It remains challenging to enable the optical switching for safety-improvedinformation encryption/decryption on a gel platform. Herein, a waterswelling-induced optical-switching strategy is reported that can achievemultistage information encryption/decryption on an organohydrogel surface.Cationic moieties of methacrylamido propyl trimethyl ammonium chloride(MPTAC) and hydrophobic fluorophores of (2-(4-vinylphenyl) ethene-1,1,2-triyl) tribenzene (TPE) are copolymerized into hydrophilic polyacrylamidenetwork. The cationic moieties are capable of increasing the water swellingability of the network, and the fluorophores endow the network with weakblue fluorescence. Upon low swelling with water (swelling ratio in weight <50), hydrophobic fluorophores of TPE aggregate to enhance the fluorescenceunder ultraviolet light. This process is accompanied with the phase transitionof organohydrogel into a non-transparent state. After being saturatedwith water, the fluorescence disappears and the organohydrogel returns tothe transparent state. Such water swelling-induced optical switching can beused for multistage information encryption/decryption with improved safety.Various information patterns are created on the surface of organohydrogel bylaser cutting to demonstrate the complex information encryption/decryptionprocesses. This strategy not only provides a meaningful inspiration for informationencryption/decryption but also enables an optical-switching platformfor potential anti-counterfeiting and displaying.
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