Volume oscillation of microphase-separated gel

In this study, The volume oscillation of the microphase-separated, self-oscillating gel above the volume phase transition temperature is discussed. The self-oscillating gel is composed of N-isopropylacrylamide (NIPAAm) with a metal catalyst for the Belousov-Zhabotinsky (BZ) reaction, which is known as the oscillating reaction. The influence of temperature on the period and the self-oscillating behavior is clarified. The volume change of the gel is explained by a change of the Flory-Huggins interaction parameter, χ, which is induced by the hydration and dehydration of the polymer chain due to a valance change of the metal catalyst (Ru(bpy)₃²⁺ ↔ Ru(bpy)₃³⁺) below the volume phase-transition temperature. In contrast, the volume change of the gel is explained by a change of the Donnan osmotic pressure. The volume oscillation of a microphaseseparated gel above the volume phase transition temperature is discussed. The oscillating motion is produced by the dissipating chemical energy of the oscillating reaction, that is, the Belouzov-Zhabotinsky (BZ) reaction occuring inside the gel. Although the gel is completely composed of synthetic polymer, it shows a self-oscillation as if it is alive.