In this project, a series of novel chiral and biodegradable poly(ester-imide)s ( PEI )s based on different amino acids, were synthesized. Some physical properties of them were investigated. For this purpose at first pyromellitic dianhydride , trimellitic anhydride and L-amino acids (L-phenylalanine, L-leucine, L-isoleucine, L-methionine) have been used for the preparation of optically active diacids .These diacids react with 4,4-thiobis(2-tert-butyl-5-methylphenol) via direct polycondensation by using tosyl chloride (TsCl)/ N,N -dimethylformamide (DMF)/Pyridine as condensing agent under conventional heating in order to prepare thermally stable and optically active PEIs. Favorable conditions in term of reaction time and temperature were also investigated. The resulting PEIs were obtained in good yield and exhibited inherent viscosities ranging from 0.13 to 0.19 dL/g. The chemical structure of polymers was confirmed by FT-IR, 1 H-NMR spectroscopy, elemental analysis and specific rotation. Thermal properties of polymers were studied by TGA curves. . In the next project, biological and biodegradability properties of synthetic polymers were investigated. In the end project, polyester/titania (PE/TiO 2 ) nanocomposites were prepared and characterized by FT-IR, XDR, SEM and TGA. The SEM results indicated that the nanoparticles were dispersed homogenously in PE matrix. TGA confirmed that the heat stability of the composite was improved.