Preparation of Highly Crystalline Octavinyl Silsesquioxane Building Blocks via Sol-Gel Technique

Document Type: Research Paper


Nanochemical Engineering Dep., Faculty of Advanced Technologies, Shiraz University, Shiraz, Iran


Polyhedral oligomeric silsesquioxanes (POSSs) are a class of hybrid materials with a unique structure and properties originated from a combination of organic functional groups and inorganic silica core. Not well-defined synthesis process generally suffers from multistep, complex and especially time-consuming procedure from days to weeks and months. Consequently, in the present study, the effect of various parameters on the synthesis of octavinyl POSS (OV-POSS) nanostructure such as temperature, monomer concentration, reaction time, and rate of monomer addition are investigated. Finally, OV-POSS crystallization is produced under optimal condition through single-step hydrolytic condensation of vinyltrimethoxysilane (VTMS) with 72% yield and a high crystallinity (above 90%) during a reduced time interval of 5 h at 60 °C at a 20 μl.min-1 monomer addition rate. Morphology and size of the as-prepared samples are characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses. Also, the chemical structure is predicted using nuclear magnetic resonance (NMR), FTIR, and EDX.