<scp>4D‐</scp>printed <scp>TPU</scp>‐based magnetorheological elastomer using simplified feedstock preparation

Abstract Magnetorheological elastomers (MRE) show promise in creating adaptive, multifunctional materials, especially with advances in 4D printing. Preparing MRE feedstock has typically involved complex processes and multiple thermal treatments, which can degrade material quality. This study simplifies feedstock preparation by using tetrahydrofuran (THF) as a solvent for fused granulate fabrication (FGF) 3D printing, ensuring uniform dispersion of carbonyl iron particles (CIP) in a thermoplastic polyurethane (TPU) matrix. Printed samples were characterized for thickness, diameter, and hardness, confirming dimensional consistency and increased stiffness with higher CIP content. Microstructural analysis revealed uniform CIP distribution, supporting consistent magnetorheological properties and performance integrity. The rheological properties under strain sweep of the samples were evaluated under varying magnetic fields, which showed a significant increase in storage modulus with increased field strength due to CIP alignment. Additional assessments of rheological properties under current sweep, including the absolute magnetorheological (MR) effect, demonstrated that higher CIP content enhanced the MR effect and sample stiffness. These results indicate that 4D‐printed MREs with simplified feedstock preparation offer tunable properties suitable for adaptive applications, such as soft robotics and vibration control. Integrating MRE with 4D printing advances the creation of magnetically responsive materials with programmable mechanical performance. Highlights Simplification of the complex feedstock preparation process by introducing solvent casting. Elimination of multiple thermal processing steps during feedstock preparation. Achieving uniform carbonyl iron particle distribution within the 4D‐printed TPU matrix. 4D‐printed MRE exhibits similar trends in rheological properties as conventionally fabricated counterparts.