Université Pierre et Marie Curie, UMR 7070, LM2N, 4 place Jussieu 75005 Paris, France.
J Phys Chem B. 2013 Apr 25;117(16):4510-6. doi: 10.1021/jp308608g. Epub 2012 Nov 6.
Under solvent saturation, a precipitation of full-grown supracrystals on the one hand and the formation of well-defined supracrystalline films at the air-liquid interface on the other hand were previously observed for the first time (J. Am. Chem. Soc.2012, 134, 3714-3719). Here, these two simultaneous growth processes are studied by additional experiments and by Brownian dynamics simulations. The thickness of the supracrystalline films and the concentration of free nanocrystals within the solution are measured as a function of the nanocrystal size. The simulations show that the first process of supracrystal growth is due to a homogeneous nucleation favored by solvent-mediated ligand interactions, while the second one is explained in terms of a diffusion process caused by a decrease in the surface energy when the particles penetrate the air-liquid interface. It is also verified that the presence of thiol molecules at the air-solution interface does not hinder the formation of supracrystalline films.
在溶剂饱和的情况下，此前曾首次观察到完整的过饱和晶体一方面在沉淀，另一方面在气液界面形成具有良好定义的过饱和晶体薄膜（美国化学学会志，2012 年，134，3714-3719）。在这里，通过额外的实验和布朗动力学模拟研究了这两个同时发生的生长过程。测量了过饱和晶体薄膜的厚度和溶液中游离纳米晶体的浓度作为纳米晶体尺寸的函数。模拟表明，第一个过饱和晶体生长过程是由于溶剂介导的配体相互作用有利于均相成核，而第二个过程则可以用粒子穿透气液界面时表面能降低引起的扩散过程来解释。还验证了在溶液-空气界面存在硫醇分子不会阻碍过饱和晶体薄膜的形成。
