Turing-like spatial patterns in a polyacrylamide-methylene blue-sulfide-oxygen system

Watzl, M; Münster, Arno F.

doi:10.1016/0009-2614(95)00743-n

Cited by 39 publications

(32 citation statements)

References 14 publications

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“…[7][8][9] Here, we show that patterns similar but not identical to TS arise during the polymerization of acrylamide in the presence of sulfide alone.…”

Section: Introductionmentioning

confidence: 57%

Pattern Formation during Polymerization of Acrylamide in the Presence of Sulfide Ions

1998

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When polyacrylamide gel is prepared from a mixture of acrylamide, N,N′-methylene-bisacrylamide and triethanolamine with a peroxodisulfate initiator in the presence of sulfide, spatial pattern formation occurs in the gel if water is spread on top of the gel after it solidifies. These patterns, typically arrays of spots or stripes, persist for many hours. Analysis of the effects of temperature, composition, stirring, and other factors suggests that the pattern formation occurs during polymerization due to convection driven by the highly exothermic polymerization reaction. The role of sulfide ion, which is essential for the pattern formation, appears to be to terminate the polymer chain elongation while maintaining the overall exothermic chain reaction.

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“…[7][8][9] Here, we show that patterns similar but not identical to TS arise during the polymerization of acrylamide in the presence of sulfide alone.…”

Section: Introductionmentioning

confidence: 57%

Pattern Formation during Polymerization of Acrylamide in the Presence of Sulfide Ions

1998

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“…In these conditions, a wealth of standing and traveling patterns that were undocumented in this reaction could be produced. In this quest, one must still beware of convection that is always lurking as stressed by the ongoing debate around the patterns observed in the methylene blue-sulfide-oxygen system [Watzl & Münster, 1995;Kurin-Csörgei et al, 1998Münster, 1999;Orbán et al, 1999]. In this and other cases, further effects may have to include the coming into play of the mechanical changes that occur in the material supporting the reaction (e.g.…”

Section: Discussionmentioning

confidence: 99%

Diffusive Instabilities and Chemical Reactions

Borckmans

Dewel

Wit

et al. 2002

Int. J. Bifurcation Chaos

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Diffusive instabilities provide the engine for an ever increasing number of dissipative structures. In this class autocatalytic chemical systems are prone to generate temporal and spatial self-organization phenomena. The development of open spatial reactors and the subsequent discovery in 1989 of the stationary reaction-diffusion patterns predicted by Turing [1952] have triggered a large amount of research. This review aims at a comparison between theoretical predictions and experimental results obtained with various type of reactors in use. The differences arising from the use of reactions exhibiting either bistability of homogeneous steady states or a single one in a CSTR are emphasized.

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“…This dimer is most likely the species observed in thin gel sheets of the PA-MBO system by Watzl and Münster. 1 We want to reemphasize that the results presented in this Article are obtained from experiments that showed no signs of precipitation.…”

Section: Methodsmentioning

confidence: 99%

“…Following the preparation of Watzl and Münster, we used the complete PA-MBO system and recrystallized sulfide. 1 However, NaOH was added to further increase the pH of the system and the polymerized gel was covered neither by water nor by a methylene solution. Additional experiments revealed no qualitative changes if the gel was covered with a thin layer of water.…”

Section: Methodsmentioning

confidence: 99%

“…1,2 The question whether these patterns arise from convection phenomena during the gelation of the system or from a Turing-like chemical instability [3][4][5][6] is under discussion in the current literature. [7][8][9] Several findings support the hypothesis of a Turinglike instability: (a) experiments reveal that the response of the patterns to externally applied electric fields and light perturbations is in agreement with numerical results obtained from reaction-diffusion calculations; 2,10 (b) qualitative experimental results indicate that the patterns form several minutes after gelation; 1 (c) as shown in numerical simulations, the reaction mechanism of the MBO system has a structure that is capable of supporting Turing patterns.…”

Section: Introductionmentioning

confidence: 99%

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Complex Pattern Formation in the Polyacrylamide−Methylene Blue−Oxygen Reaction

1999

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The polyacrylamide-methylene blue-oxygen system reveals a variety of complex concentration patterns. Chevron and white-eye patterns develop from simple hexagons in a slow, continuous transition process. A third type of structure (honeycombs) forms from either white-eye patterns or hexagons. This transition occurs rapidly along propagating fronts. Two-dimensional Fourier analyses reveal that the complex patterns have a simple structure and that the wave vectors of the initial hexagons are conserved in all transitions. Quantitative data on surface undulations of the gel are presented. The surface structure resembles the structure of the observed methylene blue patterns. A schematic phase diagram is presented that characterizes the pattern geometry in terms of reaction time and initial sulfide concentration.

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Turing-like spatial patterns in a polyacrylamide-methylene blue-sulfide-oxygen system

Cited by 39 publications

References 14 publications

Pattern Formation during Polymerization of Acrylamide in the Presence of Sulfide Ions

Pattern Formation during Polymerization of Acrylamide in the Presence of Sulfide Ions

Diffusive Instabilities and Chemical Reactions

Complex Pattern Formation in the Polyacrylamide−Methylene Blue−Oxygen Reaction

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