Gel Chromatography for Separation of Single-Walled Carbon Nanotubes

Abstract

Carbon nanotubes (CNTs), having either metallic or semiconducting properties depending on their chirality, are advanced materials that can be used for different devices and materials (e.g., fuel cells, transistors, solar cells, reinforced materials, and medical materials) due to their excellent electrical conductivity, mechanical strength, and thermal conductivity. Single-walled CNTs (SWNTs) have received special attention due to their outstanding electrical and optical properties; however, the inability to selectively synthesize specific types of CNTs has been a major obstacle for their commercialization. Therefore, researchers have studied different methods for the separation of SWNTs based on their electrical and optical properties. Gel chromatography methods enable the large-scale separation of metallic/semiconducting (m/s) SWNTs and single-chirality SWNTs with specific bandgaps. The core principle of gel chromatography-based SWNT separation is the interaction between the SWNTs and gels, which depends on the unique electrical properties of the former. Controlled pore glass, silica gel, agarose-based gel, and allyl dextran-based gel have been exploited as mediums for gel chromatography. In this paper, the interaction between SWNTs and gels and the different gel chromatography-based SWNT separation technologies are introduced. This paper can serve as a reference for researchers who plan to separate SWNTs with gel chromatography.

Understanding the partitioning behavior of single-walled carbon nanotubes using an aqueous two-phase extraction system composed of non-ionic surfactants and polymers

“…As soon as a minimal amount of 2% SDS was added (50 mL), the peak representing the (6,5) chirality in the top phase suddenly decreased in intensity. Simultaneously, (7,5) SWCNTs became the majority type of SWCNTs in the top phase in the explored wavelength range. Noticeably, as the volume of SDS increased to 400 mL, the peak attributed to (6,5) SWCNTs (d = 0.757 nm) was further reduced and disappeared at higher concentrations, which led to the isolation of larger diameter species such as (7,5) SWCNTs (d = 0.829 nm) in this phase.…”

“…Simultaneously, (7,5) SWCNTs became the majority type of SWCNTs in the top phase in the explored wavelength range. Noticeably, as the volume of SDS increased to 400 mL, the peak attributed to (6,5) SWCNTs (d = 0.757 nm) was further reduced and disappeared at higher concentrations, which led to the isolation of larger diameter species such as (7,5) SWCNTs (d = 0.829 nm) in this phase. Unfortunately, a further increase in the SDS amount led to the disappearance of phase separation in the sample due to excessive dilution of the system, which moved the operating point to the single-phase area.…”

“…Numerous studies have been conducted to achieve structural homogeneity 4 via selective synthesis 5 and post-synthesis separation techniques. 6 Among the most popular SWCNT purification techniques, such as chromatography, 7 ultracentrifugation, 8 electrophoresis, 9 selective solubilization, 10 etc., the aqueous twophase extraction (ATPE) method exhibits exceptional efficiency, so it is frequently employed to enrich materials with the targeted type of SWCNTs. [11][12][13][14] In general, in the case of SWCNT separation, three types of biphasic systems have been reported: poly(ethylene glycol)/ dextran, poly(ethylene glycol)/polyacrylamide, and polyvinylpyrrolidone/dextran.…”

Single-chirality of single-walled carbon nanotubes (SWCNTs) through chromatography and its potential biological applications

“…Gel columns also have advantages such as suitability, simplicity, and straightforward process. 109,110 ATPE has been used to separate animal and plant cells, bacteria, viruses, and cellular organelles, such as chloroplasts, mitochondria, membrane vesicles, proteins, and nucleic acids. ATPE is made by adding two chemically different water-soluble polymers or polyethylene glycol and salt to water, forming two immiscible phases.…”

“…Gel columns also have advantages such as suitability, simplicity, and straightforward process. 109,110…”