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Superhydrophobic surfaces are of great interest because of their remarkable properties. Due to its maximal hardness and chemical inertness, diamond film has great potential in fabricating robust superhydrophobic surfaces. In the present study, an oxygen-terminated polycrystalline boron-doped diamond (O-PBDD) superhydrophobic surface with micro/nano-hierarchical porous structures is developed. The preparation method is very simple, requiring only sputtering and dewetting procedures. The former involves sputtering gold and copper particles onto the hydrogen-terminated polycrystalline boron-doped diamond (H-PBDD) to form gold/copper films, whereas the latter involves placing the samples in an atmospheric tube furnace to form hierarchical pores. By controlling the etching parameters, the wettability of the O-PBDD surface can be adjusted from hydrophilic to superhydrophobic, which is significantly different to the normal hydrophilicity feature of O-termination diamonds. The water contact angle of the obtained O-PBDD surface can reach 165 ± 5°, which is higher than the superhydrophobic diamond surfaces that are reported in the literature. In addition, the O-PBDD surface exhibits excellent durability; it can maintain satisfactory superhydrophobicity even after high-pressure, high-temperature, and sandpaper friction tests. This work provides a new research direction for fabricating robust superhydrophobic materials with diamond film.
RESUMO
[This corrects the article DOI: 10.1039/C9RA06761B.].
RESUMO
Biofouling is a significant maritime problem because the growth of fouling organisms on the hulls of ships leads to very high economic losses every year. Inspired by the soft skins of dolphins, we prepared graphene oxide/silicone rubber composite membranes in this study. These membranes have low surface free energies and adjustable elastic moduli, which are beneficial for preventing biofouling. Diatom attachment studies under static conditions revealed that color has no effect on antifouling behavior, whereas the studies under hydrodynamic conditions revealed that the combined effects of color and elastic modulus determine the antifouling performance. The experimental results are in accordance with the "harmonic motion effect" theory proposed by us, and we also provide a supplement to the theory in this paper. On the basis of the diatom attachment test results, the membrane with 0.36 wt % of graphene oxide showed excellent antifouling performance, and is promising in practical applications. The results confirmed that the graphene oxide and graphene have similar effect to enhance silicone rubber antifouling performance. This study provides important insight for the design of new antifouling coatings; specifically, it indicates that lighter colors and low Young's moduli provide superior performance. In addition, this study provides a reference for the application of graphene oxide as fillers to enhance the composite antifouling performance.
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The influence of elastic deformation and elastic modulus on the release of adhered bacteria was investigated in this paper. Four silicone elastomers (SE) with different elastic moduli and one rigid polystyrene sheet were prepared to verify the antifouling effect of elastic deformation. The SE film has an elastic deformation effect under the stimulus of fluid medium, which makes the surface unstable. That could reduce the adhesion of fouling organisms and provide a foul-release basis. Distinct anti-adhesion properties were observed in our study in that cells more easily adhered to the rigid surface than the elastic surfaces under hydrodynamic conditions. However, the bacterial attachment test showed a similar antifouling performance of SE and the rigid surface under static conditions. To investigate the anti-adhesion ability of the elastic surface and rigid surface, the bacterial adhesive kinetics were studied by Discrete Element Method (DEM)-Computational Fluid Dynamics (CFD) coupling simulation. Results indicated the number of bacteria adhering on the elastic wall was significantly lower than on the rigid wall. And as the elastic modulus increased, the bacterial adhesion increased accordingly within a certain range. This work should not only enhance understanding of elastomer-based antifouling materials, but also facilitate the design and construction of other types non-toxic foul-release materials.
RESUMO
Composite coatings have attracted great attention as an eco-friendly and economic solution to prevent ship hulls from biofouling. Inspired by the unstable surfaces of marine organisms with antifouling properties, this study describes the preparation of graphene-silicone rubber composite membranes. The membranes are characterized by a low surface energy and an adjustable elastic modulus, and these properties are conducive to preventing biofouling. Bacterial attachment was tested under both quasi-static and hydrodynamic conditions, and one rigid polystyrene sheet was used as the control group to verify the antifouling effects of unstable surfaces. The polystyrene sheet and the elastic membranes showed similar antifouling performance under quasi-static conditions. However, under hydrodynamic conditions, the elastic membranes showed better antifouling performance than the rigid polystyrene sheet. The results obtained using a laser-displacement sensor showed that micron-scale deformations were present on the elastic surface, and a mechanical model was employed to verify this conclusion. This study first confirmed the antifouling effects of the unstable surface, and proposed a model to reveal the antifouling mechanism of the unstable surface. According to the bacterial attachment test, a new generation membrane was made showing antifouling capacity with just 0.36 wt% graphene included during the fabrication of the membrane. This study provided a deeper insight into the antifouling mechanism of the elastic surface, and the membrane (0.36 wt%) may be promising for practical applications.
