In this research project, at first, a new series of optically active, nanostructured and thermally stable poly(amide-imide)s derived from 3,5-diamino- N -(4-hydroxyphenyl)benzamide and 3,5-diamino- N -(3,4-dihydroxyphenethyl)benzamide as diamine monomers via direct polycondensation reaction with different amino acid-containing diacids was prepared. Polymerization reactions were performed under two main methods: classical heating method and microwave irradiation. Solvents commonly used in chemical reactions are highly toxic and have adverse effects on human health and the environment pass. To prevent this, the polymerization reactions were carried out in tetrabutylammonium bromide as a molten ionic liquid salt and in the presence of triphenyl phosphite as the condensing agent. The effect of reaction variables on the physical properties of the prepared polymers was investigated. Structure of the obtained polymers was studied by Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance, ultraviolet-visible, optical specific rotation and elemental analysis. Thermal stability of the polymers was studied using thermogravimetric analysis (TGA) technique. The obtained results showed that the polymers have good thermal stability. All of these polymers have very good solubility due to amino acid flexible components and large hangings, which prevents the polymer chains from approaching. These polymers are also capable to form traarent thin films. Crystallinity of the polymers was investigated by X-ray diffraction (XRD) technique. The diffraction patterns showed that the synthesized polymers were amorphous. This property is due to the presence of amide, imide, methyl and methylene flexible groups, which prevent the interaction between the polymer chains. The surface morphology of polymers was also studied by field emission scanning electron microscopy (FE-SEM) analysis. The resulting images showed that the polymer particles were almost spherical with a diameter less than 100 nm. In the next section, polymer-based nanocomposites containing carboxylated multi-walled carbon nanotubes were prepared. By ultrasonic-assisted solution blending method, carbon nanotubes were dispersed in the polymer matrix with different weight percentages of 5, 10, and 15% by weight relative to the weight of the polymer and the related naocomposites were prepared. Composite thin films were fabricated by mixing of carbon nanotubes into the polymer solution and casting of it. The fabricated composites were investigated and studied by different analytical methods like FT-IR, XRD, TGA, FE-SEM and transmission electron microscopy (TEM). The obtained informations from TGA showed that the thermal stability of the nanocomposites was increased with the increasing of carbon nanotubes content. The mechanical properties of the nanocomposite films were also studied. The elastic modulus, tensile strength, and strain were obtained from this investigation. The results showed that with increase in weight percentage of nanotubes in the polymer matrix, the mechanical properties of the nanocomposites were improved. In another section of the project, carbon nanotubes were functionalized with natural amino acids under microwave irradiation. The formation of new functional groups was confirmed using different techniques. Then, S-valine-functionalized carbon nanotubes were used as fillers in the polymer matrix. A new series of chiral bionanocomposites were prepared. Structural characterization of the bionanocomposites was performed with different techniques. Thermal stability and mechanical properties of nanocomposite films resulted favorable data. The Obtained micrographs from FE-SEM and TEM depicted uniform dispersion of functionalized carbon nanotubes in the polymer matrix.