In the present communication we report the functionalisation of MWCNT using a 1,3,5-triazine, namely melamine. The MWCNTs (Baytubes, Germany) were dispersed in ethanol for 16 hours and allowed to react with melamine at 80°C for 1 hour or 16 hours. The resulting MWCNT-melamine adducts were heated at 250°C under vacuum in order to remove the non-chemisorbed melamine. Thermogravimetric and elemental analyses indicated that a 16 hour vacuum treatment was enough to remove almost 95% of the melamine present in the original adduct. The nitrogen-content of sample decreased from 0.017 mol/gram (for the MWCNT-melamine adduct) to 0.002 mol/gram (the adduct was heated for 16 hours under vacuum). During the treatment at 250°C the melamine can also interact further with the MWCNT yielding either to a physical mixture, or the product of cycloaddition reactions between the 1,3,5-triazine rings and the MWCNTs. Based on the strong resemblance of the Raman spectra of the pristine MWCNTs with that of the MWCNT-melamine, i.e. all samples have spectra with the same intensity for the D and G bands, we suppose that the 1,3,5-triazine rings interact with the graphene layers of MWCNTs by the so-called p-p interactions. Therefore all materials prepared in this work can be regarded as non-covalently functionalised MWCNTs.

The functionalisation of MWCNTs with melamine can bring about enhanced interactions with polymeric matrices. For instance, differential scanning calorimetry results indicated a +10°C shift of the glass transition temperature of an epoxy resin based on bisphenol A (DER 331, Dow Chemical, Germany) and an amine hardener (A2954, Huntsman, Germany) at loading close to 0.10 wt-%. The similar nanocomposite containing 0.10-wt% of pristine MWCNT has a glass transition temperature slightly lower than the neat resin, which is in accordance with previous publications of our group [1].

References:

[1] J. Sumfleeth, L. A. S. A. Prado, M. Sriyai, K. Schulte Adv. Funct. Mater. 2008 (submitted)

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