Sulfhydryl-functionalized anisotropic photonic crystal hydrogels for visual Hg2+ detection and adsorption in cinnabar mine water area

Inspired by the ultrastructure of cephalopod skin, we used dodecyl glyceryl itaconate and polyacrylamide to self – assemble an anisotropic photonic crystal hydrogel, PDGI/PAAm-SH. The hydrogel, which is functionalized with sulfhydryl groups, follows the hard-soft acid-base (HSAB) principle and demonstrates a strong affinity for Hg 2+ . After undergoing two activation steps, PDGI/PAAm-SH displays a red structural color and harbors numerous binding sites . When Hg 2+ chelates with the hydrogel, it triggers volume contraction, leading to a blue-shift in the reflection peak. Notably, this hydrogel exhibits an impressive adsorption capacity of 129.06 mmol·kg −1 . Its unique structure enables real-time and highly sensitive monitoring of color alterations during the adsorption process . Moreover, the hydrogel showcases excellent mechanical properties and remarkable mechanochromic behavior. Being stable, portable, and reusable, PDGI/PAAm-SH holds great promise for water sample detection applications. Emissions of mercury ions from human activities during mining and smelting processes cannot be overlooked due to their potential for environmental pollution. Consequently, developing a material that offers both visual detection capability and efficient adsorption for Hg 2+ is crucial. Inspired by cephalopod skin, we have prepared a sulfhydryl-functionalized anisotropic photonic crystal hydrogel (PDGI/PAAm-SH). The bilayer structure of polydodecyl glyceryl itaconate (PDGI) is immobilized and stabilized within the sulfhydryl-functionalized polyacrylamide network after polymerization. The porous structure of hydrogel facilitates the adsorption of Hg 2+ in solution, resulting in a blue shift in structural color, which allows for visual detection. The PDGI/PAAm-SH effectively adsorbs and removes Hg 2+ from water, with an impressive uptake capacity of 129.06 mmol kg −1 . Additionally, this hydrogel exhibits good reproducibility, excellent mechanical properties, and remarkable selectivity for Hg 2+ . It can shield interference from other ions during detection and shows promising applications in environmental monitoring and purification.