Side reactions in controlling the quality, yield, and stability of high quality colloidal nanocrystals
Side reactions in controlling the quality, yield, and stability of high quality colloidal nanocrystals
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DOI：
10.1021/ja053151g
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发表时间：
2005-09-28
影响因子：
15
通讯作者：
Peng, XG
中科院分区：
文献类型：
--
作者：
Chen, YF;Kim, M;Peng, XG
以ZnO为模型体系，研究了高质量纳米胶体晶体形成过程中副反应的影响。在这种情况下，一个不可逆的副反应，形成酯，被确定为伴随ZnO纳米晶体的形成，通过硬脂酸锌和过量的醇在烃溶剂中在高温下的化学反应。这种不可逆的副反应使得所得的纳米晶体稳定并且具有几乎统一的产率，而不管它们的尺寸、形状和尺寸/形状分布。由于可能的单体的极低溶解度/稳定性，停止奥斯特瓦尔德熟化和颗粒内熟化，因为溶液中的所有游离配体被副反应消耗。然而，关注高质量纳米晶体生长所需的尺寸分布和1D生长仍然可以发生高产率反应。加入少量硬脂酸或膦酸后，ZnO纳米晶立即发生部分溶解。虽然过量的醇不能与所得的锌膦酸盐反应，但它可以迫使新形成的硬脂酸锌逐渐但完全地回到现有的纳米晶体上。本报告中的结果表明，副反应通过影响其质量、产率和生长条件下的稳定性，对高质量纳米晶体的形成极其重要。由于它们在文献中缺乏信息和明显的实际优势，伴随纳米晶体形成的副反应的研究对于与结晶相关的基础科学和高质量纳米晶体的工业生产都是重要的。
Effects of side reactions during the formation of high quality colloidal nanocrystals were studied using ZnO as a model system. In this case, an irreversible side reaction, formation of esters, was identified to accompany formation of ZnO nanocrystals through the chemical reaction between zinc stearate and an excess amount of alcohols in hydrocarbon solvents at elevated temperatures. This irreversible side reaction made the resulting nanocrystals stable and with nearly unity yield regardless of their size, shape, and size/shape distribution. Ostwald ripening and intraparticle ripening were stopped due to the extremely low solubility/stability of the possible monomers because all free ligands in the solution were consumed by the side reaction. However, focusing on size distribution and 1D growth that are needed for the growth of high quality nanocrystals could still occur for high yield reactions. Upon the addition of a small amount of stearic acid or phosphonic acid, immediate partial dissolution of ZnO nanocrystals took place. Although the excess alcohol could not react with the resulting zinc phosphonic acid salt, it could force the newly formed zinc stearate gradually but completely back onto the existing nanocrystals. The results in this report indicate that side reactions are extremely important for the formation of high quality nanocrystals by affecting their quality, yield, and stability under growth conditions. Due to their lack of information in the literature and obvious practical advantages, studies of side reactions accompanying formation of nanocrystals are important for both fundamental science related to crystallization and industrial production of high quality nanocrystals.