Hydrogels with UCST behavior and UV/temperature-induced multicolor fluorescence for synergistic coding and encryption

Abstract

The development of hydrogels capable of emitting multicolor fluorescence presents a promising avenue for addressing concerns related to information leakage and distortion of sensitive data. The integration of multifactor-induced tunable fluorescence with a unique upper critical solution temperature (UCST) behavior in hydrogels significantly contributes to the development of multi-dimensional and multi-level information storage materials that can dynamically display information as well as offer a high level of security and protection for information. However, the fusion of these advantageous properties into hydrogels intended for information storage and display remains a considerable challenge. In this context, we introduce a novel three-dimensional (3D) fluorescent code-producing hydrogel array fabricated via vat photopolymerization (VP) 3D printing, a technique offers a sustainable and efficient approach. This array unites the desired properties, capable of sequentially revealing concealed information through two distinct steps: (i) a heat-induced phase transition, and (ii) multicolor fluorescence triggered by ultraviolet (UV)/temperature exposure under specific conditions (i.e., certain UV irradiation duration, heating time, and wavelength). The reversible transparency and reprogrammable fluorescence emission properties of these hydrogels are expected to significantly enhance the processes of information encryption and anti-counterfeiting. This advancement could potentially revolutionize the field of information security.