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Photopolymerization and initiating mechanism of Michael addition oligomers without photoinitiator
Author(s) -
Zhang Xiahong,
Yang Jianwen,
Zeng Zhaohua,
Wu Yuanwei,
Huang Liang,
Chen Yonglie,
Wang Haihua
Publication year - 2007
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20787
Subject(s) - photoinitiator , photopolymer , polymer chemistry , materials science , acrylate polymer , moiety , trimethylolpropane , acrylate , polymerization , diketone , methacrylate , acetylacetone , ethyl acrylate , photochemistry , copolymer , chemistry , organic chemistry , polymer , monomer , composite material , polyurethane
A series of acrylic oligomer which can undergo self‐initiation under UV irradiation were synthesized by Michael addition of acetylacetone (acac) with multi‐functional acrylates using diazabicycloundecene as catalyst. GC‐MS and proton NMR were employed to study the photolysis mechanism of model molecule which was prepared from acac and ethyl acrylate. The β‐diketone moiety attached to a fully substituted carbon atom was photoscissile and prone to produce alkyl free radicals by losing acetyl free radical. Polymerization of the acrylated β‐diketone‐containing oligomers can be thus efficiently triggered regardless of solely irradiated under UV light or blended with pure trimethylolpropane triacrylate. As determined with photo‐DSC, the acrylated β‐diketone‐containing oligomers photopolymerized more slowly than the traditional system of trimethylolpropane triacrylate containing Darocur 1173 at the early stage, but reached a higher final conversion. The rheology measurement showed that the synthesized acrylated β‐diketone‐containing oligomers exhibited shear thinning property. POLYM. ENG. SCI., 47:1082–1090, 2007. © 2007 Society of Plastics Engineers