In this thesis, new optically active nanostructure poly(amide-imide)s (PAI)s were synthesized via direct polycondensation reaction of diacids based on trimellitic anhydride and different amino acides with 4,4?-methylenebis(3-chloro-2,6-diethylaniline), using tetra-n butylammonium bromide and triphenyl phosphite as a condensing agent and green media. The formation of these nanostructure PAIs was confirmed by 1H-NMR, fourier transform inferared spectroscopy, specific rotation, elemental analysis, X-ray diffraction, field emission scanning electron microscopy (FE-SEM) and thermogravimetric analysis (TGA) techniques. The resulting polymers were obtained with good yield and moderate inherent viscosities ranging between 0.27 and 0.37 dL/g. The FE-SEM micrographs and X-ray diffraction showed that, the obtained PAIs were nanostructure and noncrystalline polymers. Also TGA exhibited that these polymers show good thermal stability and the decomposition temperature under the nitrogen atmosphere for 10% weight-loss temperatures is in excess of 380?C. All synthetic PAIs show high solubility in organic solvents, such as N,N'-dimethyl acetamide, dimethyl sulfoxide, dimethylformamide, N-methyl-2-pyrrolidone and sulfuric acid at room temperature. In next step, a new optically active 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 ?-aminopropyltriethoxyl silane as a coupling agent. The obtained polymer and inorganic metal oxide nanoparticles were used to prepare of PAI/TiO2 nanocomposites through ultrasonic irradiation. The formation of PAI was confirmed by 1H-NMR, fourier transform IR spectroscopy, specific rotation and elemental analysis. The resulting polymer was synthesized with good yield and moderate inherent viscosities around 0.27 dL/g. The resulting nanocomposites were also characterized by FT-IR, powder X-ray diffraction, FE-SEM, transmission electron microscopy (TEM) and TGA. Furthermore, morphology study of resulting NCs by FE-SEM and TEM analyses showed that TiO2 NP was dispersed homogenously in the polymer matrix. The obtained PAI/TiO2 NCs show also improved thermally stability compared with the pure polymer.TGA confirmed that the heat stability of the nanocomposites was improved in the presence of TiO2 nanoparticles. Transmittance behavior of the obtained PAI/TiO2 nanocomposites was investigated by UV–vis spectroscopy. Finally, the biodegradability of the monomers and prepared polymers was investigated in culture media and soil burial test for assessment of the susceptibility of these compounds to microbial degradation. The results showed that the synthesized monomers and theirs derived polymers are biologically active and nontoxic to microbial growth. The results showed that the synthesized monomers and theirs derived polymers were biologically active and nontoxic to microbial growth. Due to the existence of naturally occurring amino acids as biological chiral resources, it is predictable that these polymers to be biodegradable. In vitro toxicity studies and soil biodegradation test verified that prepared polymers could be decomposed by soil microorganisms and therefore they are biodegradable.