A novel bonding strategy of hydrogel on titanium alloy for marine antifouling engineering: Multiple antifouling mechanisms and DFT calculations

Abstract

Marine biofouling is one of the biggest problems for titanium alloys and rutile TiO2 coatings in marine engineering applications. Hydrogel materials are a novel and environmentally benign antifouling strategy, but they cannot be stabilized on alloy surfaces to provide long-term protection. Focusing on the challenges of bonding at the hydrogel-alloy interface, a PAA/PHEMA composite hydrogel containing Cu2O@PEG powder was strongly bonded to the titanium alloy by forming chemical bonds with APTES. The composite hydrogel still achieves an adhesion strength of 60–70 kPa after 7 days of immersion. The samples maintained a stable copper ion leaching rate of 2.61–3.76 μg·cm−2·d−1 after 21 days of immersion. The coating-modified titanium alloys showed a 100 % bactericidal rate within three hours of contact with different bacteria and exhibited a high anti-algal adhesion rate of up to 99 %. In addition, the attachment mode of APTES on rutile TiO2 was clarified for the first time by Density Functional Theory (DFT) calculations. According to DFT calculations, the adsorption energy of APTES on Ti-TiO2 is −747.025 kJ/mol, and the adsorption energy of acrylic acid on TiO2-APTES is −535.152 kJ/mol. The chemical bonding connection between the hydrogel-alloy interface, as a novel interface bonding strategy, would be expected to broaden the application of titanium alloy in marine engineering.