Investigation on synthesis and morphology characteristic of novel chiral poly(amide-imide)/TiO2 nanocomposites derived from L-isoleucine-based diacid and 4,4'-methylenebis(3-chloro-2,6-diethylaniline)

In the present investigation, a new optically active poly(amide–imide) (PAI) was synthesized from the polymerization reaction of N-trimellitylimido-L-isoleucine diacid with 4,4′-methylenebis(3-chloro-2,6-diethylaniline) using molten tetra-n-butylammonium bromide and triphenyl phosphite as a condensing agent and green media. Then the surface of titanium dioxide (TiO₂) nanoparticles was modified with γ-aminopropyltriethoxyl silane as a coupling agent. The obtained polymer and inorganic metal oxide nanoparticles were used to prepare of PAI/TiO₂ nanocomposites (NCs) through ultrasonic irradiation. The formation of PAI was confirmed by ¹H NMR, fourier transform IR spectroscopy (FT-IR), specific rotation and elemental analysis. The resulting polymer was synthesized with good yield and moderate inherent viscosities around 0.27 dL/g. The resulting NCs were also characterized by FT-IR, powder X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The TEM and FE-SEM results indicated that the nanoparticles were dispersed homogeneously in PAI matrix on nanoscale. TGA confirmed that the heat stability of the NCs was improved in the presence of TiO₂ nanoparticles. Transmittance behavior of the obtained PAI/TiO₂ NCs was investigated by UV–vis spectroscopy.