Thermal behaviour of a series of novel aliphatic bridged polyhedral oligomeric silsesquioxanes (POSSs)/polystyrene (PS) nanocomposites: The influence of the bridge length on the resistance to thermal degradation

The thermal degradation of Polystyrene based nanocomposites, containing as fillers novel dumbbell-shaped bridged POSSs in which two identical silicon cages R7(SiO1.5)8 (R = isobutyl), are linked to aliphatic bridges (CH2)n of different lengths (n = 2, 4, 6, 8 and 10), was studied. Various nanocomposites were prepared by in situ polymerization of styrene in the presence of 5% of appropriate POSS. The obtained compounds were characterized by 1H NMR spectroscopy, to verify their actual filler content, which was slightly higher than that in starting mixtures, and by Differential Scanning Calorimetry (DSC) to determine glass transition temperature (Tg). Thermogravimetric (TG) and Differential Thermogravimetric (DTG) analysis, in both flowing nitrogen and static air atmosphere, were carried out and temperatures at 5% mass loss (T5%) were determined to investigate the resistance to the thermal degradation. The results obtained for various samples were compared with each other and with those of virgin Polystyrene, and were interpreted and discussed.