Bionanocomposites preparation and characterization: Dispersion of surface modified ZnO nanoparticles in optically active poly(amide-imide) derived from 3,5-diamino-N-(4-hydroxyphenyl)benzamide and amino acid

Bionanocomposites (BNCs) containing 4, 8 and 12% (w/w) modified ZnO nanoparticles (NPs) were successfully prepared by homogenous dispersion of these NPs in an optically active poly(amide-imide) (PAI) matrix through an ultrasonic process. PAI was synthesized via solution polycondensation of 3,5-diamino-N-(4-hydroxyphenyl) benzamide and N,N-(pyromellitoyl)-bis-L-phenylalanine diacid chloride at low temperature. The ZnO NPs were treated with γ-aminopropyltriethoxysilane (KH550) as a coupling agent to change the surface property of NPs from hydrophilic to hydrophobic nature for better dispersion in PAI matrix. The obtained BNCs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction, atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and thermogravimetry analysis. AFM studies of the BNCs suggest that the ZnO NPs of 20–50 nm in diameter were dispersed in polymer matrices. FE-SEM and TEM results also confirmed the formation of well-dispersed nano ZnO in the PAI matrix.