Synthesis and simultaneous enhancements in electrical and magnetic properties of oriented γ-Fe2O3-nanoneedle/PANI nanocomposite films by cold stretching

The polyaniline (PANI) nanocomposite films with an oriented alignment of γ-Fe2O3-nanoneedles were prepared for the first time via a facile solution evaporation method under an applied magnetic field. The γ-Fe2O3 nanoneedles were coated with PANI in advance to get the uniform dispersion of γ-Fe2O3 nanoneedles in the PANI matrix. The nanocomposite films were then stretched at very low strains at room temperature before doping. It was interesting to notice that the cold stretching could largely enhance both the electrical and magnetic properties of the nanocomposite films. Particularly, the maximum electrical and magnetic properties in both the directions parallel and perpendicular to the stretching direction were obtained at the elastic limit stress level for the stretched nanocomposite films. The enhancements in the electrical and magnetic properties were properly interpreted based on the variances in the morphology, structure and crystallinity degree of PANI matrix.