Polypyrrole magnetic composites

As microwave absorption is combined effect of dielectric and magnetic losses along with finite conductivity and matching thickness therefore, efforts have also been made to fine time these parameters. For example, Li and co-workers [153] synthesized polystyrene polypyrrole nickel (PSi PPy Ni) composite microspheres. These composites with ferromagnetic behavior display maximum R value of -20 dB at 10.69 GHz. 

Of all known intrinsically conducting polymers, polypyrrole is probably the one most frequently used in commercial applications, mainly due to the long-term stability of its conductivity and to the possibility of forming homopolymers or composites with optimal mechanical properties [1-5]. The preparation of soluble and processible polypyrroles, with an additional improvement in atmospheric stability, makes these materials serious candidates for use in technological applications, for example, for antistatic or magnetic shielding coatings [6-8], sensors and actuators [9-11], batteries [12-14], and molecular devices or modified electrodes [15-18]. 

Aleshin, A. N., Mironkov, N. B., Suvorov, A. V., Conklin, J. A., Su, T. M., and Kaner, R. B., Electrical properties of ion implanted and chemically doped polyaniline films, in Materials Research Society Symposium Proceedings on Electrical, Optical and Magnetic Properties of Organic Solid State Materials III, Vol. 413, 1996, p. 609. Cameron, D. A., and Reynolds, J, R., Conducting molecular composites of polypyrrole with electroactive polymeric dopant ions, ACS Proc., 37, 684 (1996). 

In the last few years investigations have centered mainly on the improvement of the physical properties of polypyrroles, such as processability, stability or mechanical integrity. Thus soluble polypyrroles are now available and several techniques, such as blend or composite formation, are being optimized in order to prepare processable materials which can be used and processed like common polymers. Those possibilities, as well as the improvement in atmospheric stability of polypyrroles, make these materials serious candidates for use in specific technological applications, such as antistatic or magnetic shielding coatings, sensors and actuators, batteries, molecular devices or modified electrodes. 

Xu Z, Gao M, Yu L et al (2014) Co nanoparticles induced resistive switching and magnetism for the electrochemically deposited polypyrrole composite films. ACS Appl Mater Interfaces 6 17823-17830... 

Cabrera L, Gutierrez S, Morales MP et al (2009) Magnetic conducting composites based on polypyrrol and iron oxide nanoparticles synthesized via electrochemistry. J Magn Magn Mater 321 2115-2120... 

Conductive magnetic materials are usefiil in the fabrication of sensors and devices.They consist of magnetic nanoparticles in a conductive polymer matrix. A charge transfer can be estabUshed between the particle surface and the polymer, so that the material acts as a united electronic system. Some proposed compositions are magnetite-polyanyline, maghemite-polypyrrole, cobalt ferrite- polypyrrole, and several metal-polymer combinations." ... 

---