# Rare Earth Fluorescent Composite Hydrogel with Controllable Color Photoluminescence for Information Encryption

## TL;DR

A new hydrogel material with adjustable light color is developed for secure data encryption and anti-counterfeiting applications.

## Contribution

A rare earth composite hydrogel with controllable photoluminescence color and pH responsiveness is developed for information encryption.

## Key findings

- The hydrogel's photoluminescence color can be adjusted from red to green using rare earth ions.
- The material's compressive strength improved by 30.7% after rare earth ion incorporation.
- The material's luminescence intensity decreases with increasing NaOH concentration, enabling dynamic optical encryption.

## Abstract

In the context of the information age, the need for data security and confidentiality is becoming increasingly urgent. In this study, polyvinyl alcohol (PVA) and polyethylene glycol (PEG) were used as the matrix, and a PVA/PEG/rare earth composite hydrogel material with controllable photoluminescence color was successfully developed by incorporating rare earth ion doping. Through scanning electron microscopy (SEM), X-ray photoelectronic spectroscopy (XPS), X-ray diffraction (XRD), and fluorescence spectroscopy, it was confirmed that the introduction of lanthanide metal light-emitting units makes the material’s photoluminescence color adjustable from red to green, significantly improves the mechanical properties, and the compressive strength is increased from 17.6 MPa to 23 MPa, representing a 30.7% improvement. In addition, the material exhibits excellent alkaline pH response characteristics; as the concentration of NaOH solution increases, the luminous intensity gradually decays to complete quenching. Based on the adjustable light color and dynamic response characteristics, the material can realize information concealment and encryption through programmable light color changes, providing a new functional material solution for intelligent anti-counterfeiting and optical encryption.