Abstract Surfactant-assisted exfoliation of multi-walled carbon nanotubes (MWNTs) in aqueous solution have become a common procedure to generate high fraction of individualized nanotubes. Since well-controlled experimental methodologies and reliable comparative metrics are scarce, a systematic research was conducted in order to analyze the dispersibility and the dispersing mechanisms of MWNTs in aqueous solutions of various surfactants. The concentration of dispersed MWNTs was accurately measured for a wide range of surfactant concentration, using combined UV–vis spectroscopy and thermogravimetric analysis (TGA). The obtained dispersibility results indicated that the highest dispersion concentration and efficiency is achieved in the SDBS-assisted MWNTs dispersion. Furthermore, the nanotube morphology and surfactant properties can be evaluated and rationalized by analyzing the dispersed nanotube mass and the surfactant amount per nanotube surface area. The amount of dispersed MWNTs remaining after varying levels of sonication and centrifugation was investigated, and a controllable sonication-centrifugation method for the preparation of well-dispersed MWNTs was established. The experimental data of the concentration of MWNTs dispersions versus centrifugation speed (ω) are fitted reasonably well by a Boltzmann function. The SDBS-assisted MWNTs dispersion will be more susceptible to the high centrifugal speed,while PVP-assisted MWNTs dispersion will be sediment fast at the mild centrifugation. The distributions of diameter and length of MWNTs at maximum dispersibility show that the sizes for the MWNTs dispersed by SDBS are much more polydisperse. The results further suggest that preparation of controllable carbon nanotubes morphology and design of rational configuration of surfactants are the key factors for increasing the dispersion stability and maximum concentration of well-dispersed MWNT.

中文翻译：

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多壁碳纳米管在各种分散剂水溶液中的分散浓度和粒径分布的系统研究

摘要 在水溶液中表面活性剂辅助剥离多壁碳纳米管 (MWNTs) 已成为生成高比例个性化纳米管的常用方法。由于缺乏控制良好的实验方法和可靠的比较指标，因此进行了系统研究，以分析 MWNT 在各种表面活性剂水溶液中的分散性和分散机制。使用组合的紫外-可见光谱和热重分析 (TGA)，可以准确测量各种表面活性剂浓度的分散 MWNT 的浓度。获得的分散性结果表明，在 SDBS 辅助的 MWNTs 分散中实现了最高的分散浓度和效率。此外，可以通过分析分散的纳米管质量和每纳米管表面积的表面活性剂量来评估和合理化纳米管形态和表面活性剂特性。研究了不同程度的超声处理和离心后剩余的分散 MWNTs 的数量，并建立了用于制备分散良好的 MWNTs 的可控超声离心方法。MWNT 分散体浓度与离心速度 (ω) 的实验数据通过 Boltzmann 函数拟合得相当好。SDBS辅助MWNTs分散对高离心速度更敏感,而PVP辅助MWNTs分散在温和离心时沉降较快。最大分散性下 MWNTs 的直径和长度分布表明，SDBS 分散的 MWNTs 的尺寸更分散。结果进一步表明，可控碳纳米管形貌的制备和表面活性剂合理构型的设计是提高分散良好的多壁碳纳米管的分散稳定性和最大浓度的关键因素。