Tunable surface roughness and wettability of a soft magnetoactive elastomer

Surface topographical modifications of a soft magnetoactive elastomer (MAE) in response to variable applied magnetic field are investigated. The analysis is performed in situ and is based on optical microscopy, spread optical reflection and optical profilometry measurements. Optical profilometry analysis shows that the responsivity of magnetic field‐induced surface roughness with respect to external magnetic field is in the range of 1 µm/T. A significant hysteresis of surface modifications takes place for increasing and decreasing fields. Investigations of shape of sessile water droplets deposited on the MAE surface reveal that field‐induced topographical modifications affect the contact angle of water at the surface. This effect is reversible and the responsivity to magnetic field is in the range of 20°/T. Despite the increased surface roughness, the apparent contact angle decreases with increasing field, which is attributed to the field‐induced protrusion of hydrophilic microparticles from the surface layer. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46221.