Investigation of the thermal stability of nitroxide capped polystyrene by TGA and Py-GC/MS

The thermal stability of nitroxide capped polystyrene is examined by TGA and pyrolysis-GC/MS. As opposed to technical polystyrene, these polymers (M_n > 30000 g mol^–1) show a characteristic decomposition step at 230–250°C. The volatile product of this step is mainly styrene, which results from retropolymerization. For some PS-N adducts terminator fragments can be identified. Prolonged isothermal treatment of PS-N adducts at their step temperature yields polystyrene without nitroxides. The loss of molecular weight is in the range of technical PS by the same treatment, but the polymers keep a narrow molecular weight distribution.