Reproducibility and efficiency of carbon nanotube end-group generation and functionalization

• In a systematic fashion, several methods for esterification and  amidation of single-walled carbon nanotubes have been evaluated with   focus on efficiency and reproducibility in forming covalently   functionalized products soluble in organic media. The outcome of   transformations was determined using IR, Raman and NMR spectroscopy and   by thermogravimetric analysis (TGA). Amidation proceeding via a   SWNT-(COCl)(n) intermediate yielded the expected covalent product,  whereas carboxylate salt formation dominated with other attempted   methods. Esterification was achieved via the acyl chloride method and   via alkylation of SWNT-(COO-)(n), the latter being the more efficient   method. A non-covalent solubilizing interaction was obtained for RNH2   but not for ROH (R = octadecyl), proving that the most important   non-covalent interaction between oxidatively cleaned SWNTs and   octadecylamine is a salt formation. The outcome of the secondary   functionalization of carboxyl units is highly reproducible for   experiments carried out on the same batch of SWNT-(COOH)(n). Normalization of the outcome of the secondary functionalization to the   composition of the different batches of starting materials reveals an overall high reproducibility of the secondary function alizations. The   differences in outcome related to different commercial SWNT batches   from the same synthetic procedure is negligible compared to that   resulting from differences in overall carboxyl content after the   primary HNO3 oxidative cleaning step. Hence, the composition of   purified SWNT starting materials always needs to be assessed, in particular before drawing any conclusions concerning differences in   outcome from reaction systems involving different sources of SWNT  material.

Ämnesord

NATURVETENSKAP  -- Kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences (hsv//eng)

Nyckelord

Nanotubes

Nanotechnology

Functionalization

Esterification

Amidation

Chemistry

Kemi

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