Efficient electromagnetic interference shielding and radar absorbing properties of ultrathin and flexible polymer-carbon nanotube composite films

Electromagnetic interference (EMI) shielding and radar absorbing properties of flexible and ultra-thin composite film of poly(vinylidene fluoride) (PVDF)-multi-walled carbon nanotubes (MWNT) are reported in this study. A simple acid-treatment of MWNT using dilute nitric acid considerably improved the EMI shielding and radar absorbing properties of PVDF composites. Using composite films of only similar to 100 mu m thick, the shielding effectiveness (SET) for 4 wt% pristine MWNT composites was found to be similar to 32 dB at 10.3 GHz a with specific SET of similar to 1788 dB.cm(2) g(-1); while at the same frequency the SET for only 0.5 wt% acid-treated MWNT composites was similar to 26.5 dB. Absorption was found to be the predominant shielding mechanism and the absorption loss increased with MWNT content. A comparison study revealed that the solution-cast composites exhibited better shielding properties than that of melt-mixed composites. The present study paves the way for better designing of thinner and flexible carbon nanotube composites by altering processing conditions and CNT functionalization for efficient radar absorbing materials.