A Step Towards High-Molecular-Weight Living/Controlled Polystyrene Using SG1-Mediated Polymerization
Résumé
The synthesis of high-molecular-weight living/controlled polystyrene by NMP was studied. The combination of Ac2O 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 autoinitiation and thus obtain high-Mn PS, the temperature was lowered. At 90°C, the use of BlocBuilder yielded PS of Mn=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 kc caused a loss of control and livingness for high-Mn polymers.