Ficus religiosa-inspired microstructure-controlled low surface energy coatings with long-term antifouling effect

Abstract

In general, antifouling coatings based on structural design mostly use the most basic shapes such as cuboids as repeating units. In this study, four kinds of complex surface micro-structured coatings inspired by natural bifacial leaf Ficus religiosa were obtained and applied to the field of marine antifouling coatings. Based on the antifouling mechanism of surface microstructure, SiO2 @PDMS(polydimethylsiloxane)-based Ficus religiosa-like coatings (Gxy, x = D or Z, y = A or I) were prepared by the blending method and the biological template method using the same positive and negative film materials. The antifouling performances of the coatings were evaluated by mussel attachment experiments and diatom attachment experiments. Compared with pure PDMS, the anti-mussel adhesion rate of SiO2@PDMS can be as high as 73.08 %. After 8-day diatom attachment experiments, the SiO2 @PDMS-based and adaxial side-structured negative film (GDI) showed an excellent antifouling performance compared with non-structured sample, and the anti-diatom adhesion rate was 17.96. In addition, a series of surface-modified micro-structured SiO2 @PDMS-based coatings (MGxy, x = D or Z, y = A or I) were prepared from the perspective of low surface energy. The surface energy of MGxy is between 19.62 and 29.95 mJ/m2, and the surface energy after diatom attachment experiment is between 13.51 and 22.23 mJ/m2. The structure, hydrolysis-condensation modification, hydrolysate and the effect of structure on hydrolysate were analyzed by the results of diatom attachment experiment. The importance of structure and the complementary effect of structure and modification on antifouling performance were explained again. Among them, the modified SiO2 @PDMS-based and abaxial side-structured positive film (MGZA) showed the best anti-diatom performance. After 8 days diatom attachment experiment, the anti-diatom adhesion rate of MGZA was as high as 90.78 %. Moreover, the newly discovered microstructural units on GDI and MGZA were parameterized. The results of this study provide insights for further research and long-term application of bionic microstructure and surface modification in the field of antifouling.