Polyaniline/Fe3O4 as conducting/magnetic polymeric composites

In daily uses, a polymer is generally known as insulator, both electrically and thermaly. For several types of certain polymers, the electrical conductivity can be dramatically improved which can reach more than 10 orders of magnitude. One type of such polymers is polyaniline (PANi). By doping of a strong acid in a process called protonation, PANi’s electrical conductivity  can be enhanced from about 10-8 S/cm to more than 20 S / cm, to be a phase called emeraldine salt. Strong acid (HA) will create a pair of defect H+ – A in PANi’s chain which acts as an electrical charge carrier. With this conductivity value range, PANi has changed from an electrically insulating material becoming a semiconductor. In a further development, allowing also for the blending between PANI and Fe3O4 nanoparticles to form a nanocomposite, one may obtain a conductive/magnetic polymeric composite.  

Protonation process using strong acid, H+A, converting PANI from an emeraldine base to emeralidine salt (conducting phase).


PANi (left) and Fe3O4 (middle) powders were mixed and pressed to be pellets (right)


The electrical conductivity (left axis) and saturation magnetization (right axis) dependence on the content of Fe3O4.