed solvent volatilization, these microcapsules were used as a carrier, 1-hydroxyethylidene-1, 1-diphosphonic acid (HEDP) was used as an active substance for scale and corrosion inhibition, and stearic acid (SA) was used as a coating to prepare a pH-responsive smart microcapsule slow-release filler. Then, the smart microcapsules were added to a polyurea resin to prepare a pH-responsive smart composite coating with anti-corrosion and scale inhibition properties. The results showed that SA/PSF/HEDP microcapsules have significant pH-triggering activity in an alkaline environment. The alkaline supersaturated CaCO3 solution test showed that the composite coating has excellent scale inhibition performance. This is attributed to the in the microcapsules being released to the coating surface, achieving the purpose of complexation and solubilization. Local electrochemical impedance spectroscopic (EIS) proved that the SP/SA/PSF/HEDP composite coating has good corrosion resistance. This is attributed to the release of corrosion inhibitors, which can form a dense protective film on the metal. The scale inhibition efficiency of the composite coating was as high as 78.57 %, and the impedance modulus value is increased by three orders of magnitude.