The intermolecular forces induced silicon-polyurea marine anti-fouling coating with ideal mechanical and antibacterial performances

Global demand for coatings with ship anti-corrosion and anti-fouling function is increasing every year. In this study, isocyanate terminated PDMS has been prepared by the reaction of isocyanates with amino groups. 7-amino-4-methylcoumarin (AMC) and 3,4-diaminofurazan (DAF) were chemically grafted onto silicone-based polyurea molecules to obtain anti-fouling coating (PDMS-PU-AMC-x) which exhibits excellent mechanical and anti-fouling properties. The dynamic multi-urea hydrogen bonds within the polymer chains and zinc ions coordination with the urea groups ensure the mechanical strength of the coating. The mechanical properties of the coating can be adjusted by the different molar ratios of two isocyanates for hexamethylene diisocyanate (HDI) and isophorone diisocyanate (IPDI). The silicone and two isocyanates act as soft and hard segments which provide flexibility and mechanical strength, respectively. The tensile strength of the PDMA-PU-AMC-3 achieve 11.8 MPa accompanied with tensile deformation 1073.1% when the ratio of IPDI to HDI is 1:1. The dynamic hydrogen bonds and coordination bonds enable the self-healing efficiency of PDMS-PU-AMC-3 up to 65% after 6 h at 70 °C. The synergistic antibacterial effect of DAF and AMC supplies excellent antimicrobial and antifouling capabilities. This work overcomes the low strength of traditional silicone-based self-healing materials and addresses a new strategy for marine coatings.