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arXiv 2401.04043cond-mat.soft
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由化学相互作用介导的活性胶体的自组织

Self-organization of active colloids mediated by chemical interactions

Zhiwei Peng, Raymond Kapral

AI总结:

该研究探究多化学物种反应网络与多胶体物种参与反应的体系中活性胶体的自组织,对比不同反应类型的胶体体系行为,发现引入化学反应网络参数可拓展胶体自组织设计空间,产生丰富非平衡结构。

摘要:

自驱动胶体粒子展现出丰富的非平衡现象,在药物递送、自组装活性材料等领域具有广阔的应用前景。此前的实验与理论研究表明,消耗或产生某种化学物质的化学活性胶体,可依据有效泳动相互作用自组织形成具备多样特征的团簇。本文研究了包含多种发生反应网络的化学物质、以及参与不同反应的多种胶体的系统中的自组织现象。由具有潜在非线性动力学的复杂化学反应驱动的活性胶体,可利用酶包覆颗粒表面发生的酶促反应来实现。为阐明自组织行为如何取决于活性胶体催化的化学反应及其所处的化学环境,我们首先研究了发生简单催化反应的单种胶体体系,并将这一被广泛研究的案例与发生序列反应的胶体二元混合物、以及发生非线性自催化反应的胶体二元混合物的自组织行为进行对比。我们的结果表明,总体而言,在存在本体化学反应和泳动吸引力的情况下,低粒子密度的活性胶体可形成局域团簇。但团簇的特征取决于本体和粒子表面的反应动力学,以及泳动系数。当仅存在一种或两种仅发生表面反应的化学物质时,可能的自组织形式的空间十分有限。通过引入涉及胶体表面和流体中反应的化学反应网络所带来的额外系统参数,胶体自组织的设计空间可以得到拓展,进而产生多种多样的非平衡结构。

英文摘要:

Self-propelled colloidal particles exhibit rich non-equilibrium phenomena and have promising applications in fields such as drug delivery and self-assembled active materials. Previous experimental and theoretical studies have shown that chemically active colloids that consume or produce a chemical can self-organize into clusters with diverse characteristics depending on the effective phoretic interactions. In this paper, we investigate self-organization in systems with multiple chemical species that undergo a network of reactions and multiple colloidal species that participate in different reactions. Active colloids propelled by complex chemical reactions with potentially nonlinear kinetics can be realized using enzymatic reactions that occur on the surface of enzyme-coated particles. To demonstrate how the self-organizing behavior depends on the chemical reactions active colloids catalyze and their chemical environment, we consider first a single type of colloid undergoing a simple catalytic reaction, and compare this often-studied case with self-organization in binary mixtures of colloids with sequential reactions, and binary mixtures with nonlinear autocatalytic reactions. Our results show that in general active colloids at low particle densities can form localized clusters in the presence of bulk chemical reactions and phoretic attractions. The characteristics of the clusters, however, depend on the reaction kinetics in the bulk and on the particles and phoretic coefficients. With one or two chemical species that only undergo surface reactions, the space for possible self-organizations are limited. By considering the additional system parameters that enter the chemical reaction network involving reactions on the colloids and in the fluid, the design space of colloidal self-organization can be enlarged, leading to a variety of non-equilibrium structures.

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