Microencapsulation of a phosphonate inhibitor into porous alumina-based carriers

• V.A. Shchelkov¹, S.A. Sidorova², V.L. Demin^1,2, S.A. Tyurina² and N.A. Rashutin²

¹ Frumkin Institute of Physical Chemistry and Electrochemistry Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia
² MIREA – Russian Technological University, 78 Vernadsky Ave., 119454 Moscow, Russia

Abstract: Microencapsulation of corrosion inhibitors makes it possible to increase the efficiency of modifying polymer composite coatings by improving their long-term corrosion resistance. The selection of an inert carrier, which constitutes a solid base for a functional particle, remains an urgent task. This paper examines the characteristics of solid carriers of functional additives used to prepare microcapsules. A series of microcapsules based on a phosphonate inhibitor and aluminum oxide in various forms (Al₂O₃, activated Al₂O₃, and electrocorundum) were received. Using SEM-EDS, it was demonstrated that a polymer shell was successfully formed on the Al₂O₃ and activated Al₂O₃-based microcapsules. By studying the stability of colored solutions in various environments, it was proven that the spectrophotometric method for the quantitative determination of phosphonates is applicable for research in dynamics. The kinetics of the release of the inhibitory agent from microcapsules was studied by a spectrophotometric method using a calibration graph and introducing a correction for the discoloration of the colored solution. Phosphonates were successfully released from the polymer shell of the microcapsules, suggesting that the resulting functional particles are suitable for anti-corrosion modification of protective polymer coatings. It was found that activated aluminum oxide exhibited the highest loading capacity for the inhibitory agent and the longest release time among the carriers considered, due to its highly developed surface.

Keywords: microencapsulation technology, modification of polymer coatings, corrosion inhibition, corrosion, scale formation, paints and varnishes

Int. J. Corros. Scale Inhib., 2025, 14, no. 4, 1931-1941
doi: 10.17675/2305-6894-2025-14-4-11

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