Pillar[5]arene-Decorated Single-Walled Carbon Nanotubes

Abstract

Control of single-walled carbon nanotube dispersion properties is of substantial interest to the scientific community. In this work, we sought to investigate the effect of a macrocycle, pillar[5]arene, on the dispersion properties of a polymer–nanotube complex. Pillar[5]arenes are a class of electron-rich macrocyclic hosts capable of forming inclusion complexes with electron-poor guests, such as alkyl nitriles. A hydroxyl-functionalized pillar[5]arene derivative was coupled to the alkyl bromide side chains of a polyfluorene, which was then used to coat the surface of single-walled carbon nanotubes. Noncovalent functionalization of carbon nanotubes with the macrocycle-containing conjugated polymer significantly enhanced nanotube solubility, resulting in dark and concentrated nanotube dispersions (600 μg mL –1 ), as evidenced by UV–vis–NIR spectroscopy and thermogravimetric analysis. Differentiation of semiconducting and metallic single-walled carbon nanotube species was analyzed by a combination of UV–vis–NIR, Raman, and fluorescence spectroscopy. Raman spectroscopy confirmed that the concentrated nanotube dispersion produced by the macrocycle-containing polymer was due to well-exfoliated nanotubes, rather than bundle formation. The polymer–nanotube dispersion was investigated using 1 H NMR spectroscopy, and it was found that host–guest chemistry between pillar[5]arene and 1,6-dicyanohexane occurred in the presence of the polymer–nanotube complex. Utilizing the host–guest capability of pillar[5]arene, the polymer–nanotube complex was incorporated into a supramolecular organogel.

Reactive, Aqueous-Dispersible Polyfluorene-Wrapped Carbon Nanotubes Modulated with an Acidochromic Switch via Azide–Alkyne Cycloaddition

“…Our research group has been probing a simple tactic to concurrently decorate single-walled carbon nanotubes (SWNTs) and avoid damage to nanotube properties. − Substantial efforts have been made to utilize the exceptional optoelectronic, − structural, − and mechanical − properties of SWNTs. However, as-produced SWNT samples are typically insoluble in organic and aqueous solvents due to SWNT bundling .…”

Visible Light-Mediated Photoclick Functionalization of a Conjugated Polymer Backbone

“…This structural diversity, in tandem with postpolymerization modifications such as doping, enables the tailoring of polymer physical and optoelectronic properties, including solubility, absorption, and emission wavelengths, and bandgap (alongside highest occupied molecular orbital/lowest unoccupied molecular orbital energies). − Research into the structural diversity of the conjugated polymers has flourished in the field of organic electronics, with applications including field-effect transistors, organic photovoltaics, , light-emitting diodes (LEDs), − chemical sensors, and magneto-optic materials. − Recent advances include conjugated polymers containing radicals in both the side chains , and backbone, the latter of which exhibits ambipolar redox activity and the Faraday effect. Beyond this, conjugated polymers have also been employed as dispersion agents to sort single-walled carbon nanotube (SWNT) species, − as functional SWNT coatings, − or as scaffolds for thiol–ene click chemistry via side chain functionalization . In exploring various conjugated polymer structures, synthetic control over polymer attributes such as the degree of polymerization (DP) and dispersity ( D̵ ) is imperative, as these factors influence polymer properties.…”

Preparation and Characterization of Cationic Water-Soluble Pillar[5]arene-Modified Zeolite for Adsorption of Methyl Orange

“…It has a tubular morphology compared with other macrocyclic molecules such as crown ether, cyclodextrin, − calixarene, , and cucurbituril . Pillararenes have been widely used in gas adsorption, , wastewater treatment, − drug transport, − and molecular recognition − due to their easy modification, simplicity of preparation, and optimal performance. , …”