Frequency selective microwave absorption induced by controlled orientation of graphene-like nanoplatelets in thin polymer films

Abstract

Highly ordered polycarbonate films containing parallel graphite nanoplatelets have been produced by squeezing the corresponding random nanocomposites in the melt. Orientation of the conductive fillers is observed in the plane of the film, i.e., perpendicular to the squeezing direction. It only appears above a critical concentration of 15 wt. % and results from a confinement effect. Oriented samples show a resonance-like sharp increase of the conductivity at a given frequency in the microwave region, with the possibility to control the value of this frequency and the resulting absorption by changing the nanoplatelets concentration. Above this frequency, the oriented polymer nanocomposites show a high level of electromagnetic absorption, which opens the possibility to tailor materials with effective electromagnetic interference shielding by absorption in selected frequency ranges. The in-plane stacking of conductive nanoplatelets separated by insulating polymer induces their strong capacitive coupling to the signal propagating in the plane of the polymer film. As a result, the equivalent circuit of this propagation becomes a resonant system composed of capacitors, inductors, and resistors, which agrees well with the experimental results.

Gas barrier performance of graphene/polymer nanocomposites

“…Numerous attempts have been made to improve graphene exfoliation in polymer matrices. [80][81][82][83][84][85][86][87][88][89][90][91][92][93][94] Most graphene/polymer nanocompoistes have been developed using three strategies: solution mixing, melt mixing and in situ polymerization.…”

Microwave shielding enhancement of high-transparency, double-layer, submillimeter-period metallic mesh

“…With the development of wireless microwave electronic devices, electromagnetic interference (EMI) shielding has become an important issue. [1][2][3][4] Many methods have been proposed to achieve EMI shielding by reflection or absorption. [1][2][3][4][5] In many cases, visibly transparent EMI shielding has been of particular concern.…”

“…[1][2][3][4] Many methods have been proposed to achieve EMI shielding by reflection or absorption. [1][2][3][4][5] In many cases, visibly transparent EMI shielding has been of particular concern. 4-6 Inductive, square, metallic meshes, or metallic grids with submillimeter periods are widely used as high-pass filters to transmit optical bands (from visible to infrared) and reflect low-frequency microwave bands.…”

Highly Efficient Wideband Microwave Absorbers Based on Zero-Valent Fe@γ-Fe2O3 and Fe/Co/Ni Carbon-Protected Alloy Nanoparticles Supported on Reduced Graphene Oxide

“…Indeed, the MNPs allow adjusting the system’s magnetic permeability ( μ r ), while the nanocarbons’ electrical properties can be exploited to easily vary the system’s electrical permittivity ( ε r ), as we previously demonstrated [13]. Consequently, this synergic assembly of the MNPs and NcS individual EM features allow tuning an EMI shielding material’s absorption capabilities [14,15,16].…”