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Sorting single‐walled carbon nanotubes (SWNTs) that are heterogeneous into homogeneous groups based on their electronic type, chirality, and handedness is crucial for optoelectronic and biological applications. To achieve this, researchers have utilized dispersants with different binding affinities to sort SWNTs according to their chiralities. This review article provides an overview of the methods developed for sorting SWNTs using dispersants, with a particular focus on the role played by dispersant binding affinities. The article is organized into six sections, including an introduction, a background on SWNTs and dispersant‐based individualization of SWNTs, information on dispersants and their binding affinities, separation methods for SWNTs based on controlling the dispersant binding affinity, parameters used to control dispersant binding affinity, and a conclusion. It is hoped that this review will enhance understanding of the intricate interactions between dispersants and SWNTs, leading to the development of new SWNT sorting methods for future applications. [ABSTRACT FROM AUTHOR]

Flavin with defined helical self-assembly helps to understand chemical designs for obtaining high-purity semiconducting (s)-single-walled carbon nanotubes (SWNT) in a diameter (dt)-selective manner for high-end applications. In this study, flavins containing 8, 12, 16, and 20 n-alkyl chains were synthesized, and their single/tandem effects on dt-selective s-SWNT dispersibility were investigated at isomolarity. Flavins with n-dodecyl and longer chain lengths (FC12, FC16, and FC20) act as good surfactants for stable SWNT dispersions whereas n-octyl flavin (FC8) exhibits poor dispersibility owing to the lack of SWNT buoyancy. When used with small-dt SWNT, FC8 displays chirality-selective SWNT dispersion. This behavior, along with various flavin helical motifs, prompts the development of criteria for 'side chain length (lS)' required for stable and dt-selective SWNT dispersion, which also explains lS-dependent dt-enrichment behavior. Moreover, SWNT dispersions with flavins with dodecyl and longer lS exhibit increased metallic (m)-SWNT, background absorption-contributing carbonaceous impurities (CIs) and preferential selectivity of s-SWNT with slightly larger dt. The increased CIs that affect the SWNT quantum yield were attributed to a solubility parameter. Furthermore, the effects of flavin lS, sonication bath temperature, centrifugal speed, and surfactant concentration on SWNT purity and s-/m-SWNT ratio were investigated. A tandem FC8/FC12 provides fine-tuning of dt-selective SWNT dispersion, wherein the FC8 ratio governs the tendency towards smaller dt. Kinetic and thermodynamic assemblies of tandem flavins result in different sorting behaviors in which wide dt-tunability was demonstrated using kinetic assembly. This study highlights the importance of appropriate side chain length and other extrinsic parameters to obtain dt-selective or high-purity s-SWNT. [ABSTRACT FROM AUTHOR]

Although successfully implemented for optoelectronic devices of two‐dimensional materials, deterministic transfer for thin single‐walled carbon nanotube (SWNT) film has not been realized. Herein, we report a transfer method of few hundreds nanometer‐thick SWNT film to a desired prepatterned substrate position with few micrometer precision. This method comprises poly(methyl methacrylate) (PMMA)‐coated SWNT film, creating surface anisotropy on both sides for SWNT film transfer, and two sets of translators manipulating the film to desired position and angle. Especially, adsorption and desorption of PMMA‐coated SWNT film by each translator were modulated by use of interfacial water which not only promotes PMMA side to the transient sample loader via water capillary and releases the final substrate with capillary assisted sliding. Successful transfer of thin SWNT film with few tens of micrometer precision was achieved and will be beneficial for the preparation of high‐end optoelectronic devices. [ABSTRACT FROM AUTHOR]

We fabricated multiple-layered nonwoven multiwalled carbon nanotubes (MWCNT) sheets by means of treating MWCNTs with a spark plasma sintering process. We characterized the samples by Raman spectroscopy, X-ray diffraction (XRD), scanning electron microscopy, transmission electron microscopy, and the field effect mobility method. Each thin nonwoven MWCNT layer is mainly comprised of interlocked, intertwined, or interconnected MWCNTs. XRD and Raman spectra coincidentally revealed that the graphitization occurred in the course of transformation from pristine to nonwoven MWCNTs. The multiple-layered nonwoven MWCNTs showed a higher electrical conductance than a single-layered nonwoven MWCNTs sheet. [ABSTRACT FROM AUTHOR]

Binding affinity and thermodynamicunderstanding between a surfactantand carbon nanotube is essential to develop various carbon nanotubeapplications. Flavin mononucleotide-wrapped carbon nanotubes showinga large redshift in optical signature were utilized to determine thebinding affinity and related thermodynamic parameters of 12 differentnanotube chiralities upon exchange with other surfactants. Determinedfrom the midpoint of sigmoidal transition, the equilibrium constant(K), which is inversely proportional to the bindingaffinity of the initial surfactant-carbon nanotube, provided quantitativebinding strengths of surfactants as SDBS > SC ≈ FMN >SDS,irrespective of electronic types of SWNTs. Binding affinity of metallictubes is weaker than that of semiconducting tubes. The complex Kpatterns from semiconducting tubes show preference tocertain SWNT chiralities and surfactant-specific cooperativity accordingto nanotube chirality. Controlling temperature was effective to modulate Kvalues by 30% and enables us to probe thermodynamic parameters.Equally signed enthalpy and entropy changes produce Gibbs energy changeswith a magnitude of a few kJ/mol. A greater negative Gibbs energyupon exchange of surfactant produces an enhanced nanotube photoluminescence,implying the importance of understanding thermodynamics for designingnanotube separation and supramolecular assembly of surfactant. [ABSTRACT FROM AUTHOR]

