A novel fluorophore–spacer–receptor to conjugate MWNTs and ferrite nanoparticles to design an ultra-thin shield to screen electromagnetic radiation

Abstract

A novel fluorophore–spacer–receptor has been designed with hydrazono methyl phenol as the receptor, anthracene as the fluorophore and imine (CN) groups as the spacer. This newly designed fluorophoric system has a receptor that can bind with ferrites and a fluorophore core that can conjugate non-covalently with multiwalled carbon nanotubes (MWNTs) via π–π conjugation. The hybrid nanoparticles were thoroughly characterized using Raman, UV-vis and fluorescence spectroscopy. This unique hybrid is further explored as a novel material to screen electromagnetic (EM) radiation. By precisely localizing these hybrids in a given phase of an immiscible co-continuous blend, unique microstructures can be constructed. Herein, blends of polyvinylidene fluoride (PVDF) and polycarbonate (PC) were chosen as a model system. The hybrid nanoparticles were selectively localized in the PVDF phase owing to its higher polarity and were systematically characterized by electron microscopic and solution–dissolution techniques. The hybrid nanoparticles that were designed to shield from the incident EM radiation resulted in >99.99% attenuation, dominated mostly by absorption. This non-covalent approach of conjugating MWNTs with ferrites, aided by the fluorophoric system, was noted to be a more effective way to improve the properties (both bulk electrical conductivity and structural) than direct physical mixing/covalent conjugation approaches. In order to further enhance the shielding effectiveness (SE), a layer-by-layer architecture was constructed essentially with outer layers containing PC/PVDF blends with a MWNT–ferrite hybrid and the inner layers consisting of PC/PVDF blends with only MWNTs. An ultra-thin shield of 0.90 mm showed >99.9999% attenuation suggesting new pathways for designing lightweight, flexible EMI shielding materials.