IP: 91.222.239.160 On: Tue, 22 Sep 2020 19:04:05 Copyright: American Scientific Publishers Delivered by Ingenta Copyright © 2020 American Scientific Publishers All rights reserved Printed in the United States of America Article Journal of Nanoscience and Nanotechnology Vol. 20, 2847–2857, 2020 www.aspbs.com/jnn Co/Co 3 O 4 Based Nanoparticles and Their Polymer Composites for Tuned Electromagnetic Interference Shielding Application Madhvi Tiwari 1 , M. A. Arya 1 , Priyesh V. More 1 , Saurabh Parmar 2 , Suwarna Datar 2 , and Pawan K. Khanna 1 ∗ 1 Nanomaterials/QDs Laboratory, Department of Applied Chemistry, Defence Institute of Advanced Technology, Defence Research and Development Organisation, Pune 25, India 2 Department of Applied Physics, Defence Institute of Advanced Technology, Pune 25, India The magnetic properties of the metal nanoparticles (NPs) can play remarkable role in electromag- netic interference shielding (EMI Shielding) of many defence and commercial electronic devices. In the present work, coconut oil and PVA capped magnetic cobalt/cobalt oxide nanoparticles (Co/Co 3 O 4 NPs) were synthesized by chemical reduction method and impregnated in polymer matrix to verify their EMI shielding behaviour. The coconut oil capped Co/Co 3 O 4 NPs with presence of hcp and fcc phases were prepared in the size domain of 7–10 nm and the effect of surfactant (the oil) on size and oxidation state was studied by varying the ratios. The shielding efficiencies of Co/Co 3 O 4 NPs PVA nanocomposites were analysed by using vector network analyser (VNA) in X- and K u -band ranging from 8 GHz–18 GHz. The VNA results showed increased shielding efficiency with increasing concentration of NPs. Keywords: Nanoparticles, Coconut Oil, Magnetism, EMI Shielding. 1. INTRODUCTION Nanotechnology is an emerging field that covers an exten- sive range of disciplines, including the frontiers of chem- istry, materials, electronics, medicine, information storage, sensors, communication, energy conversion and storage, environmental protection, aerospace etc. [1–2]. Nanoma- terials design, synthesis, characterization are the basis of nanotechnology and tailored particles are expected to open new avenues to several emerging technological appli- cations [1–4]. Nanomaterials exhibit superior chemical, optical, electronic, magnetic, mechanical, and biological properties that are often significantly different from their corresponding micron sized counterparts. These improved or novel properties depend on the composition, surface funtionalization, atomic structure, size confinement effect, microstructure, interfaces and defects, all of which can be tailored by chemical synthesis and other treatment [4–6]. The nanomaterials may be crystalline, semi-crystalline or close to amorphous particles of inorganic or organic nature. Due to presence of effective surface capping the ∗ Author to whom correspondence should be addressed. particles can be dispersed in desired solvents, homoge- nized in dense liquids or a polymeric or inorganic matrix. They can be converted to colloids, aggregates, emulsions or suspensions, thin or thick films etc. Metal nano parti- cles e.g., Ag, Au, Pd, Pt, Fe, Ni, Co, and many bimetal- lic particles and/or alloys are finding increasing advanced technological applications in today’s scientifically driven society. The present work has been focused on Cobalt nanoparticles with spherical or non-spherical morphology exhibit remarkable magnetic, catalytic and antibacterial properties compare to bulk cobalt metal due to high sur- face area/energy, reactivity, lower melting point, super- magnetic behaviour, higher thermal conductivity etc. There are a variety of commercial and defence appli- cations of cobalt nanoparticles cobalt nano-particles e.g., as sensor [7], as contrast agent for Magnetic Resonance Imaging (MRI), drug delivery agent and many other med- ical tools, as catalyst for Fisher-Tropsch synthesis, and some other technological applications like data storage, as a magnetic fluids etc. [8]. Cobalt nanoparticles can be synthesized by various chemical methods and their morphology and size can be J. Nanosci. Nanotechnol. 2020, Vol. 20, No. 5 1533-4880/2020/20/2847/011 doi:10.1166/jnn.2020.17474 2847