Drying-mediated self-assembly of nanoparticles
Drying-mediated self-assembly of nanoparticles
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DOI：
10.1038/nature02087
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发表时间：
2003-11-20
期刊：
影响因子：
64.8
通讯作者：
Brus, LE
中科院分区：
文献类型：
--
作者：
Rabani, E;Reichman, DR;Brus, LE
远离平衡的系统可以表现出复杂的过渡结构，即使平衡波动是平凡的（1，2）。最近，在溶剂的不可逆蒸发过程中，钝化纳米晶体的薄膜溶液证明了这种现象的一个引人注目的例子（3-14）。在溶液中有效筛选的纳米晶体之间相对较弱的吸引力随着溶剂蒸发而变得明显，引发复杂的缓慢演变的结构的组装（4）。虽然这种聚集过程的某些方面可以单独用热力学参数来解释（6），但原则上它是一个非平衡过程（7）。这一过程的一个代表，从一个稠密的“液体”和稀释的“蒸汽”之间的相分离引起捕捉实验（3）中观察到的一些行为，但完全忽略了溶剂波动的作用，这可能是相当大的纳米长度尺度（15）。在这里，我们提出了一个粗粒度的纳米粒子自组装模型，明确包括蒸发溶剂的动力学。使用该模型的模拟不仅解释了所有观察到的空间和时间模式，而且还预测了尚未探索的网络结构。两种不同的机制出现，对应的蒸发动力学的均匀和非均匀的限制。我们的计算显示了溶剂，纳米颗粒尺寸（和身份）和热力学状态的不同选择如何引起最终结构的各种形态。由此产生的指导设计统计图案的纳米粒子阵列表明，自发组织的纳米器件制造的可能性。
Systems far from equilibrium can exhibit complex transitory structures, even when equilibrium fluctuations are mundane(1,2). A dramatic example of this phenomenon has recently been demonstrated for thin-film solutions of passivated nanocrystals during the irreversible evaporation of the solvent(3-14). The relatively weak attractions between nanocrystals, which are efficiently screened in solution, become manifest as the solvent evaporates, initiating assembly of intricate, slowly evolving structures(4). Although certain aspects of this aggregation process can be explained using thermodynamic arguments alone(6), it is in principle a non-equilibrium process(7). A representation of this process as arising from the phase separation between a dense nanocrystal 'liquid' and dilute nanocrystal 'vapour' captures some of the behaviour observed in experiments(3), but neglects entirely the role of solvent fluctuations, which can be considerable on the nanometre length scale(15). Here we present a coarse-grained model of nanoparticle self-assembly that explicitly includes the dynamics of the evaporating solvent. Simulations using this model not only account for all observed spatial and temporal patterns, but also predict network structures that have yet to be explored. Two distinct mechanisms of ordering emerge, corresponding to the homogeneous and heterogeneous limits of evaporation dynamics. Our calculations show how different choices of solvent, nanoparticle size (and identity) and thermodynamic state give rise to the various morphologies of the final structures. The resulting guide for designing statistically patterned arrays of nanoparticles suggests the possibility of fabricating spontaneously organized nanoscale devices.