The Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia 30332, United States.
J Am Chem Soc. 2013 Feb 6;135(5):1941-51. doi: 10.1021/ja311503q. Epub 2013 Jan 28.
This article describes a robust method for the facile synthesis of small Ag nanocubes with edge lengths controlled in the range of 18-32 nm. The success of this new method relies on the substitution of ethylene glycol (EG)--the solvent most commonly used in a polyol synthesis--with diethylene glycol (DEG). Owing to the increase in hydrocarbon chain length, DEG possesses a higher viscosity and a lower reducing power relative to EG. As a result, we were able to achieve a nucleation burst in the early stage to generate a large number of seeds and a relatively slow growth rate thereafter; both factors were critical to the formation of Ag nanocubes with small sizes and in high purity (>95%). The edge length of the Ag nanocubes could be easily tailored in the range of 18-32 nm by quenching the reaction at different time points. For the first time, we were able to produce uniform sub-20 nm Ag nanocubes in a hydrophilic medium and on a scale of ∼20 mg per batch. It is also worth pointing out that the present protocol was remarkably robust, showing good reproducibility between different batches and even for DEGs obtained from different vendors. Our results suggest that the high sensitivity of synthesis outcomes to the trace amounts of impurities in a polyol, a major issue for reproducibility and scale up synthesis, did not exist in the present system.
本文描述了一种简便的方法，可用于合成边长为 18-32nm 的小 Ag 纳米立方体。这种新方法的成功依赖于将乙二醇（EG）——多元醇合成中最常用的溶剂——替换为二甘醇（DEG）。由于烃链长度的增加，DEG 的粘度比 EG 更高，还原能力更低。因此，我们能够在早期实现核的爆发，产生大量的晶核，随后生长速度相对较慢；这两个因素对于形成小尺寸、高纯度（>95%）的 Ag 纳米立方体都非常重要。通过在不同的时间点终止反应，可以很容易地将 Ag 纳米立方体的边长控制在 18-32nm 的范围内。我们首次在亲水介质中以批处理规模约为 20mg 生产出均匀的亚 20nm 的 Ag 纳米立方体。值得指出的是，本方法具有很好的稳健性，不同批次之间甚至不同供应商提供的 DEG 之间都具有很好的重现性。我们的结果表明，多元醇中痕量杂质对合成结果的高度敏感性，这是重现性和放大合成的主要问题，在本体系中并不存在。
