Anticorrosive Performance of Smart Epoxy Coatings With Poly(urea‐formaldehyde) Microcapsules Filled With 5‐Ethylidene‐2‐norbornene

Abstract

In this study, poly(urea‐formaldehyde) (PUF) microcapsules filled with 5‐ethylidene‐2‐norbornene (ENB) were produced via in situ polymerization. The microcapsules were synthesized under nine different conditions, based on a sequential factorial design, and the optimal conditions for their production were determined. Based on this, an experimental evaluation of their anticorrosive action associated with the self‐healing mechanism was conducted by incorporating them into epoxy‐based coatings. These coatings were applied to previously cleaned AISI 1020 steel substrates using the dip‐coating method. Anticorrosive performance was evaluated through immersion corrosion tests in a saline solution, following the simulation of damage via scratching. The results demonstrated satisfactory performance for coatings containing microcapsules synthesized under PUF/ENB 1 and PUF/ENB 9 conditions, which also exhibited more uniform microcapsule dispersion, with mean areas containing corrosion products of 3435 and 7457 µm 2 , respectively, compared to 126 838 µm 2 for the pure epoxy coating. However, even samples that exhibited a high degree of microcapsule agglomeration, a lower mean coating thickness, and more pronounceddelamination after damage (EPOXY_PUF/ENB 2), factors that compromised anticorrosive performance, still demonstrated satisfactory corrosion resistance when compared to the pure epoxy coating. The results obtained indicate the ability of the microcapsules to provide anticorrosive protection through the self‐healing mechanism.