Zero-valent metal catalyzed radical-induced adjustable removal/modification of thiocarbonylthio end groups of RAFT polymer at ambient temperature†

Xiaofei Zhang^a,Wenxiang Wang^a,Kai Guo^b,Chrys Wesdemiotis^bc,Zhengbiao Zhang*^a(张正彪) and Xiulin Zhu*^a(朱秀林)

^aJiangsu Key Laboratory of Advanced Functional Polymer Design and Application, Department of Polymer Science and Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China.^bDepartment of Polymer Science, The University of Akron, Akron, Ohio 44325, USA.^cDepartment of Chemistry, The University of Akron, Akron, Ohio 44325, USA

Polym. Chem.2013,4, 637-644.

This work describes a facile removal/modification of thiocarbonylthio end groups of RAFT-made polymers by the utilization of zero-valent copper (Cu(0)) powder/2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) under mild conditions, especially for poly(methyl methacrylate) (PMMA). At [PMMA]₀/[Cu(0)]₀/[ligand]₀/[TEMPO]₀= 1/5/5/1.5, the molecular weights (MWs) gradually increased to twofold that of the precursor, due to the polymeric radical–polymeric radical cross coupling. While the MW remained unchanged at [PMMA]₀/[Cu(0)]₀/[ligand]₀/[TEMPO]₀= 1/5/5/5, generating vinyl group terminated telechelic polymersviaa polymeric radical–TEMPO disproportionation process. The utilization of Cu(0) wire can also remove the thiocarbonylthio end group effectively. Zero-valent iron (Fe(0)) (powder or wire) can be applied to remove/modify the thiocarbonylthio end group instead of Cu(0)/ligand with comparable results. This work provided an alternative and promising approach for an adjustable end group removal/modification of RAFT polymers, and would eventually strengthen and facilitate the potential large-scale application of RAFT-related polymers.

链接：http://pubs.rsc.org/en/content/articlelanding/2012/PY/C2PY20667F#!divAbstract