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EPR/ENDOR study of the decay of trapped radicals in photopolymerized butane‐1,4‐diol diacrylate
Author(s) -
Oliva Cesare,
Selli Elena,
Ponti Alessandro,
Bellobono Ignazio Renato,
Morelli Roberto
Publication year - 1992
Publication title -
journal of physical organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.325
H-Index - 66
eISSN - 1099-1395
pISSN - 0894-3230
DOI - 10.1002/poc.610050108
Subject(s) - electron paramagnetic resonance , radical , chemistry , hyperfine structure , butane , photochemistry , spectroscopy , nitroxide mediated radical polymerization , nuclear magnetic resonance , analytical chemistry (journal) , atomic physics , polymer , polymerization , radical polymerization , organic chemistry , quantum mechanics , catalysis , physics
Long‐lived trapped radicals produced during the photopolymerization of butane‐1, 4‐diol diacrylate (BDDA) were studied by EPR and ENDOR spectroscopy and their thermal decay was followed by EPR measurements at different temperatures (40–120 °C) for kinetic study. The EPR signal showed the superimposition of two different patterns, a three‐line and a single‐line spectrum. Both EPR patterns decayed following first‐order kinetics in the investigated temperature range. Activation parameters of the decay were obtained. The EPR patterns were attributed to the same radical species situated in fluid and in cross‐linked regions of the photopolymerized BDDA. Radicals of the latter kind undergo electron spin exchange strong enough to wash out the hyperfine splitting. The single‐line width is mainly determined by electron spin dipole–dipole interactions. The ENDOR response is only of the matrix kind, typical of radicals in a solid phase. The present model was also compared with recent literature reports.