Ionic Liquid Aggregation Mechanism for Nanoparticle Synthesis
Ionic Liquid Aggregation Mechanism for Nanoparticle Synthesis
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DOI：
10.1021/acs.jpcb.0c08908
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发表时间：
2021-01-14
影响因子：
3.3
通讯作者：
Saunders, Steven R.
中科院分区：
文献类型：
--
作者：
Bryant, Kristin;Hammond-Pereira, Ellis;Saunders, Steven R.
先前已经证明用甲硅烷基胺可逆离子液体（RevIL）合成纳米颗粒提供了传统纳米颗粒合成的独特替代方案，允许通过IL的可切换性质控制尺寸和容易地沉积到载体表面上。然而，纳米颗粒合成的机制仍然没有得到表征。RevIL的使用促进了尺寸受控的纳米颗粒的合成，而不使用另外的稳定剂（即，表面活性剂、配体和聚合物），其钝化纳米颗粒表面，这是传统上控制纳米颗粒尺寸所需要的。传统技术通常需要苛刻的活化步骤，最终影响纳米颗粒的尺寸和形态。虽然RevIL合成提供了一个很好的替代方案，因为它们不需要额外的活化步骤，但在这些系统中合成纳米颗粒的机制以前没有研究过。先前的工作假设用RevIL制备的纳米颗粒通过反胶束机制形成，其中纳米颗粒在有组织的胶束结构的水性核心内稳定和模板化。在这项工作中，DOSY-NMR被用来证明与3-氨丙基三乙基硅烷RevIL合成的纳米颗粒不是通过反胶束机制形成的，而是通过操纵RevIL结构和浓度来控制纳米颗粒尺寸的可切换聚集机制。此外，它示出了向RevIL系统中添加水对溶液中的离子液体分子的聚集行为具有不利影响，导致离子对的分解。然而，由于纳米颗粒还原可能比离子对的分解发生得更快，因此纳米颗粒尺寸不受纳米颗粒还原期间添加水的影响。
Nanoparticle synthesis with silylamine reversible ionic liquids (RevILs) has been previously demonstrated to offer unique alternatives to traditional nanoparticle syntheses, allowing for size control and facile deposition onto support surfaces via the switchable nature of the IL. However, the mechanism of nanoparticle synthesis remains uncharacterized. The use of RevILs facilitates the synthesis of size-controlled nanoparticles without the use of additional stabilizing agents (i.e., surfactants, ligands, and polymers) that passivate the nanoparticle surface, which are traditionally required to control the nanoparticle size. Traditional techniques often require harsh activation steps that ultimately impact nanoparticle size and morphology. While RevIL syntheses offer an excellent alternative, as they do not require additional activation steps, the mechanism through which nanoparticles are synthesized in these systems has not been studied previously. Preceding work hypothesized nanoparticles prepared with RevILs are formed via a reverse micelle mechanism, in which nanoparticles are stabilized and templated within the aqueous core of the organized micelle structures. In this work, DOSY-NMR is used to demonstrate that nanoparticles synthesized with 3-aminopropyltriethylsilane RevIL are not formed through a reverse micelle mechanism but rather a switchable aggregation mechanism that affords control over the nanoparticle size via manipulation of the RevIL structure and concentration. Furthermore, it is shown that the addition of water to RevIL systems has detrimental effects on the aggregation behavior of the ionic liquid molecules in solution, causing disassembly of the ion pairs. However, because nanoparticle reduction likely occurs faster than the disassembly of the ion pairs, nanoparticle size is unaffected by the addition of water during nanoparticle reduction.