Dependence of turbidity oscillations of self-oscillating polymers on the selective recognition of the crown ether receptors contained in the polymer chain.

The turbidity oscillations of self-oscillating polymers in the Belousov-Zhabotinsky (BZ) reaction system depending on the crown ether receptors contained in the polymer network have been studied. The three monomers are copolymerized, namely, N-isopropylacrylamide, the metal catalyst monomer for the BZ reaction, and the crown ether receptor monomer, to prepare the self-oscillating polymers used in this study. The turbidity oscillations are characterized by monitoring the transmittance of the polymer solution in the BZ reaction system at a specific wavelength of 570 nm. The oscillations are varied by crown ether receptors used in the polymerization process, i.e., BCAm(6) or BCAm(5), for the selective recognition of specific cations between potassium and sodium ions in the solution. The selective recognition of the BCAm receptors in the polymer chain for the two ions has brought out a variation in the turbidity oscillations by a change in the hydrophilicity of the polymer chain. The oscillations of the polymer solution composed of the BCAm(5) receptor are more influenced by sodium ion, while the polymer solution of BCAm(6) receptor is affected by potassium ion. However, the oscillation patterns of the redox changes obtained by these solution systems look much alike despite the differences in the polymer chain by crown ether receptors and cations of bromate used for the BZ reaction.