Synthesis of Eu1-xGdx(TTA)3 Phen Complexes and Preparation of Water-based Fluorescent Anti-counterfeiting Ink

Abstract

The ever-changing and rampant counterfeit goods have promoted the development of security anti-counterfeiting technology. The functional anti-counterfeiting inks, especially the fluorescent inks have obtained much more attention from researchers due to the characteristics of convenient detection, excellent security performances, and favorable stability. In this study, a solution method involving two ligands (-thenoyltrifluoroacetone (HTTA) and Phenanthroline (Phen)) and two rare earth elements (Eu and Gd) was proposed to prepare Eu1-xGdx(TTA)3Phen complexes (where x is the molar fraction of doping elements). The compounds were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), photoluminescence spectroscopic (PL) and thermogravimetric analysis (TGA). The obtained Eu1-xGdx(TTA)3Phen was then incorporated into waterborne polyurethane to prepare fluorescent inks. The results showed that the synthetic Eu1-xGdx(TTA)3Phen complexes presented excellent performances, such as good dispersion, strong fluorescence intensity, and high thermal stability. The crosslinking density of waterborne polyurethane exhibited a significant influence on the luminescent properties. The ink and printing products were invisible under ambient conditions, while showed bright red fluorescence under ultraviolet (UV) light, which indicated that the ink possesses a good anti-counterfeiting performance and was promising to be widely used as a packaging material.