# A Facile Eutectic Strategy for Scalable, Leakage‐Free Thermochromic Phase‐Change Composites Enabling Smart Temperature Labels and Secure Data Encryption

## TL;DR

A new method creates stable, leak-proof materials that change color with temperature, useful for smart labels and data encryption.

## Contribution

A scalable eutectic strategy using lauric acid and sodium acetate trihydrate to produce leakage-free thermochromic composites.

## Key findings

- The SAT/LA eutectic shows enhanced intermolecular interactions preventing leakage and phase separation.
- Thermochromic composites demonstrate cyclically reversible color change and high latent heat capacity.
- Applications in smart temperature labels and secure data encryption are successfully demonstrated.

## Abstract

Solid–liquid phase change materials (PCMs), when used as solvents in organic thermochromic composite systems, often suffer from leakage issues, which degrade their reversible color‐changing capability. Although encapsulation and porous composite shape‐stabilization techniques can enhance the structural integrity of PCMs, these methods are often complex, limited to lab‐scale production, and costly. Hereby, a facile eutectic strategy is presented to develop leakage‐free PCMs for stabilizing organic thermochromic composites by integrating organic lauric acid (LA) and inorganic sodium acetate trihydrate (SAT). Molecular dynamics simulations reveal significantly enhanced intermolecular interactions between SAT and LA compared to those between LA molecules. These strengthened intermolecular interactions endow the SAT/LA eutectic with excellent shape stability, preventing leakage and phase separation. Benefiting from the superior properties of the SAT/LA eutectic, the resulting thermochromic composites exhibit outstanding shape stability, cyclically reversible thermochromic performance, and considerable latent heat capacity. Leveraging these advantages, applications in temperature indicators, thermally regulated quick response codes, information encryption, and data storage/disguise are successfully demonstrated. This work, guided by molecular dynamics simulations, offers a promising approach to designing industrial‐scale, cost‐effective, shape‐stabilized thermochromic materials for temperature indication and information encryption.

A facile eutectic strategy is developed, guided by molecular dynamics simulations, to create leakage‐free phase change materials from lauric acid and sodium acetate trihydrate. These organic–inorganic eutectic composites effectively stabilize thermochromic dyes, yielding materials with exceptional shape stability and cyclically reversible color change. This enables advanced applications in smart labels, information encryption, and thermal data storage.