Designing Multi-Layer Polymeric Nanocomposites for EM Shielding in the X-Band

The past two decades have witnessed rapid progress in the development and application of polymers reinforced with nano-scale constituents (on the order of 100 nm), popularly designated as nanocomposites. The present research work focuses primarily on the EM shielding performance of poly(methyl methacrylate) - multi-walled carbon nanotubes (PMMA - MWCNT) nanocomposites in the electromagnetically polluted X-band. The produced thin polymeric nanocomposite films (on the order of tens to hundreds of micrometers) demonstrate a high level of DC conductivity (approx. 30 S/m) at a moderate filler loading of 3 wt.%. The novelty of the content lies in the fact that relevant electromagnetic design parameters were successfully extracted from conducted electromagnetic interference (EMI) SE waveguide measurements on single-layer nanocomposite films. Subsequently, this knowledge was used to design multiple layered materials with varying arrangements of these individual layers to produce nanocomposites with tailored shielding performance. Such design allows the tuning of the two primal EMI shielding mechanisms: reflectivity and absorption, by varying either the conductivity, sequence or thickness of the individual layers. The EM shielding performance of these multi-layer films was subsequently experimentally verified, and was found to be in good agreement with the theoretical design predictions.