Modeling autonomously oscillating chemo-responsive gels

Polymer gels undergoing the Belousov–Zhabotinsky (BZ) reaction are unique materials because the polymer network can undergo autonomous oscillations in the absence of external stimuli. We describe theoretical and computational approaches that allow us to simulate these BZ gels and highlight our recent findings that reveal the rich dynamical behavior exhibited by these distinctive materials. In particular, we found that the nature of the oscillatory behavior is highly dependent on the size of the sample. Thus, by tailoring the sample's size, we can design gels that exhibit a uniform swelling and deswelling or display more complicated shape changes, which involve complex chemo-mechanical traveling waves. We then discuss a remarkable form of mechano-chemical transduction in these gels, where the application of an external force can drive a non-oscillatory system to exhibit sustained oscillations, and autonomous rotational motion. Due to this sensitivity to mechanical deformation, the BZ gels could potentially be used as a smart, responsive coating, which transmits a global signal to indicate that the system has been impacted. Finally, we focus on heterogeneous gels, which encompass regular arrangements of BZ patches within a non-reactive polymer matrix. By varying the placement of these BZ patches within the matrix, we could modify the functionality of the material or introduce multi-functional behavior within a single sample. Overall, the examples indicate that our methodology provides a powerful technique for probing the properties of such soft active materials.