Aspects of the Belousov–Zhabotinsky Reaction inside a Self-Oscillating Polymer Brush

Abstract

We have developed a novel polymer brush surface exhibiting autonomous swelling-deswelling changes driven by the Belousov-Zhabotinsky (BZ) reaction, that is, the self-oscillating polymer brush. In this system, the ruthenium tris(2,2'-bipyridine) [Ru(bpy)] catalyst-conjugated polymer chains are densely packed on the solid substrate. It is expected that the BZ reaction in the polymer brush would be influenced by the immobilization effect of the catalyst. To clarify the effect of the immobilization of the catalyst on the self-oscillating polymer brush, the self-oscillating behavior of the polymer brush was investigated by comparing it with that of other self-oscillating polymer materials, the free polymer, and the gel particle under various initial substrate concentrations. The initial substrate dependency of the oscillating period for the polymer brush was found to be different from those for the free polymer and the gel particle. Furthermore, the oscillatory waveform was analyzed on the basis of the Field-Körös-Noyes model. These investigations revealed that the dense immobilization of the self-oscillating polymer on the surface restricted accessibility for the Ru(bpy) moiety. These findings would be helpful in understanding the reaction-diffusion mechanism in the polymer brush, which is a novel reaction medium for the BZ reaction.

Oscillating Reactions Meet Polymers at Interfaces

“…That the mobility of polymer chains could affect the oscillating behavior of self-oscillating polymer brushes was envisioned already in the previously discussed 2015 [ 86 ] and 2016 [ 87 ] studies, but a dedicated study on the effect of metal catalyst confinement inside the crowded environment of a polymer brush appeared only in 2018. In this work, Masuda et al [ 92 ] compared the self-oscillating behavior of poly(NIPAAm- co -NAPMAm- co -[Ru(bpy) 3 ]NAPMAm) in the form of free chains, gel particles and surface-attached brushes ( Figure 9 ), confirming that in polymer brushes peculiar reaction-diffusion patterns can arise due to chain crowding and reduced accessibility of metal catalyst.…”

“…That the mobility of polymer chains could affect the oscillating behavior of self-oscillating polymer brushes was envisioned already in the previously discussed 2015 [86] and 2016 [87] studies, but a dedicated study on the effect of metal catalyst confinement inside the crowded environment of a polymer brush appeared only in 2018. In this work, Masuda et al [92] compared the self-oscillating behavior of poly(NIPAAm-co-NAPMAm-co-[Ru(bpy) 3 ]NAPMAm) in the form of free chains, gel particles and surface-attached brushes (Figure 9), confirming that in polymer brushes peculiar reaction-diffusion patterns can arise due to chain crowding and reduced accessibility of metal catalyst. That the mobility of polymer chains could affect the oscillating behavior of self-oscillating polymer brushes was envisioned already in the previously discussed 2015 [86] and 2016 [87] studies, but a dedicated study on the effect of metal catalyst confinement inside the crowded environment of a polymer brush appeared only in 2018.…”

“…The scale bar is 50 s in all plots. Adapted and reproduced with permission from [ 92 ]. American Chemical Society, 2018.…”

Stimuli‐Responsive Ruthenium‐Containing Polymers

“…On the basis of this principle, various RCPs have been developed by copolymerization with other functional monomers, including AMPS, MAPTAC, NAS, VP, AA, and spirobenzopyran monomers and other self‐oscillating phenomena, including viscosity oscillation, turbidity oscillation, and fluorescence oscillation of RCP brushes have also been realized.…”

Self‐Oscillating 3D Printed Hydrogel Shapes

“…This active electron movement results in spatiotemporal patterns that provide a platform to study and understand nature. [ 3 ]…”