Superhydrophobic and Superparamagnetic Composite Coatings: A Comparative Study on Dual-Sized Functional Magnetite Nanoparticles/Silicone Rubber

In this work, superhydrophobic and superparamagnetic composite coating was prepared by directly dispersing methacryloxypropyl functionalized Fe 3 O 4 @SiO 2 (f-Fe 3 O 4 @SiO 2 ) nanoparticles into silicon rubber (SR) and casting the mixture on the substrate then curing. While single-sized f-Fe 3 O 4 @SiO 2 (~100 nm) was used, it was found that coatings hydrophobicity increased with f-Fe 3 O 4 @SiO 2 content increasing, and coatings surface became superhydrophobic when f-Fe 3 O 4 @SiO 2 content climbed to 50%. In order to further increase the coatings hydrophobicity, dual-sized f-Fe 3 O 4 @SiO 2 (~20 and ~100 nm) were utilized together and the effect of their mutual weight ratio on coatings surface property and morphology was investigated. The experimental results showed that coatings surface water contact angle (CA) could reach the maximum 159.2° at the optimal weight ratio 2/1(wt/wt, ~20/~100 nm). Meanwhile, the coatings remained superparamagnetic and its saturation magnetization was 21.48 emu/g. Based on the coatings surface hydrophobicity test and morphology analysis, the excellent superhydrophobicity should be attributed to the combined result of micro-nano rough structure and low free energy, which derived from the dual-sized f-Fe 3 O 4 @SiO 2 and methacryloxypropyl functional group, respectively. The Fe 3 O 4 @SiO 2 /SR composite coatings are expected to enlarge potential applications in the field of self-cleaning and electromagnetic shielding due to its unique superparamagnetism and superhydrophobicity.