2D nanosheets and composites for EMI shielding analysis

Liquid exfoliated, 2-dimensional (2D), few layered graphene and molybdenum disulfide nanosheets (GNS and MNS) are size selected for EMI shielding application. Scanning electron microscopy (SEM) has confirmed the lateral dimensions increase (1-2 µm for GNS and MNS) with lowering centrifugation speed (1000 to 500 rpm). The micron size (~ 15 µm) restacked structures of GNS and MNS (L ~ 2 µm) over a nylon membrane have shown ~ 16 dB and ~ 6 dB EMI shielding effectiveness (1-8 GHz frequency), respectively. The enhanced EMI shielding effectiveness for GNS-500 may be credited to its high carrier mobility as well as high aspect ratio of nanosheets. The GNS-500 are further dispersed (0.3 wt.%) in thermoplastic polyurethane for their applicability as flexible EMI shielding material. The dielectric characteristics predicted an enhancement for the attenuation (200 MHz-1 GHz). The experimental results (1-8 GHz) suggested the maximum attenuation ~ 18 dB showing the composite applicability as a broadband EMI shielding material.