Ion-Electron-Conducting Polymer Composites: Promising Electromagnetic Interference Shielding Material

摘要

Polymer nanocomposites consisting of poly(vinylidenefluoride-co-hexafluoropropylene) PVdF-HFP, inorganic salt (LiBF4), organic salt (EMIMBF4), multiwalled carbon nanotubes (MWCNTs), and Fe3O4 nanoparticles were prepared as electromagnetic shield material. Improvement in conductivity and dielectric property due to the introduction of EMIMBF4, LiBF4, and MWCNTs was confirmed by complex impedance spectroscopy. The highest conductivity obtained is similar to 1.86 mS/cm. This is attributed to the high ionic conductivity of the ionic liquids and the formation of a connecting network by the MWCNTs facilitating electron conduction. The total electromagnetic interference (EMI) shielding effectiveness has major contribution to it due to absorption. Although the total shielding effectiveness in the K-u band (12.4-18 GHz) of pure ion conducting system was found to be 49 dB and that for the polymer composites which are mixed (ion + electron) conductors is similar to 46 dB, the contributions due to absorption are similar to 16 and similar to 42 dB, respectively.