Manufacture of zinc oxide/chiral poly(amide-imide)-functionalized amino acid and thiazole bionanocomposites

Abstract

In this work, novel optically active poly(amide-imide)/zinc oxide bionanocomposites (PAI/ZnO BNCs) containing l-valine moiety in the main chain were prepared via a simple and inexpensive ultrasonic irradiation process. Chiral PAI was synthesized by direct polycondensation reaction of N,N′-(pyromellitoyl)-bis-valine with 3,5-diamino- N-(thiazol-2-yl)benzamide in the tetrabutyl ammonium bromide/triphenylphosphite as a green solvent system. Due to the high surface energy and the tendency for agglomeration, the surface of ZnO nanoparticles (NPs) was modified with γ-aminopropyltriethoxysilane. PAI/ZnO BNCs containing 4, 8, and 12% of NPs were successfully fabricated through ultrasonic irradiation technique. The obtained BNCs were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA), x-ray diffraction, ultraviolet–visible spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy (TEM) techniques. TGA data indicated an increase in thermal stability of the BNCs when compared with the pure polymer. From the TEM image of PAI/ZnO BNCs, it can be found that the surface-modified ZnO NPs, with a diametric size of less than 35 nm, are uniformly dispersed in the PAI matrix.