Park M, Hwang S, Ju SY. 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.
NANOMATERIALS (BASEL, SWITZERLAND) 2022;
12:3380. [PMID:
36234506 PMCID:
PMC9565467 DOI:
10.3390/nano12193380]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Revised: 09/17/2022] [Accepted: 09/23/2022] [Indexed: 06/16/2023]
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 (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.
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