Regulating Diverse Liquid-Solid Interactions on Pre-Structured Magnetoactive Elastomer Surfaces

Magnetoactive elastomers (MAE), consisting of magnetorheological (MR) particles dispersed within soft polymeric matrices, are promising candidates for developing multifunctional systems. In this work, we first prepared the MAE substrates with encoded structures using a pre-structuring magnetic field (B₁) and then characterized how the resulting substrates interacted with liquid droplets under different measurement fields (B₂). By systematically tuning both B₁ and B₂, we uncovered the significant role of B₁ in controlling the liquid-solid interactions from the following three perspectives. First, the structure of MR particles encoded by B₁ enhanced magneto-hydrophobicity and even achieved superhydrophobicity on the surfaces of MAE. Second, droplets impacting on these pre-structured MAE surfaces manifested diverse fluid behaviours, which are controlled by the interplay between impact speed and B₂. Finally, we also demonstrated the effective magneto-manipulation of liquid droplets and underwater bubbles on these substrates. Our findings show the multifunctionality of soft MAE substrates by exploiting pre-encoded structures, with potential applications in diverse fields.