Mechanical Control of Periodic Precipitation in Stretchable Gels to Retrieve Information on Elastic Deformation and for the Complex Patterning of Matter

• Published in: Advanced materials (Weinheim) Vol. 32; no. 10; pp. e1905779 - n/a
• Main Authors: Morsali, Mohammad, Khan, Muhammad Turab Ali, Ashirov, Rahym, Holló, Gábor, Baytekin, H. Tarik, Lagzi, Istvan, Baytekin, Bilge
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.03.2020
• Subjects: Chemical precipitation; Complexity; Diffusion; Elastic deformation; Hydrogels; Information retrieval; Liesegang phenomena; nonequilibrium systems; Patterning; periodic patterns; polyacrylamide gel; Polypyrroles; reaction–diffusion; stretchable gels; nonequilibrium systems; Liesegang phenomena; reaction-diffusion; polyacrylamide gel; stretchable gels; periodic patterns
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201905779

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. Just like life rings record the effect of changes in weather on a growing tree, concurrently developing precipitation patterns can sense and record the mechanical input on a hydrogel. This action can be used to track the time, duration, and direction of elastic mechanical deformation. The developed patterns can also be used as templates in complex patterning of secondary materials.