Anisotropic reinforcement in polymer nanocomposites using dielectric-magnetic difunctional fibers

Abstract

One-dimensional (1D) functional fibers have been widely used for the property enhancement of polymer nanocomposites. Modulating the orientations of fibers is crucial to maximizing the performances of the nanocomposites. In this work, we report anisotropic polymer nanocomposites enabled by dielectric-magnetic difunctional ceramic fibers, where the magnetic Fe2O3 nanoparticles (FO nps) were confined inside the dielectric ceramic fibers, to produce concurrent strong magnetism and high dielectric/piezoelectric responses. The difunctional fibers can rotate well along the direction of the external magnetic field during the nanocomposite processing, producing notable anisotropic enhancements of polymer nanocomposites. By computing the difference in magnetic and gravitational potential energy versus the internal thermal energy of the fibers that serve the alignment, we determined the optimal content of magnetic FO nps for producing a desirable alignment of fibers, while maintaining the high insulativity of nanocomposites. Finally, the resultant anisotropic polymer nanocomposites with aligned fibers present a maximum 85% enhancement in dielectric constant (ϵr) and 50% enhancement in piezoelectric coefficient (d33), compared to the nanocomposites with random fibers, while maintaining excellent elastic modulus and transmittance. Our work provides an effective strategy for the development of fiber-reinforced polymer nanocomposites with anisotropy and multi-functionality.