Switching the BZ reaction with a strong-acid-free gel.

In the present study, a novel gel with a semi-interpenetrating polymer network (semi-IPN) that undergo the Belousov-Zhabotinsky (BZ) reaction without the addition of a strong acid (HNO3 or H2SO4) was developed. The required concentrations of the BZ substrates, sodium bromate (NaBrO3) and malonic acid (MA), under these conditions were higher than under the normal BZ reaction conditions, involving the addition of a strong acid. The period of the BZ reaction with the novel gel (semi-IPN BZ gel) decreased with increasing concentrations of NaBrO3 and MA. Moreover, the connection of the semi-IPN BZ gel to a conventional BZ gel facilitated the reaction in the latter through the propagation of the intermediates from the former to the latter. The BZ reaction stopped when the conventional BZ gel was disconnected from the semi-IPN BZ gel. These results demonstrate that the BZ reaction in the conventional BZ gel underwent on-off switching, controlled by its attachment to the semi-IPN BZ gel. This on-off switching mechanism would be valuable in controlling actuators and robots without strong acids.