Self-Oscillating Gel(concentration to mechanic oscillations) A novel polymeric gel was reported[R. Yoshida and T. Takahashi, JACS 118, 5134 (1996)] which autonomously swells and deswells periodically in a closed homogeneous solution without any external stimuli, similar to autonomic phenomena in life such as heartbeat. The mechanical oscillation is achieved by inducing the Belousov-Zhabotinsky (BZ) reaction within the gel. A copolymer gel of N-isopropylacrylamide (IPAAm) in which ruthenium(II) tris-(2,2'-bipyridine) (Ru(bpy)32+), a catalyst for the BZ reaction, is covalently bonded to the polymer chain. The poly(IPAAmco-Ru(bpy)3) gel swells and deswells at the oxidized and reduced states of Ru(bpy)3, respectively. The BZ reaction in the gel generates periodic redox changes of Ru(bpy)3, and the chemical oscillation induces mechanical oscillation of the polymer utilize a gel in which the BZ reaction causes periodic redox changes within the polymer network. 在BZ反应中，Ru(bpy)3在2+和3+氧化态间周期变化。当配合物由 2+氧化至3+，因荷电聚合物链变得更加亲水，聚合物的水合性增强，改变相转变温度。而相 转变温度决定IPAAm基聚合物是否溶胀或收缩。因此随着氧化状态交替变化，凝胶甚至在温度 保持恒定时也能周期性溶胀(在氧化态)及收缩(于还原态)。此类化学反应震荡引起凝胶体积 振荡，类似于消化道和蚯蚓的蠕动。 Coming soon, more of this topic ... |