Damping Behavior of the Aggregation-Disaggregation Self-Oscillation of a Polymer Chain

The effect of the initial concentration of the substrates of the Belousov-Zhabotinsky (BZ) reaction, and the temperature, on the autonomous aggregation-disaggreagtion self-oscillation of a polymer chain is investigated. The polymer chain consists of N-isopropylacrylamide (NIPAAm), a Ru catalyst of the BZ reaction, and acrylamide-2-methylpropanesulfonic acid (AMPS) as a pH and solubility control site. It is demonstrated that the initial concentration of the BZ substrates and the temperature exert an influence on the waveform and the period of the self-oscillation. Moreover, the aggregation-disaggregation self-oscillation of the polymer chain undergoes damping, that is, the amplitude of the transmittance self-oscillation decreases with time, This phenomenon is attributed to an increase in the size of the polymer aggregates during the self-oscillating behavior. Therefore, the damping behavior is significantly affected by the initial concentration of the BZ substrates in accordance with the Field-Koros-Noyes (FKN) mechanism. In addition, it is shown that the self-oscillating region is determined by the initial concentrations of the BZ substrates and the temperature. This study clarifies that the self-oscillation of the AMPS-containing polymer chain can be controlled by the selection of the initial concentration of the BZ substrates and the temperature under acid-free conditions.