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.