Synthesis Of Novel Inorganic-Organic Hybrid Bonding Agents

This thesis addresses the challenge of effectively bonding plastics to metals by developing novel bonding agents based on hybrid inorganic-organic copolymer matrices. These agents combine organic azides—specifically sulfonyl azides, azidoformates, and perfluorophenyl azides—with inorganic polymethylsilsesquioxane (PMSSQ). The objective was to produce bonding agents capable of adhering to plastic substrates through the thermal degradation of the azide groups to generate nitrenes, which are known to participate in CH insertion reactions, while simultaneously forming bonds with metal surfaces via silanol groups, from non-condensed PMSSQ, that undergo heat-induced condensation with metallic oxides on the substrate. To achieve this, azide monomers were synthesised and polymerised, followed by detailed thermal and kinetic analyses using thermogravimetric analysis (TGA) and kinetic modelling methods, such as the Coats-Redfern method, and model-free methods such as the Kissinger kinetic analysis method, to determine activation energies and Arrhenius parameters, thereby elucidating the degradation mechanisms of the azide components. Extracting kinetic information regarding azide decomposition is novel and has not been attempted using TGA kinetics before. PMSSQ vinyl pre-polymers were synthesised with vinyl functional groups, such as methacrylates and styrenes, to facilitate the grafting of vinyl azide monomers. The copolymerisation of these vinyl azide monomers with the PMSSQ pre-polymer was conducted using reversible addition-fragmentation chain transfer (RAFT) polymerisation techniques, resulting in the formation of PMSSQ-co-azide hybrid polymers. The adhesive properties of these hybrid materials were evaluated through cross-cut and lap shear testing. The hybrid copolymers, formed through the integration of azide and PMSSQ components, generated cross-linked networks with strong adhesion to metallic substrates, as demonstrated by high lap shear strength and resistance to delamination in cross-cut tests. These results provide new insights into the development of PMSSQ-co-azide copolymers with enhanced surface adhesion properties for metals and specific plastics, indicating their potential use for diverse material applications.