Polyurea-functionalized multiwalled carbon nanotubes: synthesis, morphology, and Raman spectroscopy

Gao, C., Jin, Y.Z., Kong, H., Whitby, R.L.D., Acquah, S.F.A., Chen, G.Y., Qian, H.H., Hartschuh, A., Silva, S.R.P., Henley, S., Fearon, P., Kroto, H.W. and Walton, D.R.M. (2005) Polyurea-functionalized multiwalled carbon nanotubes: synthesis, morphology, and Raman spectroscopy Journal of Physical Chemistry B, 109 (24). pp. 11925-11932. ISSN 1520-5207

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Abstract

An in situ polycondensation approach was applied to functionalize multiwalled carbon nanotubes (MWNTs), resulting in various linear or hyperbranched polycondensed polymers [e.g., polyureas, polyurethanes, and poly(urea-urethane)-bonded carbon nanotubes]. The quantity of the grafted polymer can be easily controlled by the feed ratio of monomers. As a typical example, the polyurea-functionalized MWNTs were measured and characterized in detail. The oxidized MWNTs (MWNT-COOH) were converted into acyl chloride-functionalized MWNTs (MWNT-COCl) by reaction with neat thionyl chloride (SOCl2). MWNT-COCl was reacted with excess 1,6-diaminohexane, affording amino-functionalized MWNTs (MWNT-NH2). In the presence of MWNT-NH2, the polyurea was covalently coated onto the surfaces of the nanotube by in situ polycondensation of diisocyanate [e.g., 4,4'-methylenebis(phenylisocyanate)] and 1,6-diaminohexane, followed by the removal of free polymer via repeated filtering and solvent washing. The coated polyurea content can be controlled to some extent by adjusting the feed ratio of the isocyanato and amino groups. The structure and morphology of the resulting nanocomposites were characterized by FTIR, NMR, Raman, confocal Raman, TEM, EDS, and SEM measurements. The polyurea-coated MWNTs showed interesting self-assembled flat- or flowerlike morphologies in the solid state. The signals corresponding to that of the D and G bands of the carbon nanotubes were strongly attenuated after polyurea was chemically tethered to the MWNT surfaces. Comparative experiments showed that the grafted polymer species and structures have a strong effect on the Raman signals of polymer-functionalized MWNTs.

Item Type: Journal article
Subjects: C000 Biological and Biomedical Sciences > C700 Molecular Biology, Biophysics and Biochemistry
DOI (a stable link to the resource): 10.1021/jp051642h
Faculties: Faculty of Science and Engineering > School of Pharmacy and Biomolecular Sciences > Biomedical Materials
Depositing User: editor spbs
Date Deposited: 08 Nov 2007
Last Modified: 02 Jul 2013 14:20
URI: http://eprints.brighton.ac.uk/id/eprint/2669

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