添加盐对单价金属离子和模型水溶性聚合物界面动力学的影响
Effect of Added Salts on the Interfacial Dynamics of Monovalent Metal Ions and Model Water-Soluble Polymers
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中文总结 AI 辅助
本研究通过分子动力学模拟揭示单价盐对水溶性聚合物界面水合层动力学的影响，发现纳米尺度动态水合层迁移率梯度遵循通用函数形式，为理解离子特异性效应提供重要进展。
中文摘要 AI 辅助
电解质和聚电解质溶液的传统理论忽视了离子和聚合物的水合作用，导致对这些溶液热力学和动力学性质的认识过于理想化。特别是，某些离子在低溶液浓度下增加或降低水扩散系数的倾向，目前尚不明确，这一现象与描述盐对合成和生物大分子以及胶体颗粒溶解性和自组装影响的霍夫迈斯特序列密切相关。这些离子特异性效应在生物、医学科学和技术应用的众多领域具有深远影响。我们通过分子动力学（MD）模拟，以代表性水溶性聚合物聚丙烯酰胺（PAM）和聚环氧乙烷（PEO）在水性盐溶液中的行为，来解决理解离子和未带电水溶性聚合物水合作用的一般性问题。我们特别关注模型再现添加单价盐对水扩散系数观测趋势的能力。在基于物理真实水模型的先前MD模拟中，再现这些水迁移率的离子特异性趋势一直是一个反复出现的挑战。我们在盐溶液方面的工作代表了一项重要进展，在此基础上我们构建了添加盐的水性聚合物溶液的建模。对我们模型聚合物的模拟揭示了一个扩展的纳米尺度动态水合层，其尺度约为1纳米（nm），在该层中迁移率偏离其体相值，且该层内的迁移率梯度似乎遵循近乎通用的函数形式。
英文摘要
Traditional theories of electrolyte and polyelectrolyte solutions overlook ion and polymer hydration, yielding an overly idealized perspective of the thermodynamic and dynamic properties of these solutions. In particular, the propensity of certain ions to increase or decrease the water diffusion coefficient at low solution concentrations, is poorly understood, a phenomenon that correlates strongly with the Hofmeister series describing the influence of salts on the solubility and self-assembly of synthetic and biomacromolecules as well as colloidal particles. These ion-specific effects have profound ramifications in diverse biological, medical science and technological applications. We address the general problem of understanding ion and uncharged water-soluble polymer hydration through molecular dynamics (MD) simulations of representative water-soluble polymers, polyacrylamide (PAM) and polyethylene oxide (PEO), in aqueous salt solutions. Careful attention is given to the capacity of our model to reproduce observed trends of added monovalent salts on the diffusion coefficient of water. Reproducing these ion-specific trends in the mobility of water has been a recurrent challenge in prior MD simulations of aqueous solutions based on a physically realistic model of water. Our work on salt solutions represents an important advance on which we build our modeling of aqueous polymer solutions with added salts. Simulations of our model polymers reveal an extended nanoscale dynamic hydration layer having a scale on the order of one nanometer (nm) in which the mobility is perturbed from its bulk value, and the mobility gradient in this layer appears to obey a near universal functional form.
发表机构
- National Institute of Standards and Technology（美国国家标准与技术研究院）
- Wesleyan University（卫斯理安大学）
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