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Seawater-degradable self-polishing epoxy coatings
Researchers have developed a novel epoxy resin that degrades in seawater, creating a self-renewing surface with strong anti-fouling properties.
A Chinese research team has introduced a new type of self-polishing anti-fouling coating based on epoxy resin. Unlike conventional systems based on thermoplastic acrylics or polyurethanes, the new formulation uses a specially designed seawater-degradable epoxy resin (DIGE) containing a pyrrolidone structure.
By blending DIGE with commercial epoxy resin (E51) in various mass ratios, both the degradation rate and antifoulant release can be precisely controlled. Hydrolysis of the pyrrolidone structure in mildly alkaline conditions increases the material’s hydrophilicity and accelerates the breakdown of neighbouring ester bonds, resulting in a continuously self-renewing, clean surface that inhibits bio-fouling.
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Strong mechanical performance and antibacterial activity
Surface analyses under artificial seawater conditions showed gradual erosion of the coating over several weeks. Even after two months of hydrolysis, DIGE-EP coatings achieved bactericidal rates of 99.7 % against E. coli and 99.9 % against S. aureus.
In addition to antifoulant release from within the resin matrix, the resin’s intrinsic anti-fouling property contributes to this effect. β-Amino alcohol groups formed in-situ during curing provide good hydrophilicity. The coatings also showed high mechanical performance, with adhesion exceeding 8 MPa and impact strength reaching 90 kg·cm, meeting the requirements for long-term use.
Source: Li, J. et al., Sea-water degradable self-polishing epoxy thermosets for anti-fouling coatings. Prog. Org. Coat. 203, 109162 (2025).
