Rapid and green functionalization of multi-walled carbon nanotubes by glucose: structural investigation and the preparation of dopamine-based poly(amide-imide) composites

Functionalization of multi-walled carbon nanotubes (MWCNTs) by glucose was performed through esterification reaction. The reaction was carried out in water, in the presence of N,N'-carbonyldiimidazole as a catalyst. Glucose-functionalized MWCNTs (MWCNTs-Gl) were characterized by a set of methods including Fourier-transform infrared spectroscopy, X-ray diffraction, field emission scanning, and transmission electron microscopy. Thermogravimetric analysis (TGA) results also demonstrated the presence of organic portions of the functionalized MWCNTs. MWCNT-Gl/poly(amide-imide) (PAI) composite films with different MWCNTs-Gl content (5, 10, and 15 wt%) were prepared by ultrasonication-assisted solution blending method. Microscopic observations showed that the dispersion of the MWCNTs-Gl was improved by the organic groups on the MWCNT surface and functional groups on the PAI. TGA results showed that the hybrid films exhibited a good thermal stability. According to mechanical tensile tests, the tensile strength and the Young's modulus of the MWCNT-Gl/PAI composites were increased with increasing MWCNTs-Gl content.