Liquid exfoliated molybdenum disulfide (MoS₂) nanosheets and polyaniline (PANI) nanoparticles are dispersed in polystyrene (PS) matrix to fabricate hybrid polymer composites with high dielectric and electromagnetic interference (EMI) shielding behavior. A phase-separated morphology is formed when PANI and MoS₂ are incorporated into polystyrene (PS) matrix. An increasing concentration of MoS₂ nanoparticles inside PS/PANI (5 wt %) polymer blend forms an interconnected network, resulting in high electrical conductivity and dielectric behavior, making them a suitable candidate for EMI shielding application. An increment in dielectric constant and loss, up to four and five orders of magnitude, respectively, is recorded at a maximum concentration of 1 wt % of MoS₂ in PS/PANI-5 polymer blend at 100 Hz. The enhanced dielectric characteristics for PS/PANI/MoS₂ composites are then theoretically evaluated for the estimation of EMI shielding effectiveness in the frequency range of 100 Hz to 5 MHz. The maximum dielectric constant and loss achieved for PS/PANI-5 wt %/MoS₂-1 wt % are responsible for estimated shielding effectiveness of around 92 dB at 100 Hz. The increase in dielectric behavior and shielding effectiveness is probably due to the increased number of charged dipoles accumulated at the insulator–conductor interface.

Polyvinyl alcohol (PVA)-stabilized graphene nanosheets (GNS) of lateral dimension (L) ~1 μm are obtained via liquid phase exfoliation technique to prepare its composites in the PVA matrix. These composites show low levels of reinforcements due to poor alignment of GNS within the matrix as predicted by the modified Halpin-Tsai model. Drawing these composites up to 200 % strain, a significant improvement in mechanical properties is observed. Maximum values for Young’s modulus and strength are ~×4 and ~×2 higher respectively than that of neat PVA. Moreover, the rate of increase of the modulus with GNS volume fraction is up to 700 GPa, higher than the values predicted using the Halpin-Tsai theory. However, alignment along with strain-induced de-aggregation of GNS within composites accounts well for the obtained results as confirmed by X-ray diffraction (XRD) characterization.

Hybrid polymer composites based on poly vinylidene fluoride (PVDF) matrix are fabricated by dispersion of few layered graphene (FLG) and nickel spinal ferrites (NSF) for improving EMI shielding effectiveness. The FLG loading is kept constant at 3 wt% while NSF content is varied from 15–30 wt% in PVDF using solution processing technique. The shielding effectiveness in the frequency domain of 1–12 GHz is enhanced ranging 25 dB–45 dB for PVDF/FLG composite as compared to ∼0 dB for neat PVDF. With addition of NSF up to 15 wt%, the attenuation is increased to 30 dB–53 dB, clearly indicating the effective interaction and network formation of FLG and NSF in PVDF matrix. Moreover, the shielding effectiveness trend is reduced to 12 dB–43 dB as the NSF loading is increased to 30 wt% owing to its agglomeration. Absorption is the dominant phenomena in obtaining the total shielding effectiveness of ∼53 dB for PVDF/FLG-3 wt%NSF-15 wt% hybrid polymer composites. Additionally, the I-V curves provide the electrical conductivity trend while scanning electron microscope (SEM) confirms the network formation in hybrid composite.

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.