Electrospun Fe3O4-PVDF Nanofiber Composite Mats for Cryogenic Magnetic Sensor Applications

Abstract

Magnetically responsive, mechanically stable and highly flexible iron (III) oxide-polyvinylidene fluoride (Fe3O4-PVDF) piezoelectric composite fiber mats were fabricated via one step electrospinning method for magnetic sensing at cryogenic temperature. The properties of Fe3O4-PVDF composite fiber mats were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, d33 and magnetization test. The fiber diameter decreased as the concentration of Fe3O4 increased. The DSC results suggested a decrease in the crystallinity of the composite fiber mats after adding Fe3O4, and the XRD curves identified that the decrease in crystallinity took place in the β crystalline phases of the fibers. FT-IR results further confirmed the reduction of β phases of the composite fiber mats which dropped the piezoelectric response of the fiber mats by 38% for 5% Fe3O4-PVDF than PVDF fiber but still 400% higher than PVDF pellets. The magnetization test advocated a superparamagnetic state of the fiber at room temperature but a ferromagnetic behavior at a lower temperature. The coercivity values of the mats suggested a homogeneous dispersion of the Fe3O4 nanoparticles into the PVDF matrix. Young’s modulus (E) of the fibers remained the same before and after the magnetization test, indicating the mechanical stability of the fiber in the range of 5 K to 300 K. Its mechanical stability, superparamagnetic behavior at room temperature and ferromagnetic at low temperature could open up its application in spintronic devices at cryogenic temperature and cryogenic power electronic devices.

Investigation of the Morphological Structure of Needle-Free Electrospun Magnetic Nanofiber Mats

“…Moreover, agglomerations of magnetite nanoparticles were detected in the beads using SEM and EDX spectra. Similar to our previous studies [5,22,27], larger amounts of magnetite are detected in the beads than in the nanofibers.…”

“…In this case, the beads The magnetic properties of nanofibers and nanofiber composites are of great interest and the morphology has an influence on the mechanical and chemical properties of the final nanofiber mats. The strategies for an optimal distribution of magnetic nanoparticles are discussed in the literature and various approaches are proposed, such as coating of particles or ultrasonication [20][21][22]. The study by Lalatonne et al notes that conventional mixing methods contribute to particles connecting and aggregating during the formation of the materials due to magnetic dipole and van der Waals interactions [20].…”

“…It was found that agglomerations of magnetic particles negatively affect the mechanical properties [21]. In the study by Chowdhury et al, magnetically responsive, mechanically stable and highly flexible piezoelectric composite fiber mats made of magnetite polyvinylidene fluoride (Fe 3 O 4 -PVDF) were produced in the single-stage electrospinning process and ultrasonication treatment for better dispersion was used [22].…”

Core-Shell Magnetoactive PHB/Gelatin/Magnetite Composite Electrospun Scaffolds for Biomedical Applications

“…Also, after the addition of the Fe 3 O 4 particles in the polymer matrix, the intensity of the peak at 13.6° decreased, which was ascribed to inhibition of the polymer crystallization process caused by the magnetic particles decreasing the volume fraction of the crystalline phase in the fibers [ 35 , 46 ] (for more details please address to the DSC section of this study). Thus, submicron-sized Fe 3 O 4 particles strongly affect the structure of PHB, changing the rate of polymer crystallization, polymer chains mobility and thus limiting the growth of lamellas [ 47 ].…”

Development and Utilization of Multifunctional Polymeric Scaffolds for the Regulation of Physical Cellular Microenvironments

“…In addition, electrospinning has also been shown to mechanically pull the fibers due to the Taylor cone stretching and elongating during the process, further improving piezoelectricity [159]. Chowdhury et al compared the values of d 33 , a piezoelectric coefficient describing how efficiently the material can convert electrical energy to mechanical energy [164]. It was found that electrospun PVDF fiber having a fiber diameter of 105 nm has a significantly higher d 33 value (32 pC/N) as compared to that of PVDF pellet (5 pC/N), demonstrating the potential of electrospinning on the enhancement of the piezoelectric property.…”