Abstracts Category : Other

Dynamical Behaviors of Coupled Self-Oscillating Gels

by Yongwoon Kim

Synchronization is the process when two interacting periodic rhythms adopt the samefrequency. This can be determined by the strength of the interactions between the rhythms inwhat is known as coupling. The type of coupling and its strength can determine the ratio offrequencies between the two interacting rhythms or oscillators, which can be a ratio ofintegers. Synchronization is widely found in nature. For instance, it can be found in neural netcommunication and in the generation of heart beats. These natural systems can be mimickedby synthetic systems. One example is self-oscillating gels, which are polymer networks with ametal catalyst covalently bonded into the polymer chain. This catalyst can participate in achemical reaction. In doing so, these gels, arranged spatially nearby one another, can have thecapability of communicating with each other through the diffusion of chemical species. Thus,these gels can synchronize their oscillations and produce different oscillating patternsdepending on the coupling strength. In groups of self-oscillating gels participating in thevBelousov-Zhabotinsky (BZ) reaction, it has been found that the gel volume, inter-gel distance,and the concentration of the metal catalyst dictate which gel acts as the pacemaker or leadinggel of an oscillatory cycle. This work seeks to understand which of these factors prevail inleading the oscillatory cycle when all factors are present simultaneously and if perturbationsusing light can cause changes in the synchronization of these gels. For this purpose, wesynthesized and prepared cubic self-oscillating BZ gels with a ruthenium (II/III) complex catalyst,and immersed them into a solution of BZ reactants. Here, four gels were arranged spatially atthe corners of a square and oscillation patterns were observed. In some experiments, theperturbation of the four gel synchronization was induced by irradiating the gels with highintensity light. Our results show that in conditions of strong coupling, the group of gelsoscillates almost simultaneously. We also found that the inter-gel distance factor prevails overthe tendency of the smallest gel to behave as the leading oscillator. In symmetricconfigurations, where volumes and inter-gel distances are equal to one another, anti-clockwiseoscillation patterns can be observed. When light is used to perturb the system, we find that itinduces a change in the frequency ratio of the oscillators and can ???reset??? oscillation patterns. Inshort, it can change the preexisting oscillation patterns.