Electrospun polyvinylpyrrolidone fibers with high concentrations of ferromagnetic and superparamagnetic nanoparticles.

Electrospun polymer fibers were prepared containing mixtures of different proportions of ferromagnetic and superparamagnetic nanoparticles. The magnetic properties of these fibers were then explored using a superconducting quantum interference device. Mixed superparamagnetic/ferromagnetic fibers were examined for mesoscale magnetic exchange coupling, which was not observed as theoretically predicted. This study includes some of the highest magnetic nanoparticle loadings (up to 50 wt%) and the highest magnetization values (≈ 25 emu/g) in an electrospun fiber to date and also demonstrates a novel mixed superparamagnetic/ferromagnetic system.