Synthesis and physical properties of electromagnetic polypyrrole composites via addition of magnetic crystals

Polypyrrole (PPy) has received great attention as an electrically conducting matrix for electromagnetic composites because of its high conductivity, relatively good environmental stability, and easy synthesis. Magnetic crystals are suitable additives for preparing electromagnetic PPy composites. In the past two decades, a great deal of research work has been done on the synthesis and physical properties of electromagnetic PPy composites owing to their promising electromagnetic properties and various potential applications. PPy composites, in various forms such as powders, films, sheets, tubes and blocks, etc., have been prepared using the four methods of simple blending, electrochemical processing, in situ polymerization and the one-step chemical method. The physical properties including electrical, magnetic, absorbing and absorption properties of electromagnetic PPy composites have been extensively studied. This highlight article provides an up-to-date review on the synthesis methods and physical properties of electromagnetic PPy composites, in which the magnetic crystal additives are either in nano-sized or micro-sized scales. A summary is given for the synthesis approaches and their advantages and disadvantages are clearly displayed. The physical properties of electromagnetic PPy composites are then surveyed as a function of the magnetic crystal content. The electromagnetic PPy composites show not only good electrical and magnetic properties but also promising absorbing and absorption properties. Especially, the composites exhibit better absorbing properties than pure PPy or magnetic additives alone; also, they show high adsorption capacities for fluoride, Cr((VI)), and endocrine disrupting compounds, etc. Finally, our perspectives are provided on the future development of electromagnetic PPy composites through the combination of different magnetic crystal additives and synthesis methods.