Repeatable Instantaneous Chromogenic and Magnetic-Responsive Hydrogels Based on an Agarose-Locust Bean Gum Network

Magnetism-responsive photonic crystals can achieve contactless external-field control. Thus, they have considerable potential applications in areas such as displays, sensing, and anticounterfeiting. However, overcoming the limitations of traditional liquid systems and designing solid-state magnetically responsive photonic crystals capable of repeatable and instantaneous color change in response to a magnetic field still presents significant challenges. Herein, based on agarose-locust bean gum hydrogel (AG-LBG) and superparamagnetic Fe3O4@SiO2 nanoclusters, we propose a new strategy of fabricating a repeatable, instantaneous, chromogenic, and magnetism-responsive hydrogel (AG-LBG/Fe3O4@SiO2). The special large-pore network structure of AG-LBG endows it with internal fluidity at the microscale, ensuring magnetism-responsive reordering in the solid state of Fe3O4@SiO2. Given these features, AG-LBG/Fe3O4@SiO2 had significant potential in displays and sensing. This work provided a viable strategy for the simple and inexpensive preparation of solid-state magnetism-responsive photonic crystals.