Fabrication of Liquid Metal Composite Ionic Liquid Hydrogels for Antifouling Application

Marine biofouling remains a major challenge for maritime industries, driving the need for low‑toxicity and durable antifouling coatings. Herein, we present a composite hydrogel coating (IL-GLM@Gel) constructed by integrating gallium-based liquid metal (GLM) nanodroplets and a halogenated ionic liquid ([Bmim]·ZnCl2) within a poly(acrylamide-co-acrylic acid) hydrogel matrix. The GLM nanodroplets were first uniformly dispersed and immobilized within the hydrogel via in situ polymerization, followed by solvent exchange to introduce the ionic liquid. The resulting IL-GLM@Gel coating exhibits a densely crosslinked network structure, as indicated by SEM, and demonstrates outstanding synergistic antifouling properties. It achieves antibacterial rates of 96.6% against E. coli and 99.2% against S. aureus, along with algal removal rates of 90.6% for Dunaliella and 98.1% for Porphyridium. The enhanced performance is attributed to the combined effects of Ga3+-induced oxidative stress and the membrane disruption caused by the imidazolium cations. Furthermore, the coating displays environmental stability, including a low water swelling ratio (3.7%), tunable mechanical properties (tensile stress up to 0.36 MPa for Fe3+-based IL and strain up to 957% for Zn2+-based IL), superior water retention, and a low friction coefficient of 0.045. Overall, this work presents a promising strategy for the design of high-performance, multifunctional hydrogel coatings for potential long-term marine antifouling applications.