Diameter Controllable Separation of Single-Walled Carbon Nanotubes by Simply Changing the Metal in
Naoki Komatsu1, Xinyi Fu2, Takuya Hayashi1
1Graduate School of Human and Environmental Studies, Kyoto University, Sakyo-ku, Kyoto, 606-8501, Japan.
Abstract:
Carbon nanotubes (CNTs) possess unique electronic and optical properties that are highly dependent on their structures. Therefore, diameter-selective synthesis and separation are meaningful for a wide range of their applications. Although various methods have been developed for CNT separations, challenges still remain in more efficient discrimination for diameters and removal of dispersants. Here, we present a novel approach for size-tunable diameter separation of single-walled carbon nanotubes (SWNTs) using metal-coordinating supramolecular polymers (M-PNB) consisting of phenanthroline-based nanobrackets (PNB) and metal ions (M). The helical wrapping of SWNTs with M-PNB is confirmed by transmission electron microscopy (TEM) analysis. Interestingly, Pd(II) and Co(II) ions with PNB show the large difference in diameter preference to the smaller (0.90 - 0.92 nm) and the larger (0.97 - 1.10 nm) diameters, respectively. Moreover, the combination of these two metal ions in M-PNB is found to enhance the selectivity to the specific (n,m)-SWNTs. This method offers not only size-tunable diameter selectivity but also significant improvements in extraction efficiency and the facile and thorough removal of the host molecules as compared to previous techniques.
