Effect of Solvent properties on Crystallinity and Morphology of Octavinyl-POSS: A Comparative Study

Polyhedral Oligomeric Silsesquioxanes (POSSs) are a class of hybrid structures synthesized through hydrolytic condensation (Sol-Gel method) of trifunctional silane monomers under specific conditions. Octavinyl silsesquioxane (OVS) nanostructures are comprised of a rigid inorganic silica core surrounded by vinyl functional groups with an under-developed synthesis procedure. Generally, POSS morphology, yield and crystallinity depend strongly on synthesis conditions such as solvent type, synthesis temperature, sequence of reagents addition, water/monomer molar ratio, etc. In this study, effect of solvent properties on the formation of OVS compounds, their morphology and crystallite size was studied under specific conditions. Finally, n-pentanol and butanol as the most efficient solvents were suggested according to solvent characteristics, theoretical background reported in previous studies and experimental results. Different characterization techniques such as XRD to investigate crystallinity and crystallite size, FE-SEM and TEM to determine the morphology, EDX to identify elemental and chemical composition, C-NMR and 1H-NMR to confirm the attachment of vinyl groups and FTIR to define chemical bonds, were employed to confirm the formation of the as-prepared structure. Based on the results, butanol and n-pentanol represent the best results regarding crystallinity and size by optimizing other influential parameters.