Flexible, stretchable and lightweight polyurethane and graphene nanoplatelets nanocomposite for high performance EMI shielding application

The incessant growth of technology has extensively increased the usage of electronics and telecommunication devices, leading to critical electromagnetic (EM) pollution and affecting the performance of intensely sensitive electronic devices. Herein, graphene nanoplatelets (GNP) were synthesized from the microwave intercalation method, followed by water-bath sonication. The different dosing of synthesized GNP (2, 4, 6, and 8 wt%) is further encapsulated in polyurethane (PU) matrix via solution casting technique to obtain enhanced electromagnetic interference (EMI) shielding performance. It was found that the 6 wt% of GNP (GNP6) having a density of 0.74 g/cc shows excellent stretching mechanical properties (> 400%), mechanical strength (1.4 times PU), electrical conductivity (2.75 S/m) and microwave properties. The maximum EMI shielding efficiency (SE) of 40.9 dB and 70.5 dB is noticed for GNP6 at 1 mm and 2 mm thickness, respectively. The SE is also measured for GNP6 2 mm thick sample after mechanically bending for 500 cycles and observed average variation < 3 dB. The EMI SE is measured after placing the GNP6 inside the waveguide at different bending radii varying from 3 to 9 mm, and 75 dB of SE is observed for a bending radius of 3 mm. The fabricated GNP6 nanocomposite can show stable EMI shielding performance even after immersion in pure water, followed by sonication treatment for 2 h and confirming the capability of the nanocomposite to handle the complex environment. The EMI shielding mechanism for GNP/PU is extensively explained concerning the microstructure and microwave properties. The computational analysis is done by simulating the GNP6 in the CST microwave studio tool over the broad frequency range (1-18 GHz). Thus, the highly stretchable, flexible, and lightweight GNP6 is a favourable nanocomposite providing a high EMI shielding value for next-generation electronic packaging of flexible electronic devices and coating of conformal devices used in aerospace industries.