Impact of the molecular architecture of polycarboxylate superplasticizers on the dispersion of multi-walled carbon nanotubes in aqueous phase
Impact of the molecular architecture of polycarboxylate superplasticizers on the dispersion of multi-walled carbon nanotubes in aqueous phase
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DOI：
10.1007/s10853-016-0522-3
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发表时间：
2017-02-01
影响因子：
4.5
通讯作者：
Leonhardt, Albrecht
中科院分区：
文献类型：
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作者：
Liebscher, Marco;Lange, Alex;Leonhardt, Albrecht
阐述了高效水泥分散剂甲基丙烯酸酯基聚羧酸酯（PCE）分散碳纳米管（CNT）的作用机理。PCE的这种双重功能节省了引入额外的表面活性剂，这可能会在水泥基基质中引起严重的不良反应。合成了八种具有明确结构的PCE，通过凝胶渗透色谱对其进行了表征，并评估了它们对CNT分散能力的影响。PCE的变化系统相对于它们的主链长度，接枝密度，和侧链长度。使用光学显微镜，发现在CNT：PCE = 1：1的质量比下，取决于PCE结构，在宏观分散体的状态中表现出明显的差异。然而，PCE结构和分散效率之间的明确的相关性不能建立。随后的一项研究应用了等量的PCE分子，揭示了个体PCE分散性的明显差异。最有效的PCE由长主链和高侧链密度组成。较低的侧链密度以及短的主链导致CNT分散能力的显著降低。关于侧链长度，没有发现显着的效果。最后，提出了一个模型的分散机制，导致解聚的碳纳米管。
The working mechanism of carbon nanotube (CNT) dispersion by distinct methacrylate ester-based polycarboxylates (PCEs), all of which are highly efficient cement dispersants, was elucidated. Such duplex functionality of the PCE saves introducing an extra surfactant, which might cause severe adverse reactions in cement-based matrices. Eight PCEs exhibiting well-defined architectures were synthesized, characterized by gel permeation chromatography, and their influence on the dispersion capability of CNTs was assessed. The PCEs varied systematically with respect to their backbone length, grafting density, and side-chain length. Using optical microscopy, it was found that at a mass ratio of CNT:PCE = 1:1, pronounced differences manifested themselves in the state of the macro-dispersions, depending on the PCE architecture. However, a clear correlation between PCE structure and dispersing efficiency could not be established. A subsequent study applying equivalent numbers of PCE molecules revealed clear differences in the individual PCEs' dispersibilities. The most efficient PCEs consisted of a long backbone combined with a high side-chain density. Lower side-chain densities as well as short backbones resulted in pronounced reduction in CNT-dispersing ability. Regarding side-chain length, no significant effect was found. Finally, a model for the dispersing mechanism leading to deagglomeration of the CNTs was proposed.