NSF-DFG Confine: MolPEC -- Molecular theory of weak polyelectrolytes in confined space

NSF-DFG Confine：MolPEC——有限空间中弱聚电解质的分子理论

• 批准号: 509155421
• 负责人: Professor Dr. Marcus Müller
• 金额: --
• 依托单位: Department of Chemical and Environmental Engineering
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/509155421?language=en
• 关键词: NSF; DFG; Confine; MolPEC; Molecular

Building on complementary advances in polymer density functional theory (PDFT) and molecular simulation, the US-German team will study the structure, thermodynamics, and dynamics of weak polyelectrolytes at and between surfaces. The idea is to combine and extend Ising Density Functional Theory (iDFT) and Single-Chain-in-Mean-Field (SCMF) simulation. iDFT considers single-chain configurations and ionization states of segments on equal footing and captures liquid-like packing and electrostatic correlations via the molecular density, ρ(X). This joint probability distribution of configurations and ionization states of an entire macromolecule is dictated by a single-chain potential, ω(X), which, in turn, is a functional of the molecular density. The high-dimensional molecular density will be efficiently evaluated via SCMF simulation on parallel, GPU-accelerated supercomputers, employing the iDFT single-chain potential. We will extend the simulation code, SOft coarse grained Monte-carlo Acceleration (SOMA), to incorporate electrostatic interactions and nonlocal interactions along the molecular contour. The particle-based simulation, Dynamic-iDFT (D-iDFT), accounts for long-range fluctuations and allows us to study the configuration dynamics. Additionally, we will derive a segment-based dynamic iDFT (SD-iDFT) for describing the local polymer mass and charge density in response to environmental changes.The combined computational scheme will be applied to four prototypical, scientific questions: (i) SCMF/iDFT simulations will study the adsorption of weak polyelectrolytes onto surfaces, focusing on the coupling between single-chain configurations, ionization states, and polymer-surface interactions. (ii) Additionally, iDFT will investigate surface free energies and polymer-induced interactions between surfaces, and study the role of segment sequences and surface heterogeneities. (iii) Subsequently, we will study the coacervation of polycations and polyanions in confined aqueous solution, focusing on the interplay between wetting and phase behavior in thin films and geometric confinement. (iv) Moreover, we will use D-iDFT simulations and SD-iDFT to study the collective dynamics of confined, weak polyelectrolytes in response to changes of environmental conditions, such as pH or salt concentration. These molecular simulations are able to predict the temporal evolution of segment and charge density profiles from the underlying dynamics of polymer ionization and single-chain configurations. In all cases we will study model systems to validate our computations by comparison between SCMF simulation, iDFT, and literature data, and subsequently extend our studies to more complex systems, accounting for different segment sequences and chemistry of the confinement. These theoretical and computational advances will contribute to a rational design of weak polyelectrolyte systems for a wide spectrum of technological applications.

基于聚合物密度泛函理论（PDFT）和分子模拟的互补进展，美国-德国团队将研究弱聚电解质在表面和表面之间的结构，热力学和动力学。其思想是联合收割机和扩展伊辛密度泛函理论（iDFT）和单链平均场（SCMF）模拟。iDFT在同等基础上考虑单链构型和链段的电离状态，并通过分子密度ρ（X）捕获类液体堆积和静电相关性。整个大分子的构型和电离态的联合概率分布由单链势ω（X）决定，而单链势ω（X）又是分子密度的函数。高维分子密度将有效地评估通过SCMF模拟并行，GPU加速的超级计算机，采用iDFT单链势。我们将扩展的模拟代码，软粗粒蒙特-卡罗加速（索马），将静电相互作用和非局部相互作用沿着分子轮廓。基于粒子的模拟，动态iDFT（D-iDFT），解释了长程波动，并使我们能够研究配置动力学。此外，我们将推导出一个基于片段的动态iDFT（SD-iDFT），用于描述局部聚合物质量和电荷密度对环境变化的响应。组合计算方案将应用于四个原型科学问题：（i）SCMF/iDFT模拟将研究弱聚电解质在表面上的吸附，重点是单链构型、电离态、和聚合物-表面相互作用。(ii)此外，iDFT将调查表面自由能和表面之间的聚合物诱导的相互作用，并研究链段序列和表面异质性的作用。(iii)随后，我们将研究聚阳离子和聚阴离子在受限水溶液中的凝聚，重点是薄膜中的润湿和相行为以及几何约束之间的相互作用。(iv)此外，我们将使用D-iDFT模拟和SD-iDFT来研究受限的弱聚电解质响应于环境条件（如pH值或盐浓度）变化的集体动力学。这些分子模拟是能够预测的时间演变的片段和电荷密度分布从聚合物电离和单链配置的基本动力学。在所有情况下，我们将研究模型系统，通过SCMF模拟，iDFT和文献数据之间的比较来验证我们的计算，随后将我们的研究扩展到更复杂的系统，考虑不同的片段序列和化学约束。这些理论和计算的进步将有助于为广泛的技术应用合理设计弱耦合系统。