Abstract
Different reactions have been reported for the successful functionalization of carbon nanotubes (CNT). The Diels-Alder cycloaddition is recognized as a plausible chemical approach, but few reports are known where this strategy has been used. In this study, the functionalization was performed by 1,3-butadiene generated from 3-sulfolene under heating conditions in diglyme. This simple and easily scalable method resulted in functionalized CNT with mass losses of 10–23% by thermogravimetric analysis (nitrogen atmosphere). The functionalization was also supported by acid-base titration, elemental analysis, temperature programmed desorption and X-ray photoelectron spectroscopy. The high content in oxygen detected on the CNT surface was assigned to anhydride formation due to a cascade oxidation of the alkene groups generated in the cycloaddition reaction. The complete evolution of the alkene leads to a grafting density of 4.2 mmol g−1 for the anhydride moiety. Ab-initio calculations in CNT model systems indicate that the Diels-Alder addition of butadiene is a feasible process and that subsequent oxidation reactions may result in the formation of the anhydride moiety. The presence of the anhydride group is a valuable asset for grafting a multitude of complex molecules, namely through the nucleophilic addition of amines.
Highlights
Carbon nanotubes (CNT) continue to attract great interest from the scientific community as a result of their unique electrical, mechanical and thermal properties
We demonstrate that the functionalization of MWCNT with 1,3-butadiene generated from 3-sulfolene takes place and we provide theoretical calculations that indicate that the cycloaddition of 1,3butadiene to model CNT is mildly exothermic and possible
The characterization of functionalized material by thermogravimetric analysis (TGA), potentiometric titration, X-ray photoelectron spectroscopy (XPS), temperature programmed desorption (TPD) and elemental analysis shows that the CNT are decorated with carboxylic anhydride groups
Summary
Carbon nanotubes (CNT) continue to attract great interest from the scientific community as a result of their unique electrical, mechanical and thermal properties. Some theoretical studies on the DielsAlder cycloaddition of butadiene to single wall carbon nanotubes (SWCNT) suggested that this reaction was not feasible, the same authors concluded in a subsequent study that the [4+2] cycloaddition of o-quinodimethane was a plausible process [7]. This was experimentally proved for the first time in 2004 by Delgado et al [8], when SWCNTs were reacted with o-quinodimethane generated from an appropriate sultine. Under the preparation conditions reported, the original alkene undergoes a cascade oxidation process, to yield carboxylic anhydride groups
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
