Luminescent–Magnetic Cellulose Fibers, Modified\nwith Lanthanide-Doped Core/Shell Nanostructures

Abstract

Novel luminescent–magnetic\ncellulose microfibers were prepared\nby a dry–wet spinning method with the use of <i>N</i>-methylmorpholine-<i>N</i>-oxide. The synthesized luminescent–magnetic\ncore/shell type nanostructures, based on the lanthanide-doped fluorides\nand magnetite nanoparticles (NPs)Fe₃O₄/SiO₂/NH₂/PAA/LnF₃, were used as\nnanomodifiers of the fibers. Thanks to the successful incorporation\nof the bifunctional nanomodifiers into the cellulose structure, the\nfunctionalized fibers exhibited superior properties, that is, bright\nmulticolor emission under UV light and strong magnetic response. By\nthe use of the as-prepared fibers, the luminescent–magnetic\nthread was fabricated and used to sew and make a unique pattern in\nthe glove material, as a proof of concept for advanced, multimodal\ncloths’/materials’ protection against counterfeiting.\nThe presence and uniform distribution of the modifier NPs in the polymer\nmatrix were confirmed by X-ray diffraction, scanning electron microscopy,\nand energy-dispersive X-ray analysis (EDX). The concentration of the\nmodifier NPs in the fibers was determined by inductively coupled plasma\nmass spectrometry, EDX, and magnetic measurements. The luminescence\ncharacteristics of the materials were examined by photoluminescence\nspectroscopy, and their magnetic field-responsive behavior was investigated\nby a superconducting quantum interference device.