AC electric field-induced alignment and long-range assembly of multi-wall carbon nanotubes inside aqueous media.
AC electric field-induced alignment and long-range assembly of multi-wall carbon nanotubes inside aqueous media.
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交流电场诱导多壁碳纳米管在水介质中的排列和长距离组装。
DOI：
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发表时间：
2007
影响因子：
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通讯作者：
A. Docoslis
中科院分区：
文献类型：
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作者：
Zhihui Guo;J. A. Wood;Krista L. Huszarik;Xiao;A. Docoslis
本文研究了多壁碳纳米管（MWCNT）在三维电极形成的交流电场中的行为。采用显微观察和在线测量悬浮电阻率相结合的方法，研究了碳纳米管在非离子表面活性剂作用下稳定悬浮在水中的响应。研究发现，外加交流电场对MWCNTs产生极化效应，使其单向定向并端到端接触，从而形成空间分布的、远距离的、三维的、横跨整个电极间隙的导电结构。形成的结构的长度，在目前的情况下大约是单个碳纳米管的30倍，可以通过调整电极之间的间距来控制。实验考察了MWCNT浓度、外加电压、交流场频和电极表面形貌等主要实验参数对悬浮性能的影响。结果表明，施加电压值、交流场频率和碳纳米管浓度分别在4-40 Vptp、10 Hz-5 MHz和0.001-2.0 wt%范围内。虽然较高的电场强度会加速排列结构的形成，但较高的频率值会导致悬浮液表现出较小的电阻率。碳纳米管分散体暴露在交流电场中，即使使用低至0.005 wt%的碳纳米管浓度，其电阻率也会降低100倍或更多。
The present work examines the behavior of multiwall carbon nanotubes (MWCNT) inside AC electric fields created by three-dimensional electrodes. The response of carbon nanotubes stably suspended in water with the aid of a nonionic surfactant is monitored by combining microscopic observations with on-line measurements of the suspension resistivity. It is found that polarization effects induced by the externally applied AC electric field on MWCNTs can cause their unidirectional orientation and end-to-end contact that result in formations of spatially distributed, long-range, three-dimensional and electrically conducting structures that span the entire gap between the electrodes. The length of the formed structures, which in the present case was approximately 30 times larger than that of an individual carbon nanotube, can be controlled by adjusting the spacing between the electrodes. The influence of main experimental parameters, namely, MWCNT concentration, applied voltage, AC field frequency, and electrode surface topography on the suspension behavior is experimentally examined. Results are demonstrated for applied voltage values, AC field frequencies, and carbon nanotube concentrations in the range 4-40 Vptp, 10 Hz-5 MHz, and 0.001-2.0 wt%, respectively. While higher electric field strengths accelerate the formation of aligned structures, higher frequency values were found to result in suspensions that exhibit smaller electrical resistivity. Carbon nanotube dispersions exposed to an AC electric field exhibit a 100-fold or more decrease in their electrical resistivity, even when carbon nanotube concentrations as low as 0.005 wt% are used.