Materials World Network (MWN) for Particle-mediated Control Over Crystallization: From the Pre-nucleation Stage to the Final Crystal

将形成材料世界网络（MWN），以研究粒子介导的结晶机制，通过该机制产生介观晶体-在介观尺度上结构化的晶体。在生物矿物系统中，介晶形成是由生物分子介导的普遍现象，并导致与这些材料通常相关的分级组织。我们的最终目标是对这一过程的机械理解和一套指导仿生策略的原则，以创建分层组织的材料（例如生物陶瓷，光子固体，能量收集材料）。国际合作的附加值是，它通过将化学和介晶生长方面的专业知识与高分辨率原位成像、相互作用测量、结构确定以及从原子到介观尺度的建模和模拟能力相结合，促进了这一目标的实现。使用碳酸钙，氧化铁和硅酸钙水合物（C-S-H）系统与聚合物相结合，该项目将围绕关键科学问题进行三个重点：重点1：预成核阶段，初级纳米颗粒和中间相的成核-预成核簇的性质将使用离子电位测量，滴定和超离心来确定。它们的溶液相互作用动力学将通过液体细胞TEM探测。推力二：纳米晶体和介晶形成的有机介质之间的相互作用力-负责颗粒共取向和重取向的相互作用将通过动态力谱（DFS）和建模的组合来确定。DFS将提供一个方向依赖的晶体和聚合物相互作用的自由能的直接测量。实验测量得到分子建模的支持，这使我们能够确定有效相互作用的分子细节，并为推力3中的相场计算提供参数。推力3：成核后颗粒聚集和共取向--将用液池TEM和非原位HRTEM研究颗粒聚集的动力学、聚集颗粒的晶体取向随时间的变化以及介晶聚集体的结构演变。重点将放在区分定向附着和定向后随机聚集无论是通过整个粒子旋转或原子尺度的成熟。这些数据将比较相场模型的介晶组件，利用推力2中确定的相互作用能。

A Materials World Network (MWN) will be formed to investigate mechanisms of particle-mediated crystallization through which mesocrystals — crystals structured on the mesoscale — are created. In biomineral systems, mes-ocrystal formation is a widespread phenomenon mediated by biomolecules and leading to the hierarchical organization commonly associated with these materials. Our ultimate goal is a mechanistic understanding of this process and a set of principles to guide biomimetic strat-egies to create hierarchically organized materials (e.g. bioceramics, photonic solids, energy harvesting materials). The value added by the international collaboration is that it facilitates this goal by combining expertise in chemistry and growth of mesocrystals with capabilities in high-resolution in situ imaging, measurement of interactions, determination of structure, and modeling and simulation from the atomic to mesoscale. Using the calcium carbonate, iron oxide and calcium-silicate hydrate (C-S-H) systems combined with polymers, the project will pursue three thrusts, structured around the key scientific questions: Thrust 1: The pre-nucleation stage, nucleation of primary nanoparticles and intermediate phases - The nature of pre-nucleation clusters will be determined using ion potential measurements, titration and ultracentrifugation. Their solution interaction dynamics will be probed through liquid cell TEM. Thrust 2: Interactions forces between nanocrystals and organic mediators of mesocrystal formation – The interactions responsible for particle co-orientation and reorientation will be determined through a combination of dynamic force spectroscopy (DFS) and modeling. DFS will provide a direct measure of the free energy of the orientation dependent crystal-crystal and -polymer interactions. Experimental measurements are supported by molecular model-ing, which allows us to determine molecular details of the effective interactions and provides parameters for the phase field calculations in Thrust 3. Thrust 3: Post-nucleation particle ag-gregation and co-orientation – The kinetics of particle aggregation, crystallographic orienta-tions of the aggregating particles as a function of time, and structural evolution of mesocrys-talline aggregates will be investigated by liquid cell TEM and ex situ HRTEM. Emphasis will be placed on distinguishing between oriented attachment and orientation following random aggregation either through whole-particle rotation or atomic-scale ripening. These data will be compared to phase-field models of mesocrystal assembly that utilize the interaction energies determined in Thrust 2.