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首页> 外文期刊>RSC Advances >Key role of the linker in pyrene-linker-carboxylate surfactants for the efficient aqueous dispersion of multiwalled carbon nanotubes
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Key role of the linker in pyrene-linker-carboxylate surfactants for the efficient aqueous dispersion of multiwalled carbon nanotubes

机译：接头在芘 - 接头 - 羧酸盐表面活性剂中的关键作用，用于多壁碳纳米管的有效水分散体

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摘要

This study establishes that the structure of the linker group between the hydrophobic and hydrophilic units in the new surfactants 1-13 plays an important role in the dispersibility of multiwalled carbon nanotubes (MWNTs) in water. The systematic variation of the linker group in amphiphilic surfactants for carbon nanotubes has not been previously investigated. In the present series, the hydrophobic unit is derived from pyrene, the hydrophilic unit comprises 1-9 carboxylate groups and the linker is based on amide or ether moieties. The resulting MWNT-surfactant dispersions, up to concentrations and efficiencies of ca. 160 mg L-1 and almost 50%, respectively, have been characterised by UV-vis absorption spectroscopy studies which provide detailed structure-property relationships, while transmission electron microscopy (TEM) was used to confirm that the MWNTs were well dispersed. For many of the new surfactants enhanced dispersion efficiency is observed compared to commercial surfactants. The efficiency of the dispersion is affected by the presence, functionality and particularly the length of the linker, and also the number of terminal carboxylate units. The marked effect of sodium, potassium and calcium cations on the dispersion behaviour is explained by interactions between the metal ions and the surfactant and an ionic screening mechanism. We also demonstrate that the dispersibility of the MWNT-surfactant dispersions can be reversibly switched 'off' and 'on' by addition of acid and base, respectively. The experimental results are supported by theoretical calculations of solvation energy DES. This study represents a significant advance in the design of multi-functional surfactants for efficient aqueous dispersions of carbon-based materials.
机译：该研究确定新型表面活性剂1-13中疏水性和亲水单元之间的接头组的结构在水中多壁碳纳米管（MWNT）的分散性中起重要作用。预先研究了碳纳米管的两亲硅胶表面活性剂中的连接基团的系统变化。在本系列中，疏水单元衍生自芘，亲水单元包含1-9个羧酸盐基团，并且接头基于酰胺或醚部分。得到的MWNT-表面活性剂分散体，达到CA的浓度和效率。分别为160mg L-1和近50％的特征在于UV-Vis吸收光谱研究，其提供了详细的结构性质关系，而透射电子显微镜（TEM）用于确认MWNT良好分散。对于许多新的表面活性剂，与商业表面活性剂相比，观察到增强的分散效率。分散的效率受连接内的存在，功能和特别是链接的长度的影响，以及末端羧酸盐单元的数量。通过金属离子和表面活性剂与离子筛选机构之间的相互作用来解释钠，钾和钙阳离子对分散行为的标记作用。我们还证明，通过加入酸和基础，MWNT-表面活性剂分散体的分散性可以分别可逆地切换“OFF”和'ON'。通过溶剂化能量DES的理论计算支持实验结果。该研究代表了多功能表面活性剂的设计中有效的碳基材料水分散体的显着进展。

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