Double Lock Label Based on Thermosensitive Polymer Hydrogels for Information Camouflage and Multilevel Encryption

Abstract

Developing extra safety encryption technologies to prevent information leakage and combat fakes is in high demand but is challenging. Herein, we propose a "double lock" strategy based on both lower critical solution temperature (LCST) and upper critical solution temperature (UCST) polymer hydrogels for information camouflage and multilevel encryption. Two types of hydrogels were synthesized by the method of random copolymerization. The number of À COÀ NH 2 groups in the network structure of the hydrogels changed the enthalpic or entropic thermo-responsive hydrogels, and ultimately precisely controlled their phase transition temperature. The crosslink density of the polymer hydrogels governs the diffusion kinetics, resulting in a difference in the time for their color change. The combination of multiple LCST and UCST hydrogels in one label realized information encryption and dynamic information identification in the dimensions of both time and temperature. This work is highly interesting for the fields of information encryption, anti-counterfeiting, and smart responsive materials.

Droplets in soft materials

“…With increasing temperature, the material surface treated with higher ethanol concentrations will become opaque earlier, suggesting solvent‐induced reversible information recording, self‐encryption, and multidecryption. Similarly, a double lock encryption strategy is further developed using both temperature and time as keys 24 . In this example, a “double lock” strategy is executed by a combination of the poly‐( N ‐isopropylacrylamide‐acrylamide) hydrogel (L‐AM x ‐BIS y ) with LCST and poly‐( N,N ‐dimethyl(acrylamidopropyl)ammonium butanesulfonateacrylamide hydrogel (U‐AM x ‐BIS y ) with upper critical solution temperature (UCST) thermosensitive polymer hydrogels.…”

“…Similarly, a double lock encryption strategy is further developed using both temperature and time as keys. 24 In this example, a "double lock" strategy is executed by a Information encryption can also be achieved through switchable porous elastomers made from water droplet-embedded polymers. As discussed in the section on water droplet-embedded polymers, water volatilization would lead to switchable creases in PDMS.…”

“…(a) The double lock encryption QR label only can be scanned successfully in a certain period at a specific temperature. 24 Copyright 2022, Wiley-VCH. (b) Programmable forgetting process of PA gels.…”

“…Optical modulation of droplet‐embedded polymers for information encryption. (a) The double lock encryption QR label only can be scanned successfully in a certain period at a specific temperature 24 . Copyright 2022, Wiley‐VCH.…”

“…[18][19][20][21] The embedded droplets endow the materials with many appealing functions. [22][23][24] The composites containing healing agent droplets represent one of the most famous examples, which initiate the big field of self-healing materials. [25][26][27] Although the structures of droplet-embedded composites are well described in many fields, they are quite diverse and Droplet.…”