论文标题
聚合胶体纳米晶的液体样生长
Liquid-like growth of colloidal nanocrystals of coalescence
论文作者
论文摘要
我们对晶体生长的理解是由经典描述主导的，该描述是由过饱和驱动的单个原子或分子加入晶体方面的。结果，硬物质的生长仍然被认为与软物质的生长（如聚合物或液体）根本无与伦比。通过实验和建模的结合，我们在这里展示了在没有聚结（例如乳液中的液滴）的情况下，胺封闭的PBS胶体纳米颗粒如何生长。具体而言，我们（i）确定，尽管颗粒的空间稳定，但晶体晶体结合的速率（10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-2至10^-1 m^-1*s^-1），与双向分子反应相媲美，并与率的新型反应率相比（从而为II的新型驾驶员提供），而不是在化学量中，而不是化学量的率（II）。晶体结合的步骤使我们提出了设计规则以控制它，并且（iii）展示了一个简单的两参数模型，该模型可以定量地预测该过程及其对配体的依赖性。最后，我们使用布朗动力学模拟来展示与平均自由路径相比，拥挤效应和相对较大的颗粒尺寸如何解释了这些非常大的合并速率，同时，对以前报道的定向依恋过程的令人难以置信的低较低激活能量值。
Our understanding of the growth of crystals is dominated by the classical description according to which individual atoms or molecules, driven by supersaturation, add to crystal facets. As a result, the growth of hard matter is still mostly considered to be fundamentally incomparable to the growth of soft matter, like polymers or liquids. By a combination of experiment and modeling we here show how amine-capped PbS colloidal nanoparticles grow in the absence of supersaturation by coalescence, like droplets in an emulsion. Specifically, we (i) determine that the rates of crystal-crystal coalescence are remarkably high (10^-2 to 10^1 M^-1*s^-1) in spite of the steric stabilization of the particles, and are comparable to those of bimolecular reactions, (thereby providing a new avenue for the development of a form of chemistry where the reactants are colloids rather than molecules), (ii) elucidate the rate limiting steps of crystal-crystal coalescence leading us to propose design rules to control it, and (iii) demonstrate a simple, two-parameter model that predicts quantitatively this process and its dependence on the ligands. Lastly, we use Brownian dynamics simulations to show how crowding effects and the relatively large size of the particles compared to their mean free path explain these remarkably large rates of coalescence and, at the same time, the puzzlingly low values of activation energy previously reported for oriented attachment processes.
