|M.Sc Student||Makarov Carina|
|Subject||The Structure of Composite Nanoparticles of Sol-gel|
Ceramics and Polymer
|Department||Department of Chemical Engineering||Supervisor||Professor Yachin Cohen|
Composite particles made of organic polymers and oxides such as silica find application in several areas such as: catalysis, chromatography, controlled release, as materials additives (fillers), optics, etc. A novel method for a one-step preparation of silica/hydrophobic linear-polymer composite nanoparticles, based on sol-gel chemistry has been used for the preparation of various types of particles with diameters of 200-500 nm. The thesis studies these composite nanoparticles in terms of their overall (outer) and inner structure, the surface coating and the physical properties of the polymers within the composite particles. The investigation was done by Small-Angle X-ray Scattering (SAXS) in conjunction with other physical methods of Thermal gravimetric analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC) and X-ray Diffractions (XRD). Using SAXS measurements with contrast variation, information on the inner structure of the nanoparticle’s composition and inhomogeneity was provided. The inhomogeneities of the inner particle structure have a characteristic dimension of about 7 nm. The presence of the polymer, and the increase in the surfactant content used for the particles preparation, result in a lower volume fraction of voids. The surface of the particles is heavily coated with the organic material. The crystallinity and the melting behavior of the entrapped polymers were unaffected by its confinement to the particles. Some of the particles were found to be coated by a nanometric shell of the respective polymer. Further applications of those particles can be based on this structural characterization.