Department of Chemistry and Biochemistry, Florida State University, Tallahassee, FL 32306-4390.
Proc Natl Acad Sci U S A. 2023 Jul 11;120(28):e2305172120. doi: 10.1073/pnas.2305172120. Epub 2023 Jul 3.
Chemical gardens are complex, often macroscopic, structures formed by precipitation reactions. Their thin walls compartmentalize the system and adjust in size and shape if the volume of the interior reactant solution is increased by osmosis or active injection. Spatial confinement to a thin layer is known to result in various patterns including self-extending filaments and flower-like patterns organized around a continuous, expanding front. Here, we describe a cellular automaton model for this type of self-organization, in which each lattice site is occupied by one of the two reactants or the precipitate. Reactant injection causes the random replacement of precipitate and generates an expanding near-circular precipitate front. If this process includes an age bias favoring the replacement of fresh precipitate, thin-walled filaments arise and grow-like in the experiments-at the leading tip. In addition, the inclusion of a buoyancy effect allows the model to capture various branched and unbranched chemical garden shapes in two and three dimensions. Our results provide a model of chemical garden structures and highlight the importance of temporal changes in the self-healing membrane material.
化学花园是由沉淀反应形成的复杂的、通常是宏观的结构。它们的薄壁将系统分隔开来，如果内部反应物溶液的体积因渗透或主动注入而增加，它们的大小和形状会进行调整。众所周知，空间限制在薄层中会导致各种模式，包括自延伸丝状结构和围绕连续扩展前缘组织的花状图案。在这里，我们描述了一种用于这种自组织类型的元胞自动机模型，其中每个晶格位置被两种反应物或沉淀物之一占据。反应物注入会导致沉淀物的随机替换，并产生一个扩展的近圆形沉淀物前缘。如果这个过程包括一个有利于替换新鲜沉淀物的年龄偏差，那么在实验中就会出现薄壁丝状结构，并在前沿处像生长一样扩展。此外，包含浮力效应可以使模型在二维和三维空间中捕获各种分支和非分支的化学花园形状。我们的结果提供了一种化学花园结构的模型，并强调了自修复膜材料中时间变化的重要性。
