Improved covalent functionalization of multi-walled carbon nanotubes using ascorbic acid for poly(amide–imide) composites having dopamine linkages

Abstract

Ascorbic acid has been covalently linked to multi-walled carbon nanotubes (MWCNTs). The structures of the functionalized MWCNTs were characterized with Fourier-transform infrared spectroscopy. Thermogravimetric analysis results also demonstrated the presence of organic portions of the functionalized MWCNTs. Polymer composites based on a nanostructured poly(amide–imide) (PAI) were fabricated by an ex situ technique with 5, 10 and 15% loading by weight. Composite films were made by the solvent casting method. The thermal stability of the composites increased with even a small amount of modified MWCNT added. Tensile tests were conducted and depicted an increase in the elastic modulus with increasing MWCNTs content. X-ray diffraction study of the composites also indicated that the composites incorporated MWCNTs in the polymer chain.