@article{654, abstract = {Magnetic nanofibers are of great interest in basic research, as well as for possible applications in spintronics and neuromorphic computing. Here we report on the preparation of magnetic nanofiber mats by electrospinning polyacrylonitrile (PAN)/nanoparticle solutions, creating a network of arbitrarily oriented nanofibers with a high aspect ratio. Since PAN is a typical precursor for carbon, the magnetic nanofiber mats were stabilized and carbonized after electrospinning. The magnetic properties of nanofiber mats containing magnetite or nickel ferrite nanoparticles were found to depend on the nanoparticle diameters and the potential after-treatment, as compared with raw nanofiber mats. Micromagnetic simulations underlined the different properties of both magnetic materials. Atomic force microscopy and scanning electron microscopy images revealed nearly unchanged morphologies after stabilization without mechanical fixation, which is in strong contrast to pure PAN nanofiber mats. While carbonization at 500 °C left the morphology unaltered, as compared with the stabilized samples, stronger connections between adjacent fibers were formed during carbonization at 800 °C, which may be supportive of magnetic data transmission.}, author = {Fokin, Nadine and Grothe, Timo and Mamun, Al and Trabelsi, Marah and Klöcker, Michaela and Sabantina, Lilia and Döpke, Christoph and Blachowicz, Tomasz and Hütten, Andreas and Ehrmann, Andrea}, issn = {1996-1944}, journal = {Materials}, keywords = {ferrimagnetic materials, superparamagnetism, magnetic hysteresis, magnetic materials, magnetic nanoparticles, nanocomposites, nanowires}, number = {7}, title = {{Magnetic Properties of Electrospun Magnetic Nanofiber Mats after Stabilization and Carbonization}}, doi = {10.3390/ma13071552}, volume = {13}, year = {2020}, } @article{629, abstract = {Electrospinning can be used to create nanofibers from diverse polymers in which also other materials can be embedded. Inclusion of magnetic nanoparticles, for example, results in preparation of magnetic nanofibers which are usually isotropically distributed on the substrate. One method to create a preferred direction is using a spinning cylinder as the substrate, which is not always possible, especially in commercial electrospinning machines. Here, another simple technique to partly align magnetic nanofibers is investigated. Since electrospinning works in a strong electric field and the fibers thus carry charges when landing on the substrate, using partly conductive substrates leads to a current flow through the conductive parts of the substrate which, according to Ampère’s right-hand grip rule, creates a magnetic field around it. We observed that this magnetic field, on the other hand, can partly align magnetic nanofibers perpendicular to the borders of the current flow conductor. We report on the first observations of electrospinning magnetic nanofibers on partly conductive substrates with some of the conductive areas additionally being grounded, resulting in partly oriented magnetic nanofibers.}, author = {Storck, Jan Lukas and Grothe, Timo and Mamun, Al and Sabantina, Lilia and Klöcker, Michaela and Blachowicz, Tomasz and Ehrmann, Andrea}, issn = {1996-1944}, journal = {Materials}, keywords = {electrospinning, magnetic nanofibers, magnetite, magnetic field lines, Ampère’s right-hand grip rule, Maxwell equations}, number = {1}, title = {{Orientation of Electrospun Magnetic Nanofibers Near Conductive Areas}}, doi = {10.3390/ma13010047}, volume = {13}, year = {2019}, } @article{633, abstract = {Conductive nanofiber mats can be used in a broad variety of applications, such as electromagnetic shielding, sensors, multifunctional textile surfaces, organic photovoltaics, or biomedicine. While nanofibers or nanofiber from pure or blended polymers can in many cases unambiguously be prepared by electrospinning, creating conductive nanofibers is often more challenging. Integration of conductive nano-fillers often needs a calcination step to evaporate the non-conductive polymer matrix which is necessary for the electrospinning process, while conductive polymers have often relatively low molecular weights and are hard to dissolve in common solvents, both factors impeding spinning them solely and making a spinning agent necessary. On the other hand, conductive coatings may disturb the desired porous structure and possibly cause problems with biocompatibility or other necessary properties of the original nanofiber mats. Here we give an overview of the most recent developments in the growing field of conductive electrospun nanofiber mats, based on electrospinning blends of spinning agents with conductive polymers or nanoparticles, alternatively applying conductive coatings, and the possible applications of such conductive electrospun nanofiber mats.}, author = {Blachowicz, Tomasz and Ehrmann, Andrea}, issn = {1996-1944}, journal = {Materials}, keywords = {electrospinning, conductive nanofibers, conductive solution, conductive polymers, conductive coating}, number = {1}, title = {{Conductive Electrospun Nanofiber Mats}}, doi = {10.3390/ma13010152}, volume = {13}, year = {2019}, }