Dynamical profiles of the reactive components in direct and revert Liesegang patterns

Kalash, Leen; Farah, Hiba; Eddin, Amal Zein; Sultan, Rabih

doi:10.1016/j.cplett.2013.10.035

Cited by 13 publications

(16 citation statements)

References 22 publications

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“…This is a very rarely observed revert periodic precipitation as the usual trend is an increase of the distance between the two consecutive bands in the band number. 41 Revert periodic precipitation occurs when the excess of invading ions (diffusing from outside, e.g., silver ions) can be also efficiently adsorbed on the surface of the formed particles (e.g., silver halides) forming a charged double layer, thus electrostatically stabilizing them and preventing further aggregation to form a precipitate. 42−44 Farther from the liquid−gel interface, the excess of the stabilizing compound decreases due to the diffusive nature of the front involving a decrease of the stabilization capacity, thus facilitating the coagulation.…”

Section: Resultsmentioning

confidence: 99%

Reaction–Diffusion Assisted Synthesis of Gold Nanoparticles: Route from the Spherical Nano-Sized Particles to Micrometer-Sized Plates

et al. 2021

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The design of nanoparticles of desired sizes and shapes and 2D nanostructured materials is challenging and important due to their unique physical and chemical properties. One of the most common methods for the generation of metal nanoparticles is the wet synthetic route in which metal ions are reduced and the formed particles are stabilized in the liquid phase. Here we show a facile and powerful method to synthesize gold nanoparticles in a solid agarose gel utilizing the diffusion of reagents using the Turkevich method at room temperature. Our technique yields particles spatially separated by their sizes and shapes (spheres and plates) in the gel column. We have achieved 4 orders of magnitude difference in the sizes of the synthesized particles with a linearly increasing trend in the function of their spatial position. We have also generated micrometer-sized nanoplates with triangle, truncated triangle, or hexagon shapes attaining almost the length-to thickness ratio of 500, representing the magnificent power of the reaction–diffusion assisted synthesis.

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Section: Resultsmentioning

confidence: 99%

Reaction–Diffusion Assisted Synthesis of Gold Nanoparticles: Route from the Spherical Nano-Sized Particles to Micrometer-Sized Plates

et al. 2021

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“…Revert (or invert)-type Liesegang patterns have been infrequently mentioned and discussed in the literature because these patterns form under a limited set of conditions, unlike regular Liesegang patterns. In the revert patterns, the distance between two consecutive bands decreases, in contrast to the regular Liesegang phenomenon where it increases (Figure a). , Several systems have been identified in which revert-type pattern formation has been observed and include mercury sulfide (HgS), copper sulfide (CuS), silver chromate (Ag 2 CrO 4 ), silver iodide (AgI), and lead chromate (PbCrO 4 ) − systems. It was observed in the PbCrO 4 system that the pattern changed from revert to regular when the outer and inner electrolytes were exchanged …”

Section: Other Precipitation Structuresmentioning

confidence: 99%

Pattern Formation in Precipitation Reactions: The Liesegang Phenomenon

2019

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Pattern formation is a frequent phenomenon in physics, chemistry, biology, and materials science. Bottom-up pattern formation usually occurs in the interaction of the transport phenomena of chemical species with their chemical reaction. The oldest pattern formation is the Liesegang phenomenon (or periodic precipitation), which was discovered and described in 1896 by Raphael Edward Liesegang, who was a German chemist and photographer who was born 150 years ago. The purpose of this feature article is to provide a comprehensive overview of this type of pattern formation. Liesegang banding occurs because of the coupling of the diffusion process of the reagents with their chemical reactions in solid hydrogels. We will discuss several phenomena observed and discovered in the past century, including reverse patterns, precipitation patterns with dissolution (due to complex formation), helicoidal patterns, and precipitation waves. Additionally, we will review all existing models of the Liesegang phenomenon including pre- and postnucleation scenarios. Finally, we will highlight several applications of periodic precipitation.

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“… 10 , 11 There are various studies describing some trends and emergence of new shapes, e.g., helical patterns, at different temperatures. 12 , 13 , 22 , 14 − 21 However, these studies were mostly conducted with agarose and gelatin gels that melt above 45 and 30 °C, respectively. 19 Therefore in the LP-forming systems, the temperature is usually chosen as room temperature.…”

Section: Introductionmentioning

confidence: 99%

Chemical Tracking of Temperature by Concurrent Periodic Precipitation Pattern Formation in Polyacrylamide Gels

Khan

Kwiczak‐Yiğitbaşı

Tootoonchian

et al. 2022

ACS Appl. Mater. Interfaces

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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 CuCrO 4 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.

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Dynamical profiles of the reactive components in direct and revert Liesegang patterns

Cited by 13 publications

References 22 publications

Reaction–Diffusion Assisted Synthesis of Gold Nanoparticles: Route from the Spherical Nano-Sized Particles to Micrometer-Sized Plates

Reaction–Diffusion Assisted Synthesis of Gold Nanoparticles: Route from the Spherical Nano-Sized Particles to Micrometer-Sized Plates

Pattern Formation in Precipitation Reactions: The Liesegang Phenomenon

Chemical Tracking of Temperature by Concurrent Periodic Precipitation Pattern Formation in Polyacrylamide Gels

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