銀奈米液滴在奈米碳管上的毛細現象

Capillary Phenomenon of Silver Nanodroplets on Carbon Nanotubes

陳延松(Yen-Song Chen)

指導教授 ： 張嘉升

國立臺灣大學/理學院/物理研究所/博士(2012年)

https://doi.org/10.6342/NTU.2012.01263

摘要

液體因毛細作用被毛細管所吸收的現象很普遍地發生在巨觀的世界中，這個現象很簡單地透過在管中的液面為凹面或凸面情況以及接觸角的值來描述。在這篇研究中，我們想要測試毛細作用的巨觀理論是否也能被應用到奈米尺度中，我們研究和觀察融化的銀奈米液滴被吸入多層奈米碳管中空腔體中的動態行為，毛細作用會發生在融化銀液滴平均直徑與碳管內直徑的比值在一個臨界值之下，透過有系統地對各種大小銀奈米液滴和不同碳管尺寸的搭配，我們觀察到隨著碳管內直徑從8 nm減小到2.5 nm時，發生毛細吸收的臨界值會從1.7變小至1.2，這結果暗示著奈米尺度下表現出來的尺寸相關的特性。這個發現對於了解奈米級毛細作用現象以及奈米碳管複合物的製作是非常重要的。在文中還記錄著透過連續毛細吸收融化的金屬銀奈米液滴的方法，可以製作填充在奈米碳管內具有特定長度的一維銀奈米線。

關鍵字

毛細作用 ； 奈米碳管 ； 銀 ； 奈米粒子 ； 奈米液滴 ； 奈米線

並列摘要

Capillarity, involving the absorption of a liquid by a tube, is a commonplace phenomenon in the macroscopic world. The phenomenon can be characterized by the contact angle formed between the meniscus and the tube. In this study, we would like to test if this macroscopic theory of capillarity could also be applied to the nanometer scale. We studied the dynamical behaviors of molten silver (Ag) nanodroplets drawn into the hollow cores of multiwall carbon nanotubes (MWCNTs). The capillary action occurrs when the ratio of the average diameter of a molten Ag droplet to that of a MWCNT’s inner core is below a critical value. With the systematic experiments on various size combinations of the Ag droplets and CNTs, we discover that the critical ratio value for absorption declines from 1.7 to 1.2 as the CNT’s inner diameter decreases from 8 nm to 2.5 nm, implying that capillarity at the nanometer scale exhibits a size-dependent nature. This finding is important for understanding the capillarity at the nanoscale and for applying it to the fabrication of CNT composites. By continuous capillary absorption of molten Ag nanodroplets, a one-dimensional Ag nanowire with specific length can be made in the CNT and shown in this article.

並列關鍵字

capillary ； carbon nanotube ； silver ； nanoparticle ； nanodroplet ； nanowire

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