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The importance of exchange reactions in controlled/living radical polymerization in the presence of alkoxyamines and transition metals
Author(s) -
Matyjaszewski Krzysztof
Publication year - 1996
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.19961110107
Subject(s) - radical , chemistry , polymerization , styrene , atom transfer radical polymerization , radical polymerization , living free radical polymerization , photochemistry , nitroxide mediated radical polymerization , polymer chemistry , cobalt mediated radical polymerization , reaction rate constant , living polymerization , polymer , kinetics , copolymer , organic chemistry , physics , quantum mechanics
The role of exchange reactions in controlled/living radical polymerizations is analyzed. Styrene polymerization in the presence TEMPO and atom transfer radical polymerization (ATRP) catalyzed by transition metals (Cu II X 2 /2Bipy complex) are compared. ATRP proceeds approximately one order of magnitude faster than TEMPO‐moderated polymerization due to a higher stationary concentration of radicals and an equilibrium more shifted to the side of radicals. ATRP can provide better defined polymers with polydispersities down to M w /M n ≈1.05. This fact can be ascribed to a faster deactivation process and a smaller contribution of side reactions. The polydispersities in both systems are defined by the relative rates of the deactivation and propagation processes. The rate constant of deactivation of growing polystyryl radicals by TEMPO is in the range of k d ≈10 8 mol −1 ·L·s −1 , which is substantially higher than the previously reported value.