New basic insight into reductive functionalization sequences of single walled carbon nanotubes (SWCNTs)
Ferdinand Hof1, Sebastian Bosch, Siegfried Eigler
1Department of Chemistry and Pharmacy & Institute of Advanced Materials and Processes (ZMP), Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) , Henkestrasse 42, 91054 Erlangen, Germany.
Journal of the American Chemical Society
|November 22, 2013
Summary
Reduced single-walled carbon nanotubes (SWCNTs) undergo incomplete alkylation, reacting further with moisture to form mixed functionalized derivatives. This reactivity is influenced by the K:C ratio and the electrophile
Area of Science:
- Materials Science
- Nanotechnology
- Chemistry
Background:
- Reduced single-walled carbon nanotubes (SWCNTs) are susceptible to various chemical modifications.
- Understanding their reactivity is crucial for controlled functionalization.
Purpose of the Study:
- To investigate the reactivity of reduced SWCNTs (carbon nanotubides) towards covalent functionalization with hexyl iodide.
- To explore the impact of ambient conditions (air, moisture) on functionalized SWCNTs.
- To elucidate the reaction mechanism and identify resulting functional groups.
Main Methods:
- Systematic spectroscopic analysis including Raman, absorption, fluorescence, and IR spectroscopy.
- Thermogravimetric analysis coupled with mass spectrometry (TG/MS).
- Postfunctionalization reactions and control experiments with potassium superoxide (KO2).
Main Results:
- Alkylation with hexyl iodide does not fully discharge the SWCNTs, allowing subsequent reactions with moisture.
- Mixed functionalized SWCNT derivatives containing H- and OH-addends are formed, alongside hexyl groups.
- The degree of hexylation correlates with the K:C ratio of the starting material.
- OH-groups are confirmed via postfunctionalization and control experiments.
Conclusions:
- A plausible reaction mechanism for SWCNT side wall functionalization is proposed.
- The extent of side reactions is influenced by the reduction potential of electrophiles and reoxidation processes.
- Incomplete quenching of negative charges in SWCNTs leads to follow-up reactions with oxidants like O2.
