Highly dispersed crystalline magnetic and conductive polyaniline/iron oxide nanocomposite films

Hybrid materials composed of conducting polymers and magnetic iron oxide nanoparticles (NPs) have an expanding range of novel applications including biomedicine, shielding of electromagnetic interference, sensors, electrochemical capacitors and adsorption of dyes. In this study, we developed highly dispersed, crystalline, magnetic and conductive camphor sulfonic acid protonated polyaniline/iron oxide (PANI-CSA/IO) nanocomposite films from aqueous solution by potentiostatic electrochemical polymerization. The structural, optical, electrical, magnetic and morphological characteristics of the prepared nanocomposite films have been investigated. Interestingly, the crystallization process of the PANI chains led to the dispersion of the IO NPs suppressing their crystallization in the films. It was also observed that the pi-pi* band gap energy of the nanocomposite films increased with increasing the concentration of IO NPs. In addition, almost 2-fold increase in the magnetization of the nanocomposite film was achieved by increasing the concentration of the IO NPs from 3 to 12 wt%. In contrast, the electrical conductivity showed inverse relationship with the IO NPs concentration. This behavior is related to the interplay between a nucleating effect and molecular interaction with the PANI chains of the embedded IO NPs depending on their concentration. At low concentration, the nucleating effect of PANI crystallites is dominant, whereas the molecular interaction takes over at high concentrations. However, the increased presence of the IO NPs hinders the diffusion of the PANI chain segments during crystallization leading to limited crystal growth locally. These findings contribute to the understanding and controlling of the relationship between the self-assembly and physical properties of magnetic NPs/conducting polymer nanocomposite films.