Limits...
Non-covalent polymer wrapping of carbon nanotubes and the role of wrapped polymers as functional dispersants

View Article: PubMed Central - PubMed

ABSTRACT

Carbon nanotubes (CNTs) have been recognized as a promising material in a wide range of applications from biotechnology to energy-related devices. However, the poor solubility in aqueous and organic solvents hindered the applications of CNTs. As studies have progressed, the methodology for CNT dispersion was established. In this methodology, the key issue is to covalently or non-covalently functionalize the surfaces of the CNTs with a dispersant. Among the various types of dispersions, polymer wrapping through non-covalent interactions is attractive in terms of the stability and homogeneity of the functionalization. Recently, by taking advantage of their stability, the wrapped-polymers have been utilized to support and/or reinforce the unique functionality of the CNTs, leading to the development of high-performance devices. In this review, various polymer wrapping approaches, together with the applications of the polymer-wrapped CNTs, are summarized.

No MeSH data available.


PFO derivatives and the analogs selectively disperse s-SWCNTs reported from our group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
getmorefigures.php?uid=PMC5036478&req=5

Figure 7: PFO derivatives and the analogs selectively disperse s-SWCNTs reported from our group.

Mentions: Compared to the other separation techniques, such as gel chromatography [89–93] and density gradient ultracentrifugion (DGU) [94, 95], PFO-based extraction of s-SWCNTs is quite attractive due to its simplicity as well as its high purity [96]. Very importantly, the tailorable design of the PFO allowed researchers to develop a wide variety of PFO-based copolymers for the separation of the SWCNTs [97]. Indeed, we demonstrated that many monomers are incorporated into the PFO for the s-SWCNT extraction (figure 7) [98–105]. Thanks to the high purity of the obtained s-SWCNTs, the extracted s-SWCNTs are considered as a promising material for next-generation SWCNT-based semiconducting devices. Izard et al reported an on/off ratio greater than 105 in a field effect transistor (FET) fabricated from the s-SWCNT network extracted by PFO wrapping, while the unsorted SWCNTs gave only 102 ∼ 103 [61]. In 2010, Bindl et al reported light harvesting in the near-IR (NIR) region using PFO-sorted s-SWCNTs as the chromophore, where C60 was incorporated as the acceptor (figure 8) [106–108]. In these examples, due to the high-quality separation of the s-SWCNTs by PFO, a significant enhancement of the efficiency was obtained compared to the device fabricated with unsorted SWCNTs. However, in these applications, the wrapped PFOs were used only for the separation but remained wrapped in the devices. It was pointed out that the organic residual remaining on the surface of CNTs often diminishes the performance of the devices, especially for semiconducting applications [94], and in such cases the complete removal of the wrapped polymers is required. For instance, Bisri et al developed a two-step ultracentrifugation method to remove the polymer from the polymer-dispersed CNT solution [62]. In this method, they obtained a polymer less than 7 mg mL−1, but wrapping of the polymer was so tight that the perfect removal of the polymer was not possible. Recently, we have designed the fluorene monomer carrying two ligand units (PhenFO), which polymerize in the presence of metal ions to give a PFO derivative (CP-M) by coordination (figure 7). In this system, the wrapped PFO was easily removed by the addition of an acid to decompose the coordination after the extraction of the s-SWCNTs (figure 9) [109]. As the result, complete removal of the polymer was realized.


Non-covalent polymer wrapping of carbon nanotubes and the role of wrapped polymers as functional dispersants
PFO derivatives and the analogs selectively disperse s-SWCNTs reported from our group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC5036478&req=5

Figure 7: PFO derivatives and the analogs selectively disperse s-SWCNTs reported from our group.
Mentions: Compared to the other separation techniques, such as gel chromatography [89–93] and density gradient ultracentrifugion (DGU) [94, 95], PFO-based extraction of s-SWCNTs is quite attractive due to its simplicity as well as its high purity [96]. Very importantly, the tailorable design of the PFO allowed researchers to develop a wide variety of PFO-based copolymers for the separation of the SWCNTs [97]. Indeed, we demonstrated that many monomers are incorporated into the PFO for the s-SWCNT extraction (figure 7) [98–105]. Thanks to the high purity of the obtained s-SWCNTs, the extracted s-SWCNTs are considered as a promising material for next-generation SWCNT-based semiconducting devices. Izard et al reported an on/off ratio greater than 105 in a field effect transistor (FET) fabricated from the s-SWCNT network extracted by PFO wrapping, while the unsorted SWCNTs gave only 102 ∼ 103 [61]. In 2010, Bindl et al reported light harvesting in the near-IR (NIR) region using PFO-sorted s-SWCNTs as the chromophore, where C60 was incorporated as the acceptor (figure 8) [106–108]. In these examples, due to the high-quality separation of the s-SWCNTs by PFO, a significant enhancement of the efficiency was obtained compared to the device fabricated with unsorted SWCNTs. However, in these applications, the wrapped PFOs were used only for the separation but remained wrapped in the devices. It was pointed out that the organic residual remaining on the surface of CNTs often diminishes the performance of the devices, especially for semiconducting applications [94], and in such cases the complete removal of the wrapped polymers is required. For instance, Bisri et al developed a two-step ultracentrifugation method to remove the polymer from the polymer-dispersed CNT solution [62]. In this method, they obtained a polymer less than 7 mg mL−1, but wrapping of the polymer was so tight that the perfect removal of the polymer was not possible. Recently, we have designed the fluorene monomer carrying two ligand units (PhenFO), which polymerize in the presence of metal ions to give a PFO derivative (CP-M) by coordination (figure 7). In this system, the wrapped PFO was easily removed by the addition of an acid to decompose the coordination after the extraction of the s-SWCNTs (figure 9) [109]. As the result, complete removal of the polymer was realized.

View Article: PubMed Central - PubMed

ABSTRACT

Carbon nanotubes (CNTs) have been recognized as a promising material in a wide range of applications from biotechnology to energy-related devices. However, the poor solubility in aqueous and organic solvents hindered the applications of CNTs. As studies have progressed, the methodology for CNT dispersion was established. In this methodology, the key issue is to covalently or non-covalently functionalize the surfaces of the CNTs with a dispersant. Among the various types of dispersions, polymer wrapping through non-covalent interactions is attractive in terms of the stability and homogeneity of the functionalization. Recently, by taking advantage of their stability, the wrapped-polymers have been utilized to support and/or reinforce the unique functionality of the CNTs, leading to the development of high-performance devices. In this review, various polymer wrapping approaches, together with the applications of the polymer-wrapped CNTs, are summarized.

No MeSH data available.