In this study, the surface of alumina nanoparticles (?-Al 2 O 3 ) was modified with citric acid (CA) for prevent of agglomeration, compatibility with the polymeric matrix and improve properties of nanocomposites (NCs). In this process, ultrasonic method was used as a fast, low cost and green way. Then, the optically active poly(amide-imide) (PAI) was synthesized by the polycondensation reaction of 1,5-naphthalenediamine and N -trimellitylimido-L-phenylalanine dicarboxylic acid in the presence of triphenyl phosphite and the molten tetra-n-butylammonium bromide. Next, PAI/?-Al 2 O 3 -CA NCs containing 5, 10 and 15 wt% of ?-Al 2 O 3 -CA were prepared by ultrasonic irradiation of ?-Al 2 O 3 -CA and the PAI. Finally, the ?-Al 2 O 3 -CA and NCs characterized by different method such as Fourier transform infrared spectra, X-ray diffraction (XRD), field emission scanning electron microscopy, transmission electron microscopy analysis and thermogravimetric analysis (TGA). According to XRD, surface modification did not have any influence on the crystal structure of Also, comparison between the TGA curve of the ?-Al 2 O 3 -CA and neat showed the presence of CA on the surface of . In the other investigation, the surface of ?-Al 2 O 3 modified with poly(vinyl alcohol) (PVA) a biocompatible and water soluble polymer and they used as filler for preparation of PAI/?-Al 2 O 3 -PVA NCs (PAPNCs). PVA on the surface of reduce the surface energy and prevent agglomeration of the ?-Al 2 O 3 . According to the results of the different methods, the modified were uniformly dispersed in the PAI matrix and also improved the thermal stability of the NCs.
