Synthesis Of Polyhedral Oligomeric Silsesquioxane (POSS) Derivatives

The search for new nanofillers has led to development of new organic-inorganic hybrid materials such as polyhedral oligomeric silsesquioxanes (POSS).1 POSS is a cubeoctameric molecule with an internal structure of silicon and oxygen that is covered outside by organic substrates. The POSS molecules having cubic inorganic core with the composition of R8Si8O12 or R1R7Si8O12 are the most studied systems. R groups (organic shell) can be varied from hydrogen to alkyl (methyl, isobutyl, cyclopentyl or cyclohexyl, etc.), alkylene, or arylene.2 Interest in POSS materials is based on the facts that their rigid framework closely resembles that of silica and that they offer a unique opportunity for preparing truly molecularly dispersed nanocomposites. The POSS chains act like nanoscale reinforcing fibers, producing extraordinary gains in heat resistance.3 A novel octakis(3-propyl thiophenolate)-octasilsesquioxane was successfully synthesized via nucleophilic substitution on octakis(3-chloropropyl)octasilsesquioxane using sodium thiophenolate in aprotic dimethylformamide as a solvent. Complete substitution proceeded at room temperature product in high yield. The reaction products were characterized by 1H, 13C, and 29Si NMR spectroscopy; confirming the structure of the cubic T8 cage and demonstrating that the substitution reaction on eight side chains progressed smoothly under ambient conditions without any cage rearrangement or cage decomposition

کلیدواژه ها:

Polyhedral Oligomeric Silsesquioxane (POSS) Polymers ، POSS Macromers ، Thermoplastics ، Thermosets ، Thermal and Mechanical Properties