Polymers Division, National Institute of Standards in Technology , 100 Bureau Drive, Gaithersburg, Maryland 20899-8542, United States.
ACS Nano. 2011 Oct 25;5(10):8258-66. doi: 10.1021/nn2029549. Epub 2011 Sep 13.
Emerging applications require single-wall carbon nanotubes (SWCNTs) of well-defined length. Yet the use of length-defined SWCNTs is limited, in part due to the lack of an easily accessible materials preparation method. Here, we present a new strategy for SWCNT length fractionation based on molecular crowding induced cluster formation. We show that the addition of polyethylene glycol (PEG) as a crowding agent into DNA-wrapped SWCNT dispersion leads to the formation of reversible, nematic, and rodlike microclusters, which can be collected by gentle centrifugation. Since shorter SWCNTs form clusters at higher polyethylene glycol concentration, gradual increase in PEG concentration results in length fractionated SWCNTs. Using atomic force microscopy (AFM) we show that fractions with average lengths of 60-500 nm and standard deviations of 30-40% can be obtained. The concept of molecular-crowding-based fractionation should be applicable to other nanoparticle dispersions.
新兴应用需要具有明确长度的单壁碳纳米管 (SWCNT)。然而，由于缺乏易于获得的材料制备方法，长度可控的 SWCNT 的应用受到限制。在这里，我们提出了一种基于分子拥挤诱导聚集体形成的 SWCNT 长度分级新策略。我们表明，将聚乙二醇 (PEG) 作为拥挤剂添加到 DNA 包裹的 SWCNT 分散体中会导致可逆的、向列的和棒状的微聚集体的形成，这些微聚集体可以通过温和的离心收集。由于较短的 SWCNT 在较高的聚乙二醇浓度下形成聚集体，因此逐渐增加 PEG 浓度会导致 SWCNT 分级。使用原子力显微镜 (AFM)，我们表明可以获得平均长度为 60-500nm 且标准偏差为 30-40%的分数。基于分子拥挤的分级概念应该适用于其他纳米颗粒分散体。
