Multiple Roles of Polyethylenimine during Synthesis of 10 nm Thick Continuous Silver Nanoshells.,Langmuir

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Multiple Roles of Polyethylenimine during Synthesis of 10 nm Thick Continuous Silver Nanoshells.
Langmuir ( IF 3.7 ) Pub Date : 2020-04-02 , DOI: 10.1021/acs.langmuir.9b03096
San San Maw ₁ , Satoshi Watanabe ₁ , Minoru T Miyahara ₁

Affiliation

Silica@silver core–shell particles (silver nanoshells) present a wide range of applications, owing to their unique optical, chemical, and surface plasmon resonance (SPR) properties. Because SPR properties are mainly determined by shell thickness, precise shell thickness control is required. However, the synthesis of continuous nanoshells less than 10 nm thickness is still a challenge. In this study, we overcame this challenge by using polyethyleneimine (PEI) during the shell growth step of the seed-mediated growth method. We determined that the addition of PEI significantly slowed the shell growth reaction and facilitated the formation of uniform shells, which allowed us to synthesize 9.8 nm thick complete silver nanoshells. The SPR absorptions of the resultant nanoshell suspensions remained almost unchanged for 15 days. Therefore, we demonstrated that PEI molecules played three different roles during the shell growth process: reaction-rate regulators, shell growth facilitators, and resultant suspension stabilizers. The shell thickness was tuned from 9.8 to 29.5 nm by simply varying the silver-ion concentration. A key factor was the amount of added PEI because excess PEI would result in the formation of silver nanoparticles in the bulk solution phase, while too little PEI would produce incomplete shells. The optimum mass ratio of PEI-to-silica particles was determined to be 1.0 for the experimental conditions in this study. The mixing sequence of the reaction solutions was also important because PEI had to be mixed with silica particles first to ensure that the PEI molecules get adsorbed on the surface of silica and accommodated silver ions via the coordination interactions between the amine groups of the PEI molecules and silver ions. The reaction that involves the use of PEI could lead to establishing a simple and robust synthesis technique for silver nanoshells.

中文翻译：

聚乙烯亚胺在10 nm厚连续银纳米壳的合成过程中的多重作用。

二氧化硅@银核-壳颗粒（银纳米壳）由于其独特的光学，化学和表面等离振子共振（SPR）特性而具有广泛的应用。由于SPR特性主要取决于外壳厚度，因此需要精确的外壳厚度控制。然而，合成厚度小于10 nm的连续纳米壳仍然是一个挑战。在这项研究中，我们通过在种子介导的生长方法的壳生长步骤中使用聚乙烯亚胺（PEI）克服了这一挑战。我们确定，PEI的添加显着减慢了壳的生长反应并促进了均匀壳的形成，这使我们能够合成9.8 nm厚的完整银纳米壳。所得纳米壳悬浮液的SPR吸收在15天内几乎保持不变。因此，我们证明了PEI分子在壳的生长过程中发挥了三种不同的作用：反应速率调节剂，壳的生长促进剂和最终的悬浮稳定剂。通过简单地改变银离子浓度，将壳厚度从9.8nm调节至29.5nm。一个关键因素是添加的PEI的数量，因为过量的PEI会导致在整体溶液相中形成银纳米颗粒，而太少的PEI则会产生不完整的壳。对于本研究中的实验条件，PEI与二氧化硅颗粒的最佳质量比确定为1.0。反应溶液的混合顺序也很重要，因为必须先将PEI与二氧化硅颗粒混合，以确保PEI分子通过PEI分子的胺基团与PEI分子之间的配位相互作用而吸附在二氧化硅表面并容纳银离子。银离子。涉及使用PEI的反应可导致建立一种简单而稳健的银纳米壳合成技术。

更新日期：2020-04-02

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