The preparation of cation-functionalized multi-wall carbon nanotube/sulfonated polyurethane composites

Covalent functionalization of multi-wall carbon nanotubes (MWCNTs) with minimal alteration to the MWCNT surface is important to achieve homogenously dispersed carbon nanotubes while maintaining their unique mechanical and electrical properties. Carboxylic acid derivatized MWCNTs (MWCNT-COOH) were co...

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Bibliographic Details
Published in:Carbon (New York) 2013-04, Vol.54, p.133-142
Main Authors: Gao, Renlong, Ramirez, Sean M., Inglefield, David L., Bodnar, Robert J., Long, Timothy E.
Format: Article
Language:English
Subjects:
Cations
Covalence
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Field emission
Materials science
Multi wall carbon nanotubes
Nanoscale materials and structures: fabrication and characterization
Nanostructure
Nanotubes
Physics
Polymer matrix composites
Polyurethane resins
Transmission electron microscopy
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Summary:Covalent functionalization of multi-wall carbon nanotubes (MWCNTs) with minimal alteration to the MWCNT surface is important to achieve homogenously dispersed carbon nanotubes while maintaining their unique mechanical and electrical properties. Carboxylic acid derivatized MWCNTs (MWCNT-COOH) were covalently functionalized with 3,3′-iminobis(N,N-dimethylpropylamine) (DMPA). Upon subsequent quaternization of DMPA, dendritic ammonium cation-functionalized MWCNTs (MWCNT-DMPA+) were formed, where two ammonium cations were incorporated per amide site. Thermogravimetric analysis and X-ray photoelectron spectroscopy demonstrated successful covalent functionalization and formation of the surface-bound ammonium salt. Raman spectroscopy and atomic force microscopy indicated the absence of an appreciable decrease in the MWCNT aspect ratio. Compared with pristine MWCNTs and MWCNT-COOH, MWCNT-DMPA+ exhibited enhanced dispersibility in N,N-dimethylformamide (DMF) as observed with UV–Visible spectroscopy and transmission electron microscopy (TEM). In addition, blending the cation-bound MWCNT-DMPA+ with anion-bound sulfonated polyurethane in DMF generated novel composites with a nanotube content ranging from 0.5 to 5wt.%. Characterization of the composite films using both field emission scanning electron microscopy and TEM revealed that MWCNT-DMPA+ exhibited uniform dispersion in sulfonated polyurethane matrices even at 5wt.%. Tensile analysis showed that the modulus of the sulfonated polyurethane matrix linearly increased with MWCNT-DMPA+ content.
ISSN:0008-6223
1873-3891
DOI:10.1016/j.carbon.2012.11.010