Sidewall Covalent Functionalization of Single Wall Carbon Nanotubes Through Reactions of Fluoronanotubes with Urea, Guanidine, and Thiourea

Abstract

Sidewall covalent functionalization of carbon nanotubes is necessary to achieve smaller bundles and individuals, link to other functional moieties, and aid in better dispersion in composites. In the present study, we developed a one-step functionalization method which uses fluorinated single wall carbon nanotubes (F-SWNTs) as starting materials in the reactions with urea, thiourea, or guanidine. Through these reactions, the derivatives with terminal amide and heteroamide groups on the nanotube sidewalls have been prepared. The nanotubes also contain some residual fluorine generating bifunctional derivatives. These derivatives were characterized by Raman spectroscopy, Fourier Transform infrared (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM). Compared to fluorinated nanotubes, the urea-functionalized SWNTs (U-F-SWNTs) have shown among the three derivatives the highest stability of their dispersions in DMF, water, and aqueous urea solutions, thereby creating new opportunities for biomedical applications with nanotubes. These bifunctional derivatives show improved dispersion in the epoxy system that should aid in creating an interface between the SWNTs and the polymers and result in much stronger composites. The three derivatives are efficiently synthesized, and the method can be easily scaled up for applications such as creating an integrated polymer network for stronger composites, coatings, and for use in biomedical applications and nanoelectronic devices.

Enhancing lithium–sulphur battery performance by strongly binding the discharge products on amino-functionalized reduced graphene oxide

“…The absorption peaks at 3,000-3,600 cm À 1 correspond to the O-H stretching vibrations of hydroxyl groups on GO surface and adsorbed water molecules. After reacting with EDA, the intensity of these peaks is greatly suppressed, while new peaks arise at 1,564, 1,150-1,465 and 3,430 cm À 1 that can be assigned to the antisymmetric C-N stretching vibrations coupled with out-of-plane NH 2 and NH modes, as well as the N-H stretching vibrations 22,34,35 . The scissoring in-plane bending mode of primary -NH 2 groups is also observed at 1,633 cm À 1 by overlapping with the peaks from C-C aromatic ring modes at 1,615 cm À 1 (ref.…”

Functional Covalent Chemistry of Carbon Nanotube Surfaces

“…Specifically, many of these approaches take advantage of the use of carboxylic acid residues immobilized onto SWNTs; in this regard, a recent paper proposed either a direct coupling of ethylenediamine with carboxylic acid groups or reduction of carboxyl groups to hydroxymethyl moieties followed by a subsequent transformation into aminomethyl groups as a means of creating amino-functionalized nanotubes for binding to (i) polymers and (ii) biological systems. [183] It is notable that one can also envision creation of these versatile amide and heteroamide functionalities on nanotube sidewalls using either fluorinated or iodinated SWNTs as a precursor [184,185] and subsequently using these entities as building blocks in copolymerization and polycondensation reactions to create useful nanocomposite structures with enhanced physical properties.…”

Carbon Nanotubes Anchored to Silicon for Device Fabrication

“…Fluorination of CNTs, to produce F-CNTs, has yielded highly useful products that can be used directly for surface attachment or as precursors for production of other functionalities such as hydroxyl groups. [37][38][39] Typically, fluorination is achieved by placing the CNTs in elemental fluorine or F 2 gas and HF at high temperatures. [40] Fluorine gas generally results in high reaction rates and deep penetration into the CNTs, although precise control of the depth and side-wall functionalization is limited.…”