Corrosion protection of photocured coatings containing highly crosslinked SU-8 epoxy resin

In this study, a series of photocured epoxied films (SAU-0, SAU-5, SAU-10 and SAU-15) were prepared and applied to the galvanized steel surface for corrosion prevention. These photopolymers were synthesized via cationic photopolymerization using Doublecure®1172 as a cationic photoinitiator. To discuss the crosslinking effect in these photopolymers, various amounts of multifunctional epoxy resin (SU-8) were added into the photoinitiating formulations. The photoreactivity, thermal, mechanical, and morphology properties of all photopolymers were investigated. The results demonstrated that the inclusion of SU-8 epoxy resin not only increased the crosslinking density but also did not sacrifice the interfacial interaction with steel. Finally, the potential dynamic polarization curve of the coated film was studied to realize its corrosion protection performance. As a result, the SAU-15 based photopolymer film, containing the highest amount of SU-8, exhibits the best corrosion protection value (PI = 99.2%) under testing with a 3 M NaCl solution. Furthermore, the SAU-15 based sample demonstrated good long-term storage stability, retaining over 96% of its original corrosion protection value under ambient air atmosphere and room temperature conditions after 28 days. Additionally, all the samples were immersed in 3 M NaCl solution and seawater for long-term stability testing. Once again, the SAU-15 based sample exhibited the best stability after being immersed in the testing solution for 28 days. This paper introduces a concept of SU-8 based photopolymer for corrosion protection and aims to provide a comprehensive understanding of the organic photocured layer technique and its potential for anticorrosion performance.

Graphical abstract