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 degrees 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.