Development of FDM ‐Printed Bio‐Based TPU / CNT / Fe 3 O 4 Nanocomposites for Potential Wearable Applications

The integration of multifunctional thermoplastic polyurethane into additive manufacturing offers new opportunities for advanced elastomeric functional materials. In this study, bio‐based thermoplastic polyurethane (TPU) nanocomposites were synthesized from polypropylene succinate (PPS), 1,5‐pentamethylene diisocyanate (PDI), and 1,3‐propanediol (PDO), and reinforced with carbon nanotubes (CNTs) and magnetite (Fe 3 O 4 ) nanoparticles via a solvent‐free prepolymer process. FT‐IR confirmed successful polymerization, while FIB‐SEM revealed homogeneous dispersion of the hybrid nanofillers within the TPU matrix. CNTs significantly enhanced melt elasticity and stress transfer, whereas Fe 3 O 4 imparted magnetic responsiveness, resulting in multifunctional hybrid nanocomposites. The storage modulus increased to 27.10 kPa for the TPU/CNT composite and remained at 16.99 kPa after Fe 3 O 4 incorporation, indicating sufficient melt elasticity for stable filament extrusion and FDM printing. The TPU/CNT/Fe 3 O 4 hybrid composite exhibited a 23.8% increase in tensile strength together with enhanced magnetic responsiveness. Furthermore, the composite filaments exhibited stable extrusion, excellent layer fidelity, and high dimensional accuracy during FDM printing, enabling the fabrication of auxetic structures. These results demonstrate that the hybrid bio‐based TPU provides a multifunctional platform integrating mechanical reinforcement, magnetic responsiveness, and additive manufacturability for potential flexible wearable applications.