Synthesis and thermal characterization of monosubstituted octaphenyl POSS/polystyrene nanocomposites

Four novel polyhedral oligomeric silsesquioxanes/polystyrene (POSS/PS) nanocomposites, having formula R7R '(1)(SiO1.5)(8)/PS (where R = C6H5- and R ' = p-C6H4-X, with X = -CH3, -OCH3, -F, -Cl) were synthesized by in situ polymerization of styrene, in the presence of 5% w/w of POSS. The obtained nanocomposites were characterized by H-1-NMR spectroscopy and by the glass transition temperature (T-g) determination. The thermal degradations of nanocomposites were thus carried out in thermobalance, in the scanning mode, in the temperature range r.t.-700 degrees C, in both flowing nitrogen and static air atmospheres. Temperature at 5% mass loss (T-5%) was determined as parameter measuring the resistance to thermal degradation. The obtained T-5% values of nanocomposites were largely higher than those found for PS, which was also degraded for comparison in the same experimental conditions, thus indicating higher resistance to thermal degradation in respect to neat polymer. Also, the sameness of nanocomposites T-5% values was interpreted and explained.