We report a novel on-chip Rayleigh imaging technique using wide-field laser illumination to measure optical scattering from individual single-walled carbon nanotubes (SWNTs) on a solid substrate with high spatial and spectral resolution. This method in conjunction with calibrated AFM measurements accurately measures the resonance energies and diameters for a large number of SWNTs in parallel. We apply this technique for fast mapping of key SWNT parameters, including the electronic-types and chiral indices for individual SWNTs, position and frequency of chirality-changing events, and intertube interactions in both bundled and distant SWNTs. [ABSTRACT FROM AUTHOR]

Although solvent governed stability, selection and optical behavior of single walled carbon nanotubes (SWNTs) brought about by using specialized surfactants have importance in relation to various optoelectronic and biological applications, their origins and solvatochromism have not been thoroughly explored owing to the lack of ideal surfactant dispersing SWNTs. We show that solvent driven SWNT selection and solvatochromism occurs in SWNTs wrapped by two flavin derivatives in solvents with dielectric constants (ε) ranging from 2.3 to 80.4. Flavin-SWNT nanocomposite dispersions exhibit near-armchair and chirality-specific enrichment in lower ε aromatic solvents, and those with broader chirality selectivity are formed in higher ε solvents. Those trends are also observed by controlling flavin concentration. Consideration of optical spectra provides relative quantum yields of flavin-SWNT in each solvent, showing toluene and p -xylene dispersions as best owing to highly individualized SWNT. The selectivities and relative stabilities of the flavin-SWNT nanoconjugates are associated with the solubility parameter (δ), which controls the respective morphology of the side chains and the relative Gibbs energies of the nanoconjugates relative to those of the free flavin and SWNTs. Differences between δ of side chains vs. the media results in extended and collapsed side chain conformations in respective lower and higher ε solvents, leading to diameters (d t) selection of SWNT owing to diameter modulation of the isoalloxazine assembly. In addition, with increasing ε optical transitions of flavin/SWNT exhibit lower bathochromic shifts owing to a passivating role played by the isoalloxazine that does not take place with other surfactants. The results suggest new guidelines for the design of good SWNT dispersions that take into consideration self-association of the surfactant, conformations of side chains and the nature of the solvent. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract High-end applications of single-walled carbon nanotube (SWNT) require detailed understanding of their binding affinity (K d) with surfactants. Here, we quantitatively determined the comprehensive K d and aggregation number (γ) of nine nonionic and anionic surfactants according to SWNT chirality. Photoluminescence (PL)-based titration using flavin mononucleotide (FMN)-SWNT complexes showing the largest redshifted optical transition enabled quantitative comparison of the surfactants and displayed distinct first and second regimes which correspond to partial and full replacements of FMN, respectively. Especially, the second transition exhibited sigmoidal PL change whose middle point denoted by the inverse of K d slightly differs from critical micelle concentration of surfactant alone, depending on its functional groups. Moreover, nonionic surfactants displayed larger K d and lower γ values than the anionic did. Specifically, K d values between Pluronic F108 and sodium dodecyl sulfonate differ by four orders of magnitude. Such differences were rationalized in terms of the occupied volume of the micelle based on the hydrodynamic volume and γ. During the replacement, K d and γ were affected by the degree of surfactant rearrangement induced by aging process, leading to more stable complex. Scaling the interactions between surfactant and SWNT provides useful guidelines to design novel SWNT sorting method using more than two surfactants. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

[Display omitted] • The synthesized POBE-BzE has capability to disperse SWNT in water and p -xylene. • POBE-BzE/SWNT can be extracted to p -xylene from water in diameter selective manner. • Partition coefficients are obtained to explain those diameter selective extractions. Aqueous two-phase extraction is instrumental for obtaining single-walled carbon nanotubes (SWNT) with uniform physical properties. This study reports that a nonionic amphiphilic poly(2-ethyloxazoline)-benzyl ether derivative (POBE-BzE) not only efficiently disperses SWNT in both water and p -xylene, but can also be utilized as a single-surfactant for partitioning SWNT in a water/ p -xylene two-phase extraction in a diameter (d t) selective manner. While individual POBE-BzE/SWNT dispersions exhibit similar photoluminescence positions from the SWNT, d t -dependency occurs according to the solvent. Upon two-phase extraction, a d t SWNT >0.9 nm was mainly extracted to the p -xylene layer, and its partition coefficient was investigated by varying the phase transfer catalyst or sodium chloride amounts, where sodium chloride served as a better transfer agent. The d t selective behavior and its partition coefficient were rationalized by the tight and loose configurations of the BzE moiety in each medium. This novel amphiphilic polymeric surfactant and two-phase extraction may be useful for sorting SWNT and other nanomaterials according to their size. [ABSTRACT FROM AUTHOR]