1. The Effects of Lengths of Flavin Surfactant N -10-Alkyl Side Chains on Promoting Dispersion of a High-Purity and Diameter-Selective Single-Walled Nanotube.
- Author
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Park, Minsuk, Hwang, Seongjoo, and Ju, Sang-Yong
- Subjects
SURFACE active agents ,DISPERSION (Chemistry) ,FLAVINS ,CARBON nanotubes ,SONICATION ,BUOYANCY - Abstract
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 (d
t )-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]- Published
- 2022
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