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Multiscale and stochastic simulations of nanostructured interfaces in aqueous systems.

机译:水性系统中纳米结构界面的多尺度随机模拟。

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Recently, interfacial nanostructures have attracted considerable interest due to different applications in materials science, catalysis, nanotechnology, and biotechnology. Robust and accurate simulation tools can help broaden the capability to synthesize, control, and manipulate nanostructured materials. In this study, mesoscopic and self-consistent multiscale simulations have been developed to investigate the relationship between the macroscopic process variables and morphological evolution of interfacial nanostructures.; This dissertation is broadly divided into two parts. In the first part, Brownian dynamics simulation (BDS) is used to investigate the influence of interfacial reaction rate on the morphology of interfacial nanostructures synthesized by electrodepositon. It is shown that the size dispersion of metallic nanoparticles growing on randomly distributed nucleation sites can be reduced by lowering the interfacial reaction rate. For nanostructured coatings on fibers, a morphological transition from dense to open coatings is obtained as the process changes from reaction controlled to diffusion controlled. A thorough quantitative description of the morphological evolution of the coating and a comparison with lattice-based mesoscopic simulation for asymptotic scaling laws are presented for the first time.; In the second part, a concurrent multiscale simulation for colloidal deposition is developed by self consistently coupling BDS with continuum-level conservation equations. The technique is validated for non-interacting particles, and shown to be computationally efficient as compared to brute-force BDS. The simulation technique is extended to colloidal deposition in the presence of particle interactions. For the first time, simulations of irreversible colloidal deposition are shown to predict kinetics and structure consistent with experiments without the use of adjustable parameters. Subsequently the effects of particle desorption and surface diffusion on colloidal deposition are examined. For the first time, consistent with experimental observations, the simulations demonstrate that asymptotic coverage of small particles exhibits non-monotonic trends, while those of large particles increase monotonically with increasing ionic strength. For large particles, surface diffusion is shown to induce ordered structures, and the critical ionic strength required for disorder-order transition decreases with decreasing particle size. Finally, the influence of dipole interactions on the structure and surface pressure of colloidal monolayers at fluid-fluid interfaces is studied.
机译:近来,由于在材料科学,催化,纳米技术和生物技术中的不同应用,界面纳米结构引起了相当大的兴趣。强大而准确的仿真工具可以帮助扩展合成,控制和操纵纳米结构材料的能力。在这项研究中,介观和自洽的多尺度模拟已经被开发来研究宏观过程变量和界面纳米结构形态演变之间的关系。本文大致分为两个部分。在第一部分中,使用布朗动力学模拟(BDS)研究了界面反应速率对电沉积合成的界面纳米结构形态的影响。结果表明,通过降低界面反应速率,可以减小在随机分布的成核位点上生长的金属纳米粒子的尺寸分散。对于纤维上的纳米结构涂层,随着过程从反应控制到扩散控制的变化,获得了从致密涂层到开放涂层的形态转变。首次对涂层的形态演变进行了全面的定量描述,并与基于晶格的介观模拟进行了渐近缩放定律的比较。在第二部分中,通过将BDS与连续谱级守恒方程自洽耦合,开发了并发的胶体沉积多尺度模拟。该技术已针对非相互作用粒子进行了验证,并且与蛮力BDS相比在计算上非常有效。在存在粒子相互作用的情况下,模拟技术扩展到了胶体沉积。首次显示不可逆胶体沉积的模拟可预测动力学和结构,与实验相符,而无需使用可调参数。随后检查了颗粒解吸和表面扩散对胶体沉积的影响。与实验观察一致,该模拟首次证明小颗粒的渐近覆盖率呈现非单调趋势,而大颗粒的渐近覆盖率则随着离子强度的增加而单调增加。对于大颗粒,表面扩散显示出诱导有序结构,无序过渡所需的临界离子强度随粒径的减小而降低。最后,研究了偶极子相互作用对流体-流体界面处胶体单层结构和表面压力的影响。

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