No 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.

Covalent organic frameworks (COFs) are crystalline porous polymers with designable structures and properties. Their crystallization typically relies on trial-and-error involving harsh conditions including organic solvents, presenting significant obstacles for rational design and large-scale production. Here, we present a liquid crystal directed synthesis methodology and its implementation for up to gram-scale production of highly crystalline COFs in water and air. It is compatible to monomers with different structures, shape, size, length of side chains, and electron-donating, electron-accepting and heterocyclic substitutions near reactive sites. 17 types of donor-acceptor two-dimensional COFs including 4 types of new ones and a three-Page 1 of 24 https://mc03.manuscriptcentral.com/ccsc CCS Chemistry dimensional COF with a yield of up to 94% were demonstrated, showing great generality of the method. The as-synthesized donor-acceptor COFs are organic semiconductors and contain macropores besides intrinsic mesopores which make them as attractive catalysts. The production of H 2 O 2 under visible light in water was studied and the structure-property relationships were revealed. The production rate reached 4347 μmol h -1 g cat -1 , which is about 467% better than that of the benchmark photocatalyst g-C 3 N 4 . This study will inspire the mild synthesis and scale-up of a wide spectrum of COFs and organic semiconductors as efficient catalysts, promote their structure-property investigation, and boost their applications.

Z. (2023). Growth of single-crystal imine-linked covalent organic frameworks using amphiphilic amino-acid derivatives in water. Nature Chemistry.

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