Chemical surface coating of MWCNTs with riboflavin and its application for the production of poly(ester-imide)/MWCNTs composites containing 4,4′-thiobis(2-tert-butyl-5-methylphenol) linkages: Thermal and morphological properties

In this work, carboxylated multi-walled carbon nanotubes (MWCNTs) were functionalized with riboflavin as a biological molecule under microwave irradiation. Solution blending method was used to incorporate different modified MWCNTs content (5, 10, and 15 wt %) into a chiral and biodegradable poly(ester-imide) (PEI) to fabricate PEI-based nanocomposites. The products were characterized for assessing the spectroscopic, thermal, and morphological properties by Fourier-transform infrared spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction, transmission electron microscopy (TEM), and field-emission scanning electron microscopy (FESEM). Optically active PEI was prepared by step-growth polymerization of amino-acid-based diacid and aromatic diol. Functionalized MWCNTs were well dispersed in the PEI matrix and their distribution was homogeneous. This was confirmed by morphology study of the fractured surfaces of nanocomposites by FESEM and TEM. The addition of functionalized MWCNTs improved the thermal stability of NCs compared to the pure PEI. It was found from TGA data that temperature at 10% weight loss was increased from 409°C for pure PEI to 417, 420, and 424°C for nanocomposites containing 5, 10, and 15% functionalized MWCNTs, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42908.