Functionalization of TiO2 nanoparticles with bio-safe poly(vinyl alcohol) to obtain new poly(amide-imide) nanocomposites containing N, N′-(pyromellitoyl)-bis-L-leucine linkages

Nanocomposites (NCs) based on the reinforcement of polymers with nanoparticles (NPs) have attracted increasing attention for researchers. The goal of this study was production of new NCs based on poly(amide-imide) (PAI) and modified titanium dioxide (TiO2) NPs. Due to the tendency of the NPs for agglomeration, the surface of the TiO2 NPs was modified with poly(vinyl alcohol). Then the PAI was prepared from the polymerization reaction of N,N -(pyromellitoyl)-bis-L-leucine diacid with 4,4-diaminodiphenylmethane under green conditions. Finally, NCs were synthesized by incorporating modified TiO2 NPs into the PAI matrix by ultrasonic irradiation. The resulting NCs were studied by Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analyses (TGA), field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). TGA results showed good thermal stability for the prepared NCs by addition of the modified TiO2 NPs into the PAI matrix. Results of TEM and FE-SEM showed that the modified TiO2 NPs homogenously dispersed in the PAI matrix.