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Competitive Equilibria in Atom Transfer Radical Polymerization
Author(s) -
Tsarevsky Nicolay V.,
Braunecker Wade A.,
Vacca Alberto,
Gans Peter,
Matyjaszewski Krzysztof
Publication year - 2007
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200750207
Subject(s) - chemistry , catalysis , disproportionation , atom transfer radical polymerization , photochemistry , dissociation (chemistry) , polymer chemistry , radical polymerization , cobalt mediated radical polymerization , polymerization , polymer , organic chemistry
Abstract With the recent development of new initiation techniques in atom transfer radical polymerization (ATRP) that allow catalysts to be employed at unprecedented low concentrations (∼10 ppm), a thorough understanding of competitive equilibria that can affect catalyst performance is becoming increasingly important. Such mechanistic considerations are discussed herein, including i) factors affecting the position of the ATRP equilibrium; ii) dissociation of the ATRP catalyst at high dilution and loss of deactivator due to halide dissociation; iii) conditional stability constants as related to competitive monomer, solvent, and reducing agent complexation as well as ligand selection with respect to protonation in acidic media; and iv) competitive equilibria involving electron transfer reactions, including the radical oxidation to carbocations or reduction to carbanions, radical coordination to the metal catalyst, and disproportionation of the Cu I ‐based ATRP activator.