Effects of Peripheral Architecture on the Properties of Aryl Polyhedral Oligomeric Silsesquioxanes

The effects of the peripheral architecture on the macroscopic properties of eight symmetric and asymmetric aryl polyhedral oligomeric silsesquioxane (POSS) molecules are described. These POSS materials were synthesized in our laboratory and characterized by single-crystal and powder Xray diffraction techniques, as well as differential scanning calorimetry, thermogravimetric analysis, mass spectrometry, and Fourier transform infrared spectroscopy. The peripheral aryl architecture, although similar in most cases, was found to significantly influence observed thermally induced phase transitions, mass loss during decomposition, and heat capacity. These properties are correlated to POSS assembly, molecular interactions, and the specific attributes of peripheral structure and connectivity to the inorganic core.