Magneto‐Induced Superhydrophobicity and Surface Restructuring in Magnetoactive Elastomers: Plate‐Like Versus Spherical Magnetic Fillers

ABSTRACT Magnetoactive elastomers (MAEs) with tunable surface wettability are promising for adaptive coatings, microfluidics, and soft robotics, yet optimizing their field‐induced topographical response remains challenging. This study systematically investigates the magneto‐responsive wetting behavior of polydimethylsiloxane‐based MAEs filled with spherical carbonyl iron particles versus plate‐like (flake‐like) iron particles with irregular morphology. By varying plasticizer content, filler concentration, and film thickness, we demonstrate that particle morphology critically governs surface restructuring. Plate‐like fillers enable a rapid transition to a high‐adhesion superhydrophobic state at significantly lower plasticizer loadings (25 wt.%) and moderate magnetic fields (400 mT) compared to spherical counterparts, and ultimately reach a maximum water contact angle of 162° ± 2° at 490 mT. This enhancement is driven by the anisotropic demagnetization of plate‐like particles, which promotes in‐plane magnetization and field‐parallel alignment, generating pronounced surface protrusions that trap air and stabilize the Cassie–Baxter wetting regime. Surface roughness increases 2–3 times more for plate‐like composites under field, directly correlating with contact angle enhancement. Furthermore, plate‐like iron based MAEs exhibit superior temporal stability of wettability (< 1° change over 2.5 min at maximum field) and achieve higher absolute storage modulus during magnetic actuation. These results establish filler anisotropy as a powerful, chemistry‐free design strategy for developing robust, magnetically switchable superhydrophobic surfaces with tailored mechanical properties.

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