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EPR Analysis of n ‐Butyl Acrylate Radical Polymerization
Author(s) -
Barth Johannes,
Buback Michael,
Hesse Pascal,
Sergeeva Tatiana
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.200900531
Subject(s) - electron paramagnetic resonance , radical , polymerization , monomer , acrylate , polymer chemistry , radical polymerization , chemistry , butyl acrylate , photochemistry , materials science , polymer , nuclear magnetic resonance , organic chemistry , physics
Via electron paramagnetic resonance (EPR) spectroscopy, concentrations of secondary propagating radicals (SPRs) and tertiary mid‐chain radicals (MCRs) in n ‐butyl acrylate solution polymerization were measured. The EPR spectrum is dominated by the 4‐line spectrum of SPRs at −50 °C and by the 7‐line spectrum of MCRs at +70 °C. At intermediate temperatures, a third spectral component is seen, which is assigned to an MCR species with restricted rotational mobility. The MCR components are produced by 1,5‐hydrogen shift (backbiting) of SPRs. The measured ratio of MCRs to SPRs allows for estimating the rate coefficient k p tfor monomer addition to a mid‐chain radical. For 70 °C, k p tis obtained to be 65.5 L · mol −1 · s −1 .