In this thesis, the surface modification of the alumina nanoparticles (NPs) was performed in order to prevent aggregation between the hydrophilic surface ofNPs and improvement of NPs compatibility with the polymer matrix. The modification was performed using vitamin B 1 , as a biocompatible molecule, under ultrasonic irradiation. The modified aluminaNPswere characterized using FT-IR, XRD, TGA, FE-SEM and TEM. Based on the XRD patterns, the surface modification had no effect on the crystalline structure of the alumina NPs. After the surface modification of the NPs, poly(vinyl chloride) (PVC) was selected as the polymer matrix due to its good structural characteristics. Then, the PVC/ a -Al 2 O 3 -VB 1 nanocomposites (NCs) containing 3, 5, and 7 wt % of the modifiedNPs were synthesized under ultrasonic irradiation. The resulting NCs were characterized by FT-IR, XRD, TEM, FE-SEM, TGA, UV-Vis, mechanical testing and measurement of the contact angle. The study of the NCs morphology with TEM showed a homogenous dispersion of NPsin the polymer matrix. The NCs showed more UV-Vis absorption than the pure polymer. In the second study, poly(vinyl alcohol) (PVA) was chosen as another polymer matrix. PVA contains lots of hydroxyl groups which can react with the hydroxyl and amine functional groups of vitamin B 1 , even with hydroxyl functional groups on the surface of the aluminaNPs. In addition, PVA is nontoxic, biodegradable and water soluble. The measurement of the contact angle showed more hydrophility of the NCs in comparison with the pure PVA.