Kinetics and Thermodynamics of the Self-Assembly of Polyhedral Nano-Colloids into Pure and Mixed Crystals

多面体纳米胶体自组装成纯晶体和混合晶体的动力学和热力学

• 批准号: 1403118
• 负责人: Fernando Escobedo
• 金额: $ 28.38万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2018-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1403118&HistoricalAwards=false
• 关键词: Kinetics; Thermodynamics; Self; Assembly; Polyhedral

PI: Escobedo, Fernando A.Proposal Number: 1403118Institution: Cornell UniversityTitle: Kinetics and Thermodynamics of the Self-Assembly of Polyhedral Nano-Colloids into Pure and Mixed CrystalsPolyhedral nanoparticles (NPs) can be assembled into super-lattice materials that has the potential to form phases exhibiting vastly different optical, electronic, physical, and chemical properties. This proposal, building on past successes, will focus on understanding the kinetics of the transitions between phases, mesophases, and crystals. Such kinetics play a crucial role in the experimental realization of these structures and the insights gained would allow ways to catalyze the self-assembly process, or design ways to steer the systems into desirable phases. In the long term, such results could have an impact on the ceramic, plastics, and semiconductor industries by helping broaden the approaches available to develop stable nanocomposites, liquid armors, colloid-based mesocrystals for photonic materials, and nanocrystal arrays for photovoltaics.Advanced Monte Carlo (e.g., Gibbs-Duhem integration with semi-grand canonical ensembles) and Molecular Dynamics simulations will be used to study how hard (or square-well attraction) shapes organize at different volume fractions. For such systems, it's easy to become kinetically trapped experimentally (either as a desired or undesired structure), so it's very important to understand, not just the equilibrium state, but the kinetics, which is the focus here. In this context, the mesophases that are formed may provide intermediate states that lower the otherwise high energy barrier between disordered and crystalline states. The investigations will include not just pure systems (containing one type of polyhedral particles), but also the thermodynamics and kinetics of phase transitions in binary mixtures. Particles to be investigated include polyhedra that can be produced in experiments (cubes, cuboctahedra, truncated octahedra, and octahedra), and mixtures of those (including also spherical particles). The simulations will model the thermodynamic behavior of the mixtures, and new order parameters and variants of the forward flux sampling method will be used to simulate the kinetics of phase transitions.

PI：Escobedo，费尔南多·A。这一提议以过去的成功为基础，将集中在理解阶段，中间相和晶体之间过渡的动力学上。这种动力学在这些结构的实验实现中起着至关重要的作用，而获得的见解将允许催化自组装过程或设计将系统转向理想阶段的方法。从长远来看，这种结果可能会通过帮助扩大可用于开发稳定的纳米复合材料，液体装甲，基于胶体的光子材料中的基于胶体的中晶的方法来影响陶瓷，塑料和半导体行业，以及纳米晶体的纳米晶体阵列。分子动力学模拟将用于研究在不同体积分数以硬化（或方孔吸引）形状组织的方式。对于这样的系统，很容易在实验上被动力捕获（无论是所需的结构还是不希望的结构），因此，不仅是平衡状态，而且是动力学，这是这里的重点非常重要。在这种情况下，形成的中间相可能会提供中间状态，这些状态降低了无序状态和晶体状态之间原本高的能屏障。研究将不仅包括纯系统（包含一种类型的多面体颗粒），还包括二元混合物中相变的热力学和动力学。要研究的颗粒包括可以在实验中产生的多面体（立方体，cuboctahedra，截断的八面体和八面体），以及这些混合物（包括球形颗粒）。模拟将对混合物的热力学行为进行建模，并将使用向前通量采样方法的新阶参数和变体来模拟相变的动力学。