title: Engineering Nanostructures by Decorating Magnetic Nanoparticles onto Graphene Oxide Sheets to Shield Electromagnetic Radiations.
abstract: In this study, a minimum reflection loss of -70 dB was achieved for a 6 mm thick shield (at 17.1 GHz frequency) employing a unique approach. This was accomplished by engineering nanostructures through decoration of magnetic nanoparticles (nickel, Ni) onto graphene oxide (GO) sheets. Enhanced electromagnetic (EM) shielding was derived by selectively localizing the nanoscopic particles in a specific phase of polyethylene (PE)/poly(ethylene oxide) (PEO) blends. By introduction of a conducting inclusion (like multiwall carbon nanotubes, MWNTs) together with the engineered nanostructures (nickel-decorated GO, GO-Ni), the shielding efficiency can be enhanced significantly in contrast to physically mixing the particles in the blends. For instance, the composites showed a shielding efficiency >25 dB for a combination of MWNTs (3 wt %) and Ni nanoparticles (52 wt %) in PE/PEO blends. However, similar shielding effectiveness could be achieved for a combination of MWNTs (3 wt %) and 10 vol % of GO-Ni where in the effective concentration of Ni was only 19 wt %. The GO-Ni sheets facilitated in an efficient charge transfer as manifested from high electrical conductivity in the blends besides enhancing the permeability in the blends. It is envisioned that GO is simultaneously reduced in the process of synthesizing GO-Ni, and this facilitated in efficient charge transfer between the neighboring CNTs. More interestingly, the blends with MWNTs/GO-Ni attenuated the incoming EM radiation mostly by absorption. This study opens new avenues in designing polyolefin-based lightweight shielding materials by engineering nanostructures for numerous applications.
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Prasanna Kumar S
authors.initials: PK
authors.lastname: Mural
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Shital Patangrao
authors.initials: SP
authors.lastname: Pawar
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Swetha
authors.initials: S
authors.lastname: Jayanthi
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Giridhar
authors.initials: G
authors.lastname: Madras
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Ajay K
authors.initials: AK
authors.lastname: Sood
authors.affiliation: †Center for Nano Science and Engineering, ‡Department of Materials Engineering, §Department of Chemical Engineering, and ∥Department of Physics, Indian Institute of Science, Bangalore-560012, India.
authors.forename: Suryasarathi
authors.initials: S
authors.lastname: Bose
keywords: EMI shielding; MWNT; PE/PEO blends; graphene oxide; nickel nanoparticles