Composites of polypyrrole with conducting and ferromagnetic behaviors

Composites of polypyrrole (PPy) with electrical and ferromagnetic behaviors were synthesized by a chemical method in the presence of p-dodecylbenzene sulfonic acid sodium salt (NaDS) as a surfactant and dopant. The magnetic p roperties of the resulting composites showed ferromagnetic behavior, such a s high saturated magnetization (M-s = 9.06-43.7 emu/g), and coercive force (H-c = 9-57 Oe). The saturated magnetization linearly increased with increa ses in the Fe content. No influence of the counterion on this relationship was observed. The conductivity of the composites at room temperature depend ed on the counterion and doping degree. The highest conductivity of 10(0) S /cm was achieved under the optimal synthetic conditions. A structural chara cterization by elemental analysis, Fourier transform infrared, and X-ray di ffraction proved that nanometer-sized (16-20-nm) iron oxide (Fe3O4) in the composites was responsible for the ferromagnetic behavior of the composites , whereas the high conductivity of the composites contributed to the diffic ult deprotonation of the doping PPy with DS- counterion in a basic reaction medium. (C) 2000 John Wiley & Sons, Inc.