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Investigation of Barton esters as radical photoinitiators
Author(s) -
Dietlin C.,
Allonas X.,
MorletSavary F.,
Fouassier J. P.,
Visconti M.,
Norcini G.,
Romagnano S.
Publication year - 2008
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.26618
Subject(s) - radical , chemistry , photochemistry , thiazole , polymerization , photopolymer , monomer , pyridine , singlet state , excited state , alkyl , radical polymerization , polymer chemistry , spectroscopy , organic chemistry , polymer , physics , quantum mechanics , nuclear physics
Different photoinitiators based on Barton thiohydroxamic esters, O ‐acyl‐ N ‐hydroxy‐pyridine‐2(1H)‐thione and O ‐acyl‐ N ‐hydroxy‐thiazole‐2(3H)‐thione derivatives, were tested in photopolymerization reactions through time‐resolved FTIR spectroscopy. Good rates of polymerization and final monomer conversion were obtained for some compounds. The excited state processes, investigated by time resolved absorption spectroscopy, lie on a fast singlet state cleavage leading to thiyl and alkyl radicals. Both the pyridine‐2(1H)‐thiyl and alkyl radicals are able to initiate a polymerization, in contrast with the thiazole‐2(3H)‐thiyl radical. A triplet state is observed for some derivatives. Computational studies help to describe the excited state properties and show a strong difference in the spin localization in the formed thiyl initiating radicals. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008