Open AccessInitiators Based on Benzaldoximes: Bimolecular and Covalently Bound Systems
Author(s) -
Markus Grießer,
Arnulf Rosspeintner,
Claudia Dworak,
Michael Höfer,
Gottfried Grabner,
Robert Liska,
Georg Gescheidt
Publication year - 2012
Publication title -
macromolecules
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.994
H-Index - 313
eISSN - 1520-5835
pISSN - 0024-9297
DOI - 10.1021/ma301959n
Subject(s) - flash photolysis , radical , photochemistry , chemistry , cidnp , electron paramagnetic resonance , polymerization , radical polymerization , photopolymer , reactivity (psychology) , polymer chemistry , photoinduced electron transfer , covalent bond , photodissociation , electron transfer , polymer , kinetics , reaction rate constant , organic chemistry , medicine , physics , alternative medicine , nuclear magnetic resonance , quantum mechanics , pathology
Typical bimolecular photoinitiators (PIs) for radical polymerization of acrylates show only poor photoreactivity because of the undesired effect of back electron transfer. To overcome this limitation, PIs consisting of a benzaldoxime ester and various sensitizers based on aromatic ketones were introduced. The core of the photoinduced reactivity was established by laser flash photolysis, photo-CIDNP, and EPR experiments at short time scales. According to these results, the primarily formed iminyl radicals are not particularly active. The polymerization is predominantly initiated by C-centered radicals. Photo-DSC experiments show reactivities comparable to that of classical monomolecular type I PIs like Darocur 1173.
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