A Step Towards High‐Molecular‐Weight Living/Controlled Polystyrene Using SG1‐Mediated Polymerization

The synthesis of high-molecular-weight living/controlled polystyrene by NMP was studied. The combination of Ac 2 O and alkoxyamines based on nitroxides TEMPO, TIPNO, and SG1 was tested at 130 °C. With TEMPO and TIPNO, dipole/dipole interactions led to a decrease in nitroxide concentration and an acceleration of the reaction. To minimize thermal auto-initiation and thus obtain high-M n PS, the temperature was lowered. At 90 °C, the use of BlocBuilder yielded PS of M n = 210 000 g · mol ―1 with a living fraction of 60%. Finally, new SG1-based nitroxides were used to perform the polymerization at 75 °C. Since these nitroxides were too constrained, the decrease in k c caused a loss of control and livingness for high-M n polymers.