A Dual‐Responsive Liquid Crystal Elastomer for Multi‐Level Encryption and Transient Information Display

Abstract

Information security has gained increasing attention in the past decade, leading to the development of advanced materials for anti‐counterfeiting, encryption and instantaneous information display. However, it remains challenging to achieve high information security with simple encryption procedures and low‐energy stimuli. Herein, a series of strain/temperature‐responsive liquid crystal elastomers (LCEs) are developed to achieve dual‐modal, multi‐level information encryption and real‐time, rewritable transient information display. The as‐prepared polydomain LCEs can change from an opaque state to a transparent state under strain or temperature stimuli, with the transition strains or temperatures highly dependent on the concentration of long‐chain flexible spacers. Information encrypted by different LCE inks can be decrypted under specific strains or temperatures, leading to multi‐level protection of information security. Furthermore, with the combination of the phase transition of polydomain LCEs and the photothermal effect of multi‐walled carbon nanotubes (MWCNTs), we achieved a repeatable transient information display by using near‐infrared (NIR) light as a pen for writing. This study provides new insight into the development of advanced encryption materials with versatility and high security for broad applications.

Dual‐Mode Hydrogels with Structural and Fluorescent Colors toward Multistage Secure Information Encryption

“…Fabrication of Dual-Mode pDGI/p(AAm-DMA-6APA-Ln 3+ ) Hydrogel: According to the previous work, the optimal coordination ratio of fluorescent monomer 6APA and lanthanide metal ions is 2:1. [50][51][52][53][54] Therefore, it was chosen to immerse pDGI/p(AAm-DMA-6APA) hydrogel with an excess concentration of Ln(NO 3 ) 3 solution to realize the effect of complete coordination. Specifically, the dual-mode pDGI/p(AAm-DMA-6APA-Ln 3+ ) hydrogel was obtained by immersing pDGI/p(AAm-DMA-6APA) hydrogel in Eu(NO 3 ) 3 or Tb(NO 3 ) 3 (0.1 M) solution for 15 min at room temperature.…”

“…Consequently, there is a crucial demand for developing anti-counterfeiting technologies that combine multiple optical information modes within a single material to overcome these limitations. [52,53] Dual or multi-optical mode materials represent a significant leap forward, offering increased information storage, enhanced anti-counterfeiting measures, and higher levels of encryption security. As a proof of concept for multistage information encryption based on dual-mode hydrogels, a random alphabet was designed, as depicted in Figure 4A.…”

Light-Induced Nontethered Rolling of Liquid Crystal Elastomer and Carbon Nanotube Composite Ring

“…These microscale changes result in large reversible actuation strain in LCE at the macroscopic level. The behavior of LCE-based smart structures has generated extensive and growing interest in fields such as soft robotics, , wearable devices, − smart display, , and bionic systems. − For example, a self-walking four legs soft robot made of LCE can walk and grasp driven by circuit-controlled Joule heating . LCE and helical metal wire composite fibers can simultaneously achieve large shape morphing, high bearing capacity, and deformation sensing monitor functions .…”

Dual-Mode Patterns Enabled by Photofluidization of an Azobenzene-Containing Linear Liquid Crystal Copolymer

“…Liquid crystal polymers (LCPs) are a class of ideal patterned polymer materials for constructing structural color patterns and chromatic polarization patterns, which possess the processability of polymers and the molecular anisotropy of liquid crystals. − On the one hand, the flowable precursors or prepolymers of LCPs provide the ability to be fabricated into precise micro/nanostructures by various methods, such as replica molding, colloidal lithography, and imprinting. , Subsequently, the micro/nanostructures are fixed by cross-linking occurring on the surface of LCPs films, enabling the creation of vibrant structural colors and intricate patterns. Yu et al utilized the characteristic of azobenzene polymers to carry athermal transitions between different mechanical states under alternate lighting conditions, by which a multinanopattern was imprinted on flexible substrates using a mask template.…”