The nanocomposites of zinc oxide/ L -amino acid-based chiral poly(ester-imide) via an ultrasonic route: Synthesis, characterization, and thermal properties
In this investigation, a chiral poly) ester-imide) (PEI) via direct polyesterification of N,N′-(pyromellitoyl)-bis-(L-tyrosine dimethyl ester) and N-trimellitylimido-L-methionine was prepared using the tosyl chloride/pyridine/N,N′-dimethylformamide system as a condensing agent. This approach allows the insertion of two natural amino acids into the polymer backbone and the creation of a bioactive polymer. From the chemical point of view, the ester groups impart to the polymer's main and side chain increased sensibility to hydrolysis that can cause chain breaking. Therefore, this polymer is expected to be biodegradable and could be classified as an eco-friendly polymer. The polymer also had a useful level of thermal stability associated with excellent solubility. PEI/zinc oxide bionanocomposites were subsequently prepared by an ultrasonic method as a simple and inexpensive route, using ZnO nanoparticles (ZnO-NPs) modified by 3-aminopropyltriethoxylsilane (KH550) as a coupling agent. The structure and properties of the obtained BNC polymers were confirmed by Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The direct proofs for the formation of the true BNC polymers were provided by TEM. Also, the morphology study of the synthesized polymer-based BNCs showed well-dispersed ZnO-NPs in the polymer matrix by FE-SEM analysis. TGA studies indicated that an increase of the NP content led to an enhancement of the thermal stability of the new BNC polymers.