Crystallization kinetics and anisotropic properties of polyethylene oxide/magnetic carbon nanotubes composite films

Magnetic carbon nanotubes (m-CNTs) were tethered with γ-Fe2O3 nanoparticles that were formed via a novel modified sol-gel approach. These nanohybrid materials were readily aligned parallel to the direction of a magnetic field in polyethylene oxide (PEO) matrices under a relatively weak magnetic field. The composite films were characterized by XRD, and the crystallization kinetics of PEO in the presence of m-CNTs was measured by differential scanning calorimetry. The results indicated that the surface-tethered magnetic nanoparticles provided nucleation sites for the PEO crystal growth, while maintaining the spherulitic-shaped crystal morphology. The conductivity of the PEO-m-CNTs composite films increased with increasing m-CNTs content in the polymer matrix. Furthermore, the conductivities parallel to the direction of m-CNT alignment were higher than those in the perpendicular direction, indicating that the alignment of the m-CNTs contributed to the enhancement of the anisotropic electrical properties of the composites in the direction of alignment. The mechanical properties of the samples also show anisotropic behavior similar to that of the electrical properties.