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

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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.


(a) Selective deposition of CNTs based on electrostatic directed assembly. (b), (c) SEM images of (b) HfO2 and the (c) SiO2 area of the patterned substrate. Scale bars = 1 μm. (d) Selective deposition of CNT based on the metal-ligand directed assembly. (e), (f) SEM images of (e) Au and the (f) HfO2 area of the patterned substrate. Scale bars = 100 nm. Reprinted with permission from J M Lobez and A Afzali 2013 Chem. Mater.25 3662. Copyright 2013 American Chemical Society.
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Figure 23: (a) Selective deposition of CNTs based on electrostatic directed assembly. (b), (c) SEM images of (b) HfO2 and the (c) SiO2 area of the patterned substrate. Scale bars = 1 μm. (d) Selective deposition of CNT based on the metal-ligand directed assembly. (e), (f) SEM images of (e) Au and the (f) HfO2 area of the patterned substrate. Scale bars = 100 nm. Reprinted with permission from J M Lobez and A Afzali 2013 Chem. Mater.25 3662. Copyright 2013 American Chemical Society.

Mentions: When the wrapping polymers act as the pigment, light-harvesting systems using the CNTs as an acceptor can be fabricated [242]. The unique charge transport features of the CNTs provide an efficient percolation network with a highly efficient exciton dissociation in polymeric bulk heterojunctions with the polymer acting as the donor and the CNT as the acceptor. Based on this concept, poly(3-alkylthiophenes) have been widely used [110, 239]. In 2005, poly(3-octylthiophene) (P3OT) was reported to wrap the SWCNTs and improved the photovoltaic behavior by the photo-induced electron transfer at the P3OT/SWCNT interfaces [243]. The combination of poly(3-alkylthiophenes) and s-SWCNTs forms a heterojunction with a type-II band alignment in which the HOMO and LUMO of the donor are higher than those of the acceptor (figure 23) [244]. This band structure leads to exciton dissociation at the interface with an ultrafast charge transfer from the P3HT to the s-SWCNTs [244–247], and the s-SWCNTs can act as efficient acceptors at the interface [244]. The time-resolved microwave conductivity measurements revealed that the photoexcitation of P3HT results in long-lived carriers due to the efficient spatial separation at the SWCNT–P3HT interface, which readily move electrons away to avoid recombination [248]. Another advantage is that organization of P3HT induced by SWCNTs [249] leads to the improvement of the exciton diffusion as well as the charge mobility in a P3HT/SWCNT composite [250]. It is important to note that the key progress in this field is the developments of the extraction technology of the s-SWCNTs, such as DGU [251] and PFO wrapping [88], since the contamination of m-SWCNTs in the active layer have a detrimental impact on the photocurrent [245], and theoretical studies have predicted that the band alignment of the P3HT/m-SWCNT is unfavorable for charge separation [244]. By utilizing s-SWCNTs, Dabera et al revealed the ground-state electron transfer from s-SWCNT to P3HT in the P3HT-wrapped s-SWCNTs, which facilitated the hole transportation property of the s-SWCNTs. The hybrid was used as hole transport layers for bulk heterojunction organic photovoltaics, and the device showed the highest power conversion efficiency (PCE = 7.6%) [252].


Non-covalent polymer wrapping of carbon nanotubes and the role of wrapped polymers as functional dispersants
(a) Selective deposition of CNTs based on electrostatic directed assembly. (b), (c) SEM images of (b) HfO2 and the (c) SiO2 area of the patterned substrate. Scale bars = 1 μm. (d) Selective deposition of CNT based on the metal-ligand directed assembly. (e), (f) SEM images of (e) Au and the (f) HfO2 area of the patterned substrate. Scale bars = 100 nm. Reprinted with permission from J M Lobez and A Afzali 2013 Chem. Mater.25 3662. Copyright 2013 American Chemical Society.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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Figure 23: (a) Selective deposition of CNTs based on electrostatic directed assembly. (b), (c) SEM images of (b) HfO2 and the (c) SiO2 area of the patterned substrate. Scale bars = 1 μm. (d) Selective deposition of CNT based on the metal-ligand directed assembly. (e), (f) SEM images of (e) Au and the (f) HfO2 area of the patterned substrate. Scale bars = 100 nm. Reprinted with permission from J M Lobez and A Afzali 2013 Chem. Mater.25 3662. Copyright 2013 American Chemical Society.
Mentions: When the wrapping polymers act as the pigment, light-harvesting systems using the CNTs as an acceptor can be fabricated [242]. The unique charge transport features of the CNTs provide an efficient percolation network with a highly efficient exciton dissociation in polymeric bulk heterojunctions with the polymer acting as the donor and the CNT as the acceptor. Based on this concept, poly(3-alkylthiophenes) have been widely used [110, 239]. In 2005, poly(3-octylthiophene) (P3OT) was reported to wrap the SWCNTs and improved the photovoltaic behavior by the photo-induced electron transfer at the P3OT/SWCNT interfaces [243]. The combination of poly(3-alkylthiophenes) and s-SWCNTs forms a heterojunction with a type-II band alignment in which the HOMO and LUMO of the donor are higher than those of the acceptor (figure 23) [244]. This band structure leads to exciton dissociation at the interface with an ultrafast charge transfer from the P3HT to the s-SWCNTs [244–247], and the s-SWCNTs can act as efficient acceptors at the interface [244]. The time-resolved microwave conductivity measurements revealed that the photoexcitation of P3HT results in long-lived carriers due to the efficient spatial separation at the SWCNT–P3HT interface, which readily move electrons away to avoid recombination [248]. Another advantage is that organization of P3HT induced by SWCNTs [249] leads to the improvement of the exciton diffusion as well as the charge mobility in a P3HT/SWCNT composite [250]. It is important to note that the key progress in this field is the developments of the extraction technology of the s-SWCNTs, such as DGU [251] and PFO wrapping [88], since the contamination of m-SWCNTs in the active layer have a detrimental impact on the photocurrent [245], and theoretical studies have predicted that the band alignment of the P3HT/m-SWCNT is unfavorable for charge separation [244]. By utilizing s-SWCNTs, Dabera et al revealed the ground-state electron transfer from s-SWCNT to P3HT in the P3HT-wrapped s-SWCNTs, which facilitated the hole transportation property of the s-SWCNTs. The hybrid was used as hole transport layers for bulk heterojunction organic photovoltaics, and the device showed the highest power conversion efficiency (PCE = 7.6%) [252].

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.