Effect of Single‐walled Carbon Nanotube (SWCNT) Composition on Polyfluorene‐Based SWCNT Dispersion Selectivity

Abstract

Applications of single-walled carbon nanotubes (SWCNTs) are hampered by the mixtures of metallic and semiconducting SWCNTs that are present in commercial samples. Separation of SWCNTs according to electronic type is therefore extremely important. Recently, the selective interaction between the conjugated polymer, poly(9,9-di-n-dodecyl-fluorenyl-2,7-diyl) and semiconducting SWCNTs has been reported. However, the mechanism responsible for this selectivity is poorly understood. To determine whether this polymer is only selective for semiconducting SWCNTs, we exposed it to mixtures of metallic and semiconducting SWCNTs in different ratios. We found that the polymer is indeed selective for semiconducting SWCNTs in toluene, but only when the starting ratio is below 67:33 metallic:semiconducting. When the starting ratio is increased to 67:33 or higher, the amount of metallic SWCNTs dispersed dramatically increases. If the solvent is changed to THF, the threshold ratio at which metallic SWCNTs begin to be dispersed is much lower. This indicates that the polymer exhibits a preference for interaction with semiconducting SWCNTs, but is not precluded from interaction with metallic SWCNTs if exposed to a high enough concentration.

Chirality enriched carbon nanotubes with tunable wrapping via corona phase exchange purification (CPEP)

“…37,38 This step relies also on the raw nanotube material and its ratio of semiconducting to metallic nanotubes and the containing chiralities. 70 Therefore, by choosing the appropriate SWCNT material and PFO-polymer for dispersion, CPEP can grant access to a brought range of enriched SWCNTs with desired surface modifications. This approach can be especially relevant for fundamental studies and applications of SWCNTs that require sophisticated surface chemistry beyond standard surfactants.…”

Dispersion of arc-discharged single-walled carbon nanotubes using the natural α-amino acid derivative N-dodecanoyl leucinate

“…In 633 nm excitation spectrum, the bands between 160 to 210 cm À1 range are ascribed to metallic SWNTs, and the strong peak at 170 cm À1 and the shoulder at 184 cm À1 observed in Fig. 4a could be assigned to the metallic carbon nanotube with indices of (14,5) and (15,3). Whereas, the bands between 125 to 160 cm À1 range are due to semiconducting SWNTs, and the moderate peak at 158 cm À1 could be assigned to the semiconducting carbon nanotube with index of (14,7).…”

“…The applied dispersants include conjugated polymers, biomolecules, ionic liquids and various surfactants. [13][14][15][16] Aer noncovalent individualization, SWNTs were sorted by diameter, electronic type, chirality and even handedness to some extent via ultracentrifugation, 17 aqueous two-phase extraction 18,19 and gel chromatography. 20,21 Among the dispersants applied, biomolecules are crucial to the medical and diagnostic applications of SWNTs as drug carriers, 8,22 therapeutic agents 23 or ultrasensitive biosensors in cellular systems.…”

Semiconducting Single‐Walled Carbon Nanotubes or Very Rigid Conjugated Polymers: A Comparison

“…[65] For long-term stable dispersions of carbon nanotubes in water or common organic solvents the tools of colloidal chemistry are used, that is, surfactants and dispersants. [77] Under www.advelectronicmat.de ideal conditions predominantly semiconducting and even monochiral nanotube samples can be produced. [69] The creation of nanotube dispersions with high quality (i.e., individualized nanotubes with a controlled surfactant shell, absence of bundles) also enabled the separation of metallic and semiconducting and even single chiralities based on different buoyant densities (density gradient ultracentrifugation, DGU), [70] different binding affinities to the fibers of gel columns (sizeexclusion gel-chromatography), [71] or slightly different chemical potentials (aqueous two-phase separation).…”

“…The dispersion of SWCNTs with suitable π‐conjugated polymers offers the advantage of separation and colloidal stabilization in a single step through selective polymer wrapping . Here the π–π interactions between the nanotube and the conjugated polymer provide a measure of selectivity that also depends on alkyl side chain length, molecular weight of the polymer, temperature, and starting material . Under ideal conditions predominantly semiconducting and even monochiral nanotube samples can be produced …”