Development of a mechanically robust silicon-based cross-linking polymer for the sustainable marine antifouling coatings

Silicone-based fouling release coatings (FRCs) have shown great promise as an environmentally friendly antifouling technology, while inferior mechanical properties and insufficient substrate adhesion have hindered their further application. We focused on enhancing the mechanical robustness of silicone-based coating through the synergistic effects of hydrogen bonding, π-π aromatic interaction and covalent bonding. The resulting silicone-based coating displayed a low surface energy of 23 mJ/m² and improved mechanical strength and substrate adhesion, offering values up to 6.4 MPa (9.1 times higher) and 2.87 MPa (25.7 times higher), respectively. Additionally, the modified coating demonstrated a tear strength of 9.8 kN/m and mass loss only about 30 mg after enduring 10,000 wear cycles. Alkoxysilane-functionalized polyethylene glycol and quaternary ammonium salt were grafted into the cross-linking structure to make them anchored to the networks and migrated to the surface layer in seawater without releasing. The coating provided 99.1% antibacterial efficiency and effective antidiatom performance (≤ 11.2 cell/mm²). After a 12-month marine field test, the developed film showed only 20% micro bio-fouling compared to 100% fouling coverage on the PDMS surface. By combining improved mechanical properties with antifouling characteristics, this new multifunctional silicone-based FRC exhibits tremendous potential for sustainable marine antifouling coating application.