Our group has been investigating autonomously oscillating hydrogel microspheres (microgels), which spontaneously convert the chemical energy into swelling/deswelling oscillatory motion. The oscillations of the microgels were synchronized with the Belousov-Zhabotinsky (BZ) reaction, where immobilized Ru(bpy)3 acted as a catalyst and the redox states of Ru(bpy)3 were periodically changed. For example, the oscillating microgels are useful in, e.g., rheology modifiers, micropumps without an external device energy source, high-performance catalytic carriers. Thus, individual microgel design is important for their collective-motion control. Microgels are soft and deformable particles composed of cross-linked three-dimensional networks swollen by water. Due to their open structures, chemical substrates can diffuse into the interior or exterior of the microgels. In this study, we have newly designed the component microgels that control the BZ reaction, which is the driving source of the oscillating motion, by adjusting the diffusion of the substrate into the gel (Figure). Moreover, the microgel assemblly made it possible to control macroscopic behavior. This achievement would be useful for the development of advanced bioinspired materials.

Motion control of the hydrogel microspheres driven by chemical oscillation reaction

ACS Spring 2022

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