Preparation of a Transparent Photoluminescent Self-Healable Smart Ink for a Dual-Mode Security Authentication

Abstract

Ultraviolet-induced photochromism has been an attractive dual-mode security encoding approach to enhance the anticounterfeiting performance of commercial products. However, photochromic inks have recently reported major drawbacks, including high cost, low efficacy, and poor durability. Herein, we report the development of self-healing security ink using poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS) immobilized with rare-earth-activated aluminate nanoparticles for advanced anticounterfeiting applications. Remarkably, self-healable security inks can ensure durability and photostability. The self-healing composite ink demonstrated ultraviolet-induced photochromism with high reversibility and photostability. Various self-healing composite inks of diverse emission properties were developed using various concentrations of rare-earth-activated aluminate nanoparticles. Homogeneous films were printed onto paper sheets, demonstrating a colorless appearance that changed to green under ultraviolet rays as proved by the CIE Lab. The morphological properties of the phosphor were examined, demonstrating a particle diameter of 4-9 nm. Various analytical methods were used to investigate the morphology and chemical composition of the prepared photochromic films. Both the rheological and mechanical properties of the ink solution and the ink-printed paper sheets were measured. The luminescent films had an excitation wavelength of 365 nm (colorless) and an emission peak at 520 nm (green). Various industries can benefit greatly from the current smart ink as an efficient strategy for the development of anticounterfeiting commercial products.