In the first project, the synthesis of nanocomposites (NCs) based on poly(vinyl chloride)/titania (PVC/TiO 2 ) were performed. For this goal, initially, the hydrophilic surface of TiO 2 nanoparticle (NPs) for better compatibility with PVC matrix, was modified as double layers with citric acid (CA) and vitamin C (VC) biomolecules for the first time. The process was accomplished under ultrasonic method as a fast, low cost and green way. The resulting modified were characterized by various techniques including Fourier transform infrared (FT-IR), X-ray diffraction )XRD( and their morphology will be investigated by field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The loading percent of surface modifier agents (CA VC) on the surface of modified were investigated by TGA analysis. The mean particle size of modified were estimated about 22 nm. The various percents (4, 8 and 12) of the modified was incorporated into the PVC matrix using ultrasonic conditions for the preparation of PVC NCs. The resulting nanocomposites were characterized using several techniques including FT-IR, XRD and UV-Vis spectroscopy. Their morphology were studied by FE-SEM and TEM. The thermal and mechanical properties of NCs were studied by TGA and mechanical tests. The nanometer scale dispersion of in the polymer matrix by normal distribution curve obtained from NC 4 wt% was confirmed. The TGA results showed an increase in the thermal stability of nanocomposite films in comparision to the pure polymer. According to the UV-Vis spectrum, the nanocomposite films showed more absorption incomparison to the pure polymer. In the second project, poly(vinyl alcohol) (PVA) was chosen as the polymer matrix and PVA/TiO 2 NC films were prepared and the effect of the presence of modified with various loading percents (4, 8, and 12) on morphological, mechanical and thermal properties of the NCs was investigated using different techniques including FT-IR, XRD, FESEM, TEM, TGA, UV-Vis spectroscopy, and mechanical test. The nanometeric and uniform dispersion of the in the polymer matrix were interpreted by TEM of NC 8 wt%. According to the TGA thermograms, the addition of the modified into the polymer matrix leads to an increase in the thermal resistance.