Browsing by Author "Morsali, Mohammad"

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Open Access
Chemical tracking of temperature by concurrent periodic precipitation pattern formation in polyacrylamide gels
(American Chemical Society, 2022-01-20) Khan, Muhammad Turab Ali; Kwiczak-Yiğitbaşı, Joanna; Tootoonchian, Pedram; Morsali, Mohammad; Lagzi, Istvan; Baytekin, Bilge
In nature, nonequilibrium systems reflect environmental changes, and these changes are often “recorded” in their solid body as they develop. Periodic precipitation patterns, aka Liesegang patterns (LPs), are visual sums of complex events in nonequilibrium reaction–diffusion processes. Here we aim to achieve an artificial system that “records” the temperature changes in the environment with the concurrent LP formation. We first illustrate the differences in 1-D LPs developing at different temperatures in terms of band spacings, which can demonstrate the time, ramp steepness, and extent of a temperature change. These results are discussed and augmented by a mathematical model. Using scanning electron microscopy, we show that the average size of the CuCrO4 precipitate also reflects the temperature changes. Finally, we show that these changes can also be “recorded” in the 2-D and 3-D LPs, which can have applications in long-term temperature tracking and complex soft material design.
Open Access
Mechanical control of periodic precipitation in stretchable gels to retrieve information on slastic deformation and for the complex patterning of matter
(Wiley-VCH Verlag, 2020-03) Morsali, Mohammad; Khan, Muhammad Turab Ali; Ashirov, Rahym; Holló, G.; Baytekin, H. Tarık; Lagzi, I.; Baytekin, Bilge
Material design using nonequilibrium systems provides straightforward access to complexity levels that are possible through dynamic processes. Pattern formation through nonequilibrium processes and reaction–diffusion can be used to achieve this goal. Liesegang patterns (LPs) are a kind of periodic precipitation patterns formed through reaction–diffusion. So far, it has been shown that the periodic band structure of LPs and the geometry of the pattern can be controlled by experimental conditions and external fields (e.g., electrical or magnetic). However, there are no examples of these systems being used to retrieve information about the changes in the environment as they form, and there are no studies making use of these patterns for complex material preparation. This work shows the formation of LPs by a diffusion–precipitation reaction in a stretchable hydrogel and the control of the obtained patterns by the unprecedented and uncommon method of mechanical input. Additionally, how to use this protocol and how deviations from “LP behavior” of the patterns can be used to “write and store” information about the time, duration, extent, and direction of gel deformation are presented. Finally, an example of using complex patterning to deposit polypyrrole by using precipitation patterns is shown as a template.
Open Access
Mechanically controlled liesegang pattern formation in stretchable polyacrylamide gels for elastic deformation tracking
(2019-07) Morsali, Mohammad
Pattern formation in nature has been intellectually appealing for many scientists since antiquity. Simultaneous diffusion and reaction of chemicals in gel media may lead to precipitation and complex pattern formation through self-assembly. Periodic precipitations patterns, also known as Liesegang patterns (LP), are one of the stimulating examples of such self-assembling reaction-diffusion systems. So far, it was shown that LP’s periodic band structure and their unique geometry can be controlled by controlling the reaction parameters (e.g. concentration of the reactants) and affecting the reaction medium (e.g. external electrical field). However, so far, the research on LPs have been concentrated mostly around how these patterns are forming, to retrieve information to build a universal mathematical model for them. Although there are studies showing the effect of external fields on the development of these patterns, to the best of our knowledge, so far, there is no example of these systems, used to retrieve information about the changes in the environment as they form. Here, we first show the formation of Liesegang rings by a diffusion-precipitation reaction in a stretchable hydrogel. Then, we present how to use these patterns to ‘read’ the duration, the extent, and the direction of gel deformation. Also, we describe deviations from LP behavior for the patterns (spacing that can be mathematically defined by a geometrical series) formed after the unloading. We believe this first display of such an ‘environmental sensing’ to be a starting point for more investigations on many aesthetically appealing and mathematically challenging self-assembled systems, which have been studied for decades.