“…This observation is comparable to the results of Backes et al who obtained more concentrated dispersions of SWNTs using SDS than with surfactants similar to 1 and 2. 7 The presence of one or two C6 linkers (compounds 3-6) does not have a significant effect on C MWNT under these conditions, nor does the choice of head group (i.e. G1 or G2).…”
Section: 39mentioning
confidence: 99%
“…1-pyrenebutyric acid or 1-pyrenebutanol). Pyrene derivatives offer both high binding affinity to CNTs 7,23,33,34,35 and synthetic versatility. Selected commercial surfactants⃰ ⃰ (structures in Figure 2) and "linker-free" surfactants (1 and 2 in Figure 1) with a head group bound directly to an anchor group were also investigated for comparison.…”
Section: Surfactant Design and Synthesismentioning
confidence: 99%
“…We have also investigated different hydrophilic head groups, as this has previously been shown to have an effect on CNT dispersing ability. 7 We have studied simple monocarboxylate head groups ("G0") and more complex moieties derived from first-and second-generation Newkome dendrons ("G1" and "G2" respectively). 31,32 We selected a different dendron to that used by Hirsch"s group, 7,21 as the presence of ether oxygen atoms in the dendron branches could further enhance the hydrophilicity and CNT dispersing ability of the surfactants.…”
Section: Surfactant Design and Synthesismentioning
confidence: 99%
“…5 One obstacle limiting the use of CNTs is the difficulty in processing these materials, 6 which generally form tightly packed bundles due to strong inter-tube π-π and van der Waals interactions. 7 This results in an extremely low solubility in all common solvents (in the absence of additional functionalisation). 8 A common method of overcoming these forces is the use of surfactants 9,10,11 and other dispersants (e.g.…”
Section: Introductionmentioning
confidence: 99%
“…Effective anchoring groups include polycyclic aromatic species such as anthracene, 22 pyrene, 7,23 perylene, 10,21,24,25 porphyrin derivatives 26 and more complex "nanotweezer" systems. 27,28 Suitable hydrophilic moieties include carboxylate, ammonium and sulfonate salts, 9 polyethylene glycol (PEG) derivatives 23 and Newkome 7,21,24,27 and glycerol 25 dendrons. Crown ethers and podands based on short ethylene glycol oligomers (OEGs) can also be effective hydrophilic moieties.…”
. (2015) 'Key role of the linker in pyrene-linker-carboxylate surfactants for the ecient aqueous dispersion of multiwalled carbon nanotubes.', RSC advances., 5 (115). pp. 95360-95368.Further information on publisher's website:http://dx.doi.org/10.1039/C5RA20250GPublisher's copyright statement:Additional information:
Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This study establishes that the structure of the linker group between the hydrophobic and hydrophilic units in the new surfactants 1-13 plays an important role in the dispersibility of multiwalled carbon nanotubes (MWNTs) in water. Systematic variation of the linker group in amphiphilic surfactants for carbon nanotubes has not been previously investigated. In the present series, the hydrophobic unit is derived from pyrene, the hydrophilic unit comprises 1-9 carboxylate groups and the linker is based on amide or ether moieties. The resulting MWNTsurfactant dispersions, up to concentrations and efficiencies of ca. 160 mg L -1 and almost 50%, respectively, have been characterised by UV-Vis absorption spectroscopy studies which provide detailed structure-property relationships, while transmission electron microscopy (TEM) was used to confirm that the MWNTs were well dispersed. For many of the new surfactants enhanced dispersion efficiency is observed compared to commercial surfactants. The efficiency of dispersion is affected by the presence, functionality and particularly the length of the linker, and also the number of terminal carboxylate units. The marked effect of sodium, potassium and calcium cations on the dispersion behaviour is explained by interactions between the metal ions and the surfactant and an ionic screening mechanism. We also demonstrate that the dispersibility of the MWNT-surfactant dispersions can be reversibly switched "off" and "on" by addition of acid and base, respectively. The experimental results are supported by theoretical calculations of solvation energy ΔE S . This study represents a significant advance in the design of multi-functional surfactants for efficient aqueous dispersion of carbon-based materials.
