Noncovalent Functionalization as an Alternative to Oxidative Acid Treatment of Single Wall Carbon Nanotubes with Applications for Polymer Composites

Abstract

We have created stable dispersions of single wall carbon nanotubes (SWNTs) in water by employing a noncovalent functionalization scheme that allows carboxylic acid moieties to be attached to the SWNT surface by a pi-pi stacking interaction. Pyrenecarboxylic acid (PCA) is noncovalently attached to the surface of SWNTs and affords highly uniform and stable aqueous dispersions. This method was developed to provide a noncovalent alternative to the commonly used oxidative acid treatment functionalization of carbon nanotubes. This alternative strategy avoids the damage to the carbon nanotube structure inherent to oxidative acid treatments. Carbon nanotubes are commonly functionalized with oxidative acid treatment schemes to create polymer-nanotube composites and improve the adhesion between the polymer and carbon nanotubes. Composites of SWNTs and polycarbonate were prepared and tested to determine the effect of PCA on the adhesion of the SWNTs to the polymer matrix. These tests confirmed that PCA improved the SWNT-polycarbonate adhesion and improved the dispersion of the SWNTs throughout the matrix. This study demonstrates that stable dispersions of SWNTs can be achieved without substantial cutting, introduction of defects, or covalent modification, by employing a simple and effective noncovalent functionalization with PCA.

New strategies for the chemical characterization of multi-walled carbon nanotubes and their derivatives

“…Amine functionalized MWCNTs (MWCNT-NH 2 ) were prepared using a diazotation reaction developed by FutureCarbon GmbH. The grafting of styrene from the MWCNT surface was done following a procedure described elsewhere [35], with a final polystyrene content of 15wt% (PS 15 The disks prepared for the Raman measurement were prepared by pressing 100 mg of the CNT sample at 5 or 10 t (Ø 1.3 cm) for 5 to 15 min.…”

“…[7,8] It has been reported in several cases that the modification of the surface of the carbon nanotubes with functional groups can help to disperse them, and may lead to enhancement of mechanical properties and electrical conductivity in different matrices. [9][10][11][12][13][14][15][16][17][18][19][20][21] In the case of the preparation of polymer nanocomposites based on carbon nanotubes, various researchers have reported an improvement of the mechanical properties when covalently surfacemodified carbon nanotubes were used. Compared with non-covalently functionalized CNTs, covalently functionalized ones can interact directly with the matrix system as the polymer bound to the CNT can transfer stress directly from the matrix to the CNT structure.…”

A review on the role of interface in mechanical, thermal, and electrical properties of polymer composites

“…Noncovalent functionalization has been used for dispersion of fillers (i.e., CNTs [273,274] and graphene [171,275]) in polymer matrix. This type of functionalization enhances the dispersion quality of fillers.…”

The effect of different chemical treatments on the structure and stability of aqueous dispersion of iron- and iron oxide-filled multi-walled carbon nanotubes

“…In this paper, we describe the effect of five different chemical treatments on the composition, structure and aqueous dispersibility of the iron-and iron oxide-filled MWCNT sample. Although several articles have been recently published focusing on the different chemical treatment of CNTs, [3][4][5]31 there are no systematic data on the effect of these chemical treatment methods on metal-filled CNT samples. …”