Effect of amino acid-functionalization on the interfacial adhesion and behavior of multi-walled carbon nanotubes/poly(amide-imide) nanocomposites containing thiazole side unit

A simple and efficient method for chemical functionalization of multiwalled carbon nanotubes (MWCNT)s with S-valine amino acid was discussed to give enhanced solubility and dispersability by rapidly and efficiently generating an appreciable amount of hydrophilic functional groups using microwave radiation. The chemical and aggregated structures of functionalized MWCNTs (f-MWCNTs) were characterized by means of field emission and transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis (TGA) measurements. The surface-modified MWCNTs showed better chemical stability in common solvents. The f-MWCNT/poly(amide-imide) (PAI) hybrid films were prepared with different f-MWCNTs content (5–15 wt.%) by solution blending method. The dispersion of CNTs can be improved by the functional groups, which is attributed to the carbonyl groups on the PAI matrix itself. Microscopic observations showed that the dispersion of the CNTs was improved by the amino acid groups on the MWCNTs and functional groups on the PAI. TGA results showed that the hybrid films exhibit a good thermal stability. Tensile mechanical test was measured for the prepared composites and depicted by an increase in the elastic modulus with increasing MWCNTs content.