New polymer-inorganic oxide hybrid films for optoelectronic devices.

This thesis reports research into the development of metal oxide-polymer hybrids as novel materials for optoelectronic packaging. Transparent hybrids have been successfully achieved, the chemistry of the interaction between organic-inorganic phases in the hybrid has been studied and the optical and thermal properties are reported. Polyacrylate-silica hybrids have been synthesised in acidic media via the sol-gel process from TEOS and acrylate monomer to yield a sol which has been coated and cured using UV irradiation, resulting in transparent and semi-transparent films. Various acrylates have been used and organically modified alkoxysilanes have been introduced in order to obtain hybrids of type I and II with different properties. For the characterisation of these films 13C NMR, 29Si NMR, FTIR and Raman spectroscopies and scanning electron microscopy (SEM) have been used. Ellipsometry has been used to measure refractive indices, thickness and to estimate thermal expansion coefficients. Polyacrylate-silica hybrids have been expanded with the synthesis and characterisation of polyacrylate-titania and polyacrylate-hafhia, wherein the acrylate plays a dual role as a complexing agent and a polymerisable species. These hybrids lead to transparent films with higher refractive indices than polyacrylate-silica hybrids. Epoxy resins cured with anhydride and imidazole catalyst are also reported and the incorporation of titania and zirconia nanoparticles is explored. Good miscibility and transparency are found when zirconia nanoparticles modified by silane coupling agents are utilised. The modification of the nanoparticles is studied by means of FTIR, 29Si NMR and Raman spectroscopies while the modified epoxy resins are studied by FTIR and Raman spectroscopy and SEM. Thermal studies are carried out with differential scanning calorimetry (DSC) and dynamic mechanical thermal analysis (DMTA). Finally, the polymerisation kinetics of the modified epoxy resins are reported