: In this thesis, modified silicon dioxide (SiO 2 ) nanoparticles () with vitamin B 9 were used for the preparation of poly(vinyl alcohol) (PVA) and polycaprolactone (PCL) nanocomposites (NCs). In order to avoid the agglomeration of SiO 2 , the were first modified with the biocompatible VB 9 modifier and subjected under ultrasonic waves. Modified SiO 2 -VB 9 were studied by various analyses such as field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). FE-SEM images showed spherical morphology for modified . TGA analysis confirmed the presence of about 6 wt% of VB 9 molecules on the surface of SiO 2 . With the help of TEM images and its histograms, the mean size of the modified SiO 2 -VB 9 was estimated to around 22 nm. In the first project, PVA-based NC films were prepared using various percentages of modified (2, 5, and 8 wt% as compared to the polymeric matrix). SiO 2 -VB 9 /PVA NC films prepared using various techniques including FE-SEM, TEM and mechanical properties were investigated. FE-SEM images showed the presence of spherical SiO 2 -VB 9 in PVA matrix. TEM images of SiO 2 -VB 9 /PVA 5 wt% NC film indicated that the average size were about 10 nm. The study of mechanical properties showed that the flexibility of NC films increased compared to the pure PVA. In the second project, modified SiO 2 were used to prepare NC films based on PCL. SiO 2 -VB 9 /PCL NC films were prepared using various techniques such as FE-SEM, TEM, and mechanical properties. TEM images and histograms of SiO 2 -VB 9 /PCL 5 wt% NC film indicated that the average size were about 29 nm. FE-SEM images showed uniform presence of modified in the PCL matrix. The study of mechanical properties indicated that SiO 2 -VB 9 /PCL 5 wt% NC film has more flexibility. By studying the bioactivity properties of SiO 2 -VB 9 /PCL NC films, it was found that SiO 2 -VB 9 /PCL 5 wt% NC films formed more hydroxyapatite layers. FE-SEM images showed the presence of hydroxyapatite layers on the samples, and EDX results confirm the presence of both Ca and P elements in the samples, indicating the formation of hydroxyapatite on the samples.
