Macroporous Photonic Hydrogels for Encryption of Structural-Color Patterns
발표자
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초록
내용
Colloidal crystals exhibit structural colors that are tunable by an external stimulus. Thus, the colloidal crystals have been used for stimuli-responsive colorimetric sensors. In this study, we design macroporous hydrogels that are highly reversible switching between transparent dried state and structurally-colored wet state. The macroporous hydrogels are prepared by film-casting of photocurable dispersions of silica particles and selectively removing silica particles. The cavities of hydrogels are randomly collapsed due to the capillary force, being transparent in a dried state. The regular array of cavities is restored by absorbing water-ethanol mixture, exhibiting structural colors in a wet state. The structural colors depend on the concentration of the water-ethanol mixture. The hydrogels can be micropatterned that have encrypted graphics in a dried state, which disclose hidden patterns in a wet state. Therefore, the hydrogels can be used for alcohol sensors and security materials.