Information security has received increasing attention in daily life, and has also promoted the development of new materials and technologies for encryption, anti-counterfeiting, and information security storage. By combining multiple anti-counterfeiting technologies or utilizing multiple external stimuli (such as light, temperature, pH, and humidity) for information decryption, the encrypted information becomes difficult to interpret and replicate, thus the security of information storage can be effectively improved. However, integrating different types of anti-counterfeiting technologies into a system often requires complex assembly methods and is difficult to avoid mutual interference. Meanwhile, complex decryption operations often require expensive and cumbersome decryption devices. Therefore, it is highly challenging to achieve secure storage of information through simple encryption/decryption methods.
On the other hand, rewritable materials can reversibly write/erase information under specific stimuli such as light, solvents, ions, acids/bases, or competitive guest molecules, which has attracted great attention in the field of information storage. However, most of the currently reported rewritable materials have chemical reactivity or are based on gel systems. They are vulnerable to the influence of chemical residues/accumulation or undergo volume change with solvent evaporation, which limits the rewritability and sensitivity. Therefore, it is necessary to develop a rewritable material with fast response speed, rewritability, simple preparation, and mild conditions.
In this work, Professor Chenghui Li, in collaboration with Professor Quan Li from Southeast University, designed a series of dual responsive multi domain liquid crystal elastomers (LCEs), utilizing their transition from opaque to transparent state under strain/temperature stimulation to achieve multi-level information encryption and real-time, rewritable transient information display.
Figure 1.Dual responsive liquid crystal elastomers for multi-level information encryption
When the liquid crystal elastomer transform from multi-domain state to single-domain state under strain or from nematic phase to isotropic phase, the as-prepared multi-domain LCEs samples can achieve a reversible transition from opaque to transparent state, and the transition strain or temperature is highly dependent on the content of long chain flexible spacers. Therefore, information encrypted using different LCE inks can be decrypted at specific strains or temperatures, thereby achieving multi-level protection of information. In addition, combining the phase transition of multi domain LCEs and the photothermal effect of multi-walled carbon nanotubes (MWCNTs), near infrared light can be used as a writing pen to achieve rewritable transient information display. This work provides new options for developing multiple stimulus response materials and has potential application prospects in data storage, encryption, and display systems.
Figure 2. Dual responsive liquid crystal elastomers for transient information display
The related paper entitled “A Dual-Responsive Liquid Crystal Elastomer for Multi-Level Encryption and Transient Information Display” has been published in Angewandte Chemie International Edition (DOI: 10.1002/anie.202313728). Prof. Cheng-Hui Li and Prof. Quan Li are the corresponding author and doctoral student Hong-Qin Wang is the first author. This work was funded by National Natural Science Foundation of China (Grant No. 22271139), the Jiangsu Innovation Team Program, the Fundamental Research Funds for the Central Universities, and the Postgraduate Research & Practice Innovation Program of Jiangsu Province (KYCX23-0113).