Zero-valent metal catalyzed removal of thiocarbonylthio end groups from RAFT-made polystyrene: producing controllable bimodal molecular weight distribution

Abstract

This work presents a facile method for removing thiocarbonylthio end groups from RAFT-made polystyrene (PS) under the catalysis of Cu(0) or Fe(0). In Cu(0)-catalyzed cases, 2,2,6,6-tetramethylpiperidinyl-1-oxy (TEMPO) was able to promote the removal of thiocarbonylthio end groups with the production of a distinct bimodal molecular weight distribution (MWD). The chain end structure of the resultant polymer was carefully identified by the matrix-assisted laser desorption ionization time-of-flight mass spectrum. However, in the Fe(0)-catalyzed system, TEMPO and ligands were not needed for the removal of thiocarbonylthio end groups with a more efficient removal. This work provides an alternative approach for removing thiocarbonylthio end groups of RAFT-made PS as well as producing thiocarbonylthio-free PS with controllable bimodal MWD.