Thermomechanical properties of confined magnetic nanoparticles in electrospun polyacrylonitrile nanofiber matrix exposed to a magnetic environment: structure, morphology, and stabilization (cyclization)

Abstract

Electrospun metal oxide–polymer nanofiber composites hold promise for revolutionizing biomedical applications due to their unique combination of electronic and material properties and tailorable functionalities. An investigation into the incorporation of Fe-based nanofillers for optimizing the polyacrylonitrile matrix was conducted, where the systematic and organized arrangement of inorganic components was achieved through non-covalent bonding. These carefully dispersed nanomaterials exhibit the intrinsic electronic characteristics of the polymers and concurrently respond to external magnetic fields. Electrospinning was utilized to fabricate polyacrylonitrile nanofibers blended with Fe₂O₃ and MnZn ferrite nanoparticles, which were thermomechanically, morphologically, and spectroscopically characterized in detail. With the application of an external magnetic field in the course of dynamic mechanical measurements under tension, the storage modulus of the glass transition T_g of PAN/Fe₂O₃ rises at the expense of the loss modulus, and a new peak emerges at ∼350 K. For the PAN/MnZn ferrite nanofibers a relatively larger shift in T_g (from ∼367 K to ∼377 K) is observed, emphasizing that in comparison to Fe₂O₃, Mn²⁺ ions in particular enhance the material's magnetic response in MnZn Ferrite. The magnetic oxide particles are homogenously dispersed in polyacrylonitrile, corroborated by high-resolution scanning electron microscopy. Both nanopowder additions lead to a slight shift of the peak towards larger angles, related to the shrinkage of the polymer. Produced nanofibers with high mechanical and heating efficiency can optimize the influence of the intracellular environment, magnetic refrigeration systems and sensors/actuators by their magnetic behavior and heat generation.