Magneto-Tunable Surface Roughness and Hydrophobicity of Magnetoactive Elastomers Based on Polymer Networks with Different Architectures

In this study, we present experimental investigations of the surface structure and water contact angles of magnetoactive elastomers (MAEs), which are controlled by an external magnetic field. Specifically, we examine how the polymer matrix architecture affects the surface roughness and wettability of MAEs in various magnetic fields. We performed a comparative analysis on MAEs based on a linear polysiloxane network and on a matrix of the same chemical nature containing side-grafted chains. We synthesized a series of magnetoactive elastomers containing 75 wt.% carbonyl iron and varying amounts of a low-molecular-weight plasticizer. Although the magnetorheological effect is higher for traditional linear MAEs, we found that the magnetic response in surface properties is higher for novel MAEs with side-grafted chains. The largest increase in water contact angle was observed in the side-chain MAEs with the highest 60 wt.% plasticizer content: rising from 112° in a zero field to 168° in a 490 mT magnetic field. Water contact angles exhibit greater stability over time for side-chain MAEs, and this stability further increases in the presence of a magnetic field. Our results demonstrate that the architecture of the polymer matrix serves as an effective tool for designing smart, magnetically responsive surfaces.