Direct observation of periodic swelling and collapse of polymer chain induced by the Belousov-Zhabotinsky reaction.

By utilizing a quartz crystal microbalance with dissipation (QCM-D), we directly observed the self-oscillating behavior of a polymer chain induced by the Belousov-Zhabotinsky (BZ) reaction. We succeeded in measuring self-oscillations of the resonance frequency (Δf) and dissipation (ΔD), which originate in the self-oscillating behavior of the polymer chain on a gold surface induced by the BZ reaction. We synthesized a self-oscillating polymer chain with Ru as the catalyst of the BZ reaction and a chemical adsorption site, so as to directly observe its periodic swelling and collapse on the gold surface. Distinct self-oscillation of ΔD synchronized with the self-oscillation Δf was observed. The period of the Δf self-oscillation was about 400 s, and the induction time was about 6.5 h. In QCM-D measurements, we found that the peaks of Δf and ΔD oscillations did not coincide in time because the state of the Gaussian chain did not coincide with the maximum value of Δf. Moreover, examination of the relationship between Δf and ΔD revealed that their oscillatory waveforms were identical in frequency but differed in phase and amplitude.