Influence of Initial Substrate Concentration of the Belouzov-Zhabotinsky Reaction on Transmittance Self-Oscillation for a Nonthermoresponsive Polymer Chain

Abstract

We succeeded in causing transmittance self-oscillations of a novel self-oscillating polymer chain induced by the Belouzov-Zhabotinsky (BZ) reaction under constant conditions. The novel polymer chain was composed of a biocompatible and non-thermoresponsive poly-vinylpyrrolidone (PVP) main-chain, covalently-bonded to the ruthenium catalyst (Ru(bpy) 3 ) of the BZ reaction. We investigated the influence of initial substrate concentrations of the three BZ substrates on the transmittance self-oscillation of the novel polymer solution. As a result, we demonstrated that the width of the transmittance self-oscillation is significantly affected by these initial concentrations. However, the amplitude of the transmittance self-oscillation is hardly affected by the BZ substrate conditions. Furthermore, the period of the self-oscillation has a good linear relationship to the concentration of the BZ substrates. Therefore, the period of the self-oscillation can be controlled by the selection of the initial concentrations of the BZ substrates.

Autonomous Oscillation of Nonthermoresponsive Polymers and Gels Induced by the Belousov–Zhabotinsky Reaction

“…Thus, we can control the self-oscillating behavior by selecting an appropriate molecular structure of the polymer main chain. Figure 7 shows that all the logarithmic plots of the period of the self-oscillation of the VP-based polymer as a function of the initial molar concentration of one BZ substrate chain show good linear relationships [49]. Therefore, the period [T(s)] of the self-oscillation can be expressed as a [substrate] b where a and b are experimental constants and brackets denote the initial concentration.…”

“…It was demonstrated that there was no LCST for the VP-based polymer chain in the reduced and oxidized states (see Figure 4) [49]. The solubility of the VP-based polymer chains was different in the reduced and oxidized states, as evidenced by the different transmittance values.…”

“…This difference can be attributed to the chemical structure of the VP main chain. As shown in Figure 5, the VP-based polymer chain undergoes transmittance self-oscillation originating from the aggregation-disaggregation of the polymer chain induced by the BZ reaction, since the amount of polymer aggregation is larger in the oxidized state than in the reduced state, which leads to changes in transmittance due to changes in the light scattering from the aggregated polymers [49]. As shown in Figure 5, the baseline of the self-oscillation gradually decreases with time under all measurement conditions because of the sudden increase in the ionic strength of the solution when the measurements start [39,40].…”

“…In previous reports, Hara et al described various types of self-oscillating polymer systems with nonthermoresponsive main chains. Among them, we selected poly-vinylpyrrolidone (PVP) [48][49][50][51][52] and poly(2-propenamide) (polyacrylamide) (PAM) [53][54][55] for discussion here. As for the VP-based self-oscillating polymer chain, the influence of the concentrations of the three BZ substrates (sodium bromate, malonic acid, and nitric acid; not including metal catalyst) on the waveform and period of the self-oscillation was investigated.…”

Influence of the Belousov–Zhabotinsky substrate concentration on the lifetime and self-oscillating behavior of a polymer solution

“…The polymer chain is driven while consuming malonic acid, the energy source of the BZ reaction. This occurs because self-oscillating behavior is induced by a BZ reaction originating from the Ru(bpy)3 moiety in the polymer chain [13][14][15][16][17][18][19][20][21][22]. The BZ reaction has been much investigated and is a well-known oscillating reaction that causes spontaneous redox oscillation and a wide variety of nonlinear phenomena.…”