Adverse Effect of PTFE Stir Bars on the Covalent Functionalization of Carbon and Boron Nitride Nanotubes Using Billups–Birch Reduction Conditions

Abstract

The functionalization of nanomaterials has long been studied as a way to manipulate and tailor their properties to a desired application. Of the various methods available, the Billups–Birch reduction has become an important and widely used reaction for the functionalization of carbon nanotubes (CNTs) and, more recently, boron nitride nanotubes. However, an easily overlooked source of error when using highly reductive conditions is the utilization of poly(tetrafluoroethylene) (PTFE) stir bars. In this work, we studied the effects of using this kind of stir bar versus using a glass stir bar by measuring the resulting degree of functionalization with 1-bromododecane. Thermogravimetric analysis studies alone could deceive one into thinking that reactions stirred with PTFE stir bars are highly functionalized; however, the utilization of spectroscopic techniques, such as Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, tells otherwise. Furthermore, in the case of CNTs, we determined that using Raman spectroscopy alone for analysis is not sufficient to demonstrate successful chemical modification.

Real-Time Visualization and Dynamics of Boron Nitride Nanotubes Undergoing Brownian Motion

“…Because imaging in the UV range is challenging, fluorescence imaging from direct excitation has not been reported, and an external fluorescent tag must be used. Additionally, since BNNTs are amphiphobic, covalent functionalization or the use of a dispersing agent must be utilized to obtain BNNT dispersions. − ,− To our knowledge, very little work has been done toward real-time BNNT visualization in solution. ,,, Recent work in our group has shown that BNNTs can be individualized in solution using cationic surfactants . With this in mind, we synthesized a line of cationic surfactants that have a fluorescent molecule (rhodamine B) included in the structure and showed that it could be used to individualize and image CNTs and BNNTs .…”

Tunable Alkylation of White Graphene (Hexagonal Boron Nitride) Using Reductive Conditions

“…It is noticeable that samples exposed to the Billups−Birch reaction conditions seem to experience slight shifts in the B−N stretching energy that may be due to lattice deformation 38 and that has been previously observed upon functionalizing BNNTs. 50,51 The inset in Figure 2a shows an enlargement of the C−H st region, and it is qualitatively discernible that the intensity of these peaks increases from 1:5 to 1:20 and then decreases in 1:40 and even more in 1:60. We further analyzed the infrared spectra by obtaining the ratio between the intensities of the most intense peak of CH st vibrations (2920 cm −1 ) and the B−N st (Figure 2b).…”

“…Although this method has been used extensively for carbon, it has only recently found application in boron nitride functionalization. Our research group functionalized multiwalled boron nitride nanotubes with dodecyl chains using lithium, liquid ammonia, and 1-bromododecane as reagents. , …”

Sodium Naphthalenide Diglyme Solution for Etching PTFE, Characterizations and Molecular Modelization

“…The solution is difficult to store and handle at commercial scale because of its boiling point around À 40 °C. [9] In the late 1950s, glycol diethers (or glymes) appeared and helped to replace both liquid ammonia and THF as a solvent for sodium complexed with naphthalene (naphthalenide) in most in-house etching operations. About thirty years later, studies have emerged where THF is replaced by a glyme showing their effectiveness using a diglyme-sodium naphthalenide etchant, for instance.…”