Ultra-flexible porous magnetorheological elastomers with controllable pore parameters

Flexible responsive materials hold significant potential for vibration control and soft robotics. Magnetorheological elastomers exhibit valuable magnetic-responsive properties, but conventional versions suffer from high stiffness due to magnetic fillers, limiting practical use. Here, we demonstrate a pore-engineering strategy using solvent evaporation to create controllable voids within the elastomer matrix. This reduces the Young’s modulus to just 15% of non-porous equivalents, as voids contribute near-zero stiffness. By spatially tuning void size and density, we fabricate gradient structures with progressively varying modulus. This design significantly enhances material compliance while maintaining magnetic responsiveness. The improved flexibility expands functionality in vibration dampers, soft actuators, and pressure sensors. Our approach establishes pathways for developing adaptable responsive materials, with particular relevance to applications requiring tunable mechanical properties under magnetic fields. Magnetorheological elastomers have useful magnetic-responsive properties, but often suffer from high stiffness due to magnetic fillers. Here, a pore-engineering approach achieves a Young’s modulus 15% of the value for the non-porous equivalent, allowing gradient structures to be synthesized.