Synthesis and thermal characterization of mono alkyl hepta phenyl POSS / PS nanocomposites

Polyhedral Oligomeric Silsesquioxane (POSS)/Polystyrene (PS) nanocomposites were synthesized by in situ polymerization of styrene, in the presence of POSSs of general formula R7R′(SiO1.5)8, where R = phenyl and R′ = -(CH2)7-CH3, and were characterized by FTIR, 1H NMR and SEM spectroscopy, to verify the interaction and dispersion of the filler with/into the polymeric matrix. The kinetic of degradation was studied to find a correlation with the level of POSS dispersion in polymer matrix and to evaluate the resistance to thermal degradation of the synthesized nanocomposites. To this aim, the temperature at 5% mass loss (T5%) was take into consideration and the activation energy (Ea) of degradation were determined through literature method. The results lead us to speculate about the role of the POSS cage vertices on the influence of filler dispersion into the matrix by the comparison with similar alkyl-POSS/PS nanocomposites studied by us in the past. Thermogravimetric analysis (TGA) suggested a good improvement of the resistance to the thermal degradationin respect to neat polymer, and showed that the presence of phenyl groups at the vertices of the POSS cage led to a better dispersion and thus to a thermal stability improvement.