Graphene Nanoplatelets-Based Lightweight Flexible Nanocomposites for EMI Shielding Application

Abstract

Lightweight, flexible, and thin nanocomposite structures providing enhanced electromagnetic interference (EMI) shielding in the desired frequency band are required for future generations of curved and bendable electronic devices. The present work deals with designing and developing such types of nanocomposite structures based on 2–8 wt% graphene nanoplatelets (GNPs) embedded in the polyurethane matrix. The GNP in the present situation is synthesized through the microwave intercalation technique followed by ultrasonication. It is observed that the 6 wt% of GNP (GNP6) having a density of 0.74 g/cc provides enhanced conductive and dielectric properties in the specified frequency band. The maximum value of total shielding effectiveness ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SE_T</i> ) achieved here is 22.11 dB for GNP6 at 0.35 mm thickness. The strength of the proposed flexible structure is ascertained by measuring the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SE_T</i> of GNP6 after mechanically bending it for 500 cycles. The mechanism contributing to the high <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SE_T</i> is explained based on their microstructure and frequency-dependent dielectric profile. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">SE_T</i> is numerically analyzed by simulation using the CST microwave studio in 8–18 GHz for broadband electromagnetic shielding application. The fabricated lightweight flexible nanocomposite structures show high EMI shielding, making them appropriate for conformal electronic packaging and thin coating in military and space applications.