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Time‐Resolved Electron Spin Resonance Spectroscopy of Radicals Formed During Free Radical Polymerizations of Alkyl Acrylates
Author(s) -
Kajiwara Atsushi
Publication year - 2009
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200900606
Subject(s) - radical , electron paramagnetic resonance , chemistry , radical polymerization , reaction rate constant , photopolymer , photochemistry , polymerization , acrylate , alkyl , monomer , acrylate polymer , spectroscopy , kinetics , polymer chemistry , polymer , nuclear magnetic resonance , organic chemistry , physics , quantum mechanics
Time‐resolved electron spin resonance (TR ESR) spectra allows direct observation of transient radicals (primary propagating radicals) obtained by the addition reaction of a diphenylphosphinoyl radical to acrylates. The addition rate constants ( k 2 ) of the diphenylphosphinoyl radical to the acrylates (initiation rate constants) were determined by the monomer concentration dependence of the decay rate of the diphenylphosphinoyl radical. The value of k 2 was 1.9 × 10 7 s −1 · M −1 for the case of t ‐butyl acrylate, while the k 2 values of ethyl, n ‐butyl, 2‐ethylhexyl, and dodecyl acrylates were about 1 × 10 7 s −1 · M −1 . A combination of steady state ESR and TR ESR provided information on the kinetics both of initiation and propagation processes in the radical polymerization of acrylates.