Production and characterization of novel nanocomposites based on poly(amide‐imide) containing N‐trimellitylimido‐l‐alanine diacid and 4,4′‐diaminodiphenylmethan segments reinforced with grafted nano‐ZnO by citric acid as a biological ligand

Nanocomposite (NC) materials containing polymers and dispersed nanofillers such as nanoparticles (NPs) are one of the most attractive topics due to their potential ability to provide high‐performance novel materials. In this study, novel optically active poly(amide–imide)/zinc oxide nanocomposites (PAI/ZnO NCs) containing different amounts of modified ZnO NPs were prepared using an ultrasonic assisted. For this reason, at first the surface of ZnO NPs was successfully modified with citric acid (2‐hydroxypropane‐1,2,3‐tricarboxylic acid, C₆H₈O₇) (CA) as a coupling agent to improve dispersion stability of NPs and increase the possible interaction such as hydrogen bonding, physical van der Waals between NPs and PAI matrix. Then, the optically active PAI chains were formed from the polymerization of N‐trimellitylimido‐l‐alanine diacid (3) with 4,4′‐diaminodiphenylmethane (4) under green conditions by using molten tetra‐n‐butylammonium bromide and triphenyl phosphite as a condensing agent. Finally, modified ZnO NPs with CA (ZnO‐CA NPs) were incorporated into the obtained PAI matrix to prepare chiral PAI/ZnO‐CA NCs through the ultrasonic irradiation. PAI/ZnO‐CA NCs were characterized by Fourier transform infrared spectra, X‐ray diffraction patterns, field‐emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and UV–visible techniques. The TGA results proved that the thermal stability of obtained NCs was improved compared with the pure polymer. Also, the TEM and FE‐SEM images showed that NPs were uniformly dispersed in the polymer matrix on nanoscale. POLYM. COMPOS., 39:2394–2402, 2018. © 2016 Society of Plastics Engineers