“…This observation is comparable to the results of Backes et al who obtained more concentrated dispersions of SWNTs using SDS than with surfactants similar to 1 and 2. 7 The presence of one or two C6 linkers (compounds 3-6) does not have a significant effect on C MWNT under these conditions, nor does the choice of head group (i.e. G1 or G2).…”
Section: 39mentioning
confidence: 99%
“…1-pyrenebutyric acid or 1-pyrenebutanol). Pyrene derivatives offer both high binding affinity to CNTs 7,23,33,34,35 and synthetic versatility. Selected commercial surfactants⃰ ⃰ (structures in Figure 2) and "linker-free" surfactants (1 and 2 in Figure 1) with a head group bound directly to an anchor group were also investigated for comparison.…”
Section: Surfactant Design and Synthesismentioning
confidence: 99%
“…We have also investigated different hydrophilic head groups, as this has previously been shown to have an effect on CNT dispersing ability. 7 We have studied simple monocarboxylate head groups ("G0") and more complex moieties derived from first-and second-generation Newkome dendrons ("G1" and "G2" respectively). 31,32 We selected a different dendron to that used by Hirsch"s group, 7,21 as the presence of ether oxygen atoms in the dendron branches could further enhance the hydrophilicity and CNT dispersing ability of the surfactants.…”
Section: Surfactant Design and Synthesismentioning
confidence: 99%
“…5 One obstacle limiting the use of CNTs is the difficulty in processing these materials, 6 which generally form tightly packed bundles due to strong inter-tube π-π and van der Waals interactions. 7 This results in an extremely low solubility in all common solvents (in the absence of additional functionalisation). 8 A common method of overcoming these forces is the use of surfactants 9,10,11 and other dispersants (e.g.…”
Section: Introductionmentioning
confidence: 99%
“…Effective anchoring groups include polycyclic aromatic species such as anthracene, 22 pyrene, 7,23 perylene, 10,21,24,25 porphyrin derivatives 26 and more complex "nanotweezer" systems. 27,28 Suitable hydrophilic moieties include carboxylate, ammonium and sulfonate salts, 9 polyethylene glycol (PEG) derivatives 23 and Newkome 7,21,24,27 and glycerol 25 dendrons. Crown ethers and podands based on short ethylene glycol oligomers (OEGs) can also be effective hydrophilic moieties.…”
. (2015) 'Key role of the linker in pyrene-linker-carboxylate surfactants for the ecient aqueous dispersion of multiwalled carbon nanotubes.', RSC advances., 5 (115). pp. 95360-95368.Further information on publisher's website:http://dx.doi.org/10.1039/C5RA20250GPublisher's copyright statement:Additional information:
Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. This study establishes that the structure of the linker group between the hydrophobic and hydrophilic units in the new surfactants 1-13 plays an important role in the dispersibility of multiwalled carbon nanotubes (MWNTs) in water. Systematic variation of the linker group in amphiphilic surfactants for carbon nanotubes has not been previously investigated. In the present series, the hydrophobic unit is derived from pyrene, the hydrophilic unit comprises 1-9 carboxylate groups and the linker is based on amide or ether moieties. The resulting MWNTsurfactant dispersions, up to concentrations and efficiencies of ca. 160 mg L -1 and almost 50%, respectively, have been characterised by UV-Vis absorption spectroscopy studies which provide detailed structure-property relationships, while transmission electron microscopy (TEM) was used to confirm that the MWNTs were well dispersed. For many of the new surfactants enhanced dispersion efficiency is observed compared to commercial surfactants. The efficiency of dispersion is affected by the presence, functionality and particularly the length of the linker, and also the number of terminal carboxylate units. The marked effect of sodium, potassium and calcium cations on the dispersion behaviour is explained by interactions between the metal ions and the surfactant and an ionic screening mechanism. We also demonstrate that the dispersibility of the MWNT-surfactant dispersions can be reversibly switched "off" and "on" by addition of acid and base, respectively. The experimental results are supported by theoretical calculations of solvation energy ΔE S . This study represents a significant advance in the design of multi-functional surfactants for efficient aqueous dispersion of carbon-based materials.
The insertion of organometallic molecules into the hollow core of singlewalled carbon nanotubes can drastically change their properties. Using biocompatible standardized suspensions of pristine, opened, and fi lled nanotubes, a very selective enhancement of the photoluminescence and optical absorption is observed. Via ferrocene encapsulation, the PL signal increases almost by a factor of three for tubes with chiralities such as (8,6) and (9,5). This behavior is attributed to a local electron charge transfer from the ferrocene molecules that balances out the p-type doping of the nanotubes resulting from the modifi ed charge distribution of the surfactant molecules and the opening process. The near infrared photoluminescence of the nanotubes in solution is strongly enhanced when ferrocene is encapsulated. The diameter-dependent charge transfer is additionally confi rmed by fi rst principles calculations. These fi ndings highlight an essential ingredient to optimize the application of solvated nanotubes, for instance, as in-vivo near infrared sensors in biomedical research.
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