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LED‐Induced Polymerization (385, 405, and 455 nm) Using Star‐Shaped Tris(4‐(thiophen‐2‐yl)phenyl)amine Derivatives as Light‐Harvesting Photoinitiators
Author(s) -
Zhang Jing,
Sallenave Xavier,
Bui ThanhTuan,
Dumur Frédéric,
Xiao Pu,
Graff Bernadette,
Gigmes Didier,
Fouassier Jean Pierre,
Lalevée Jacques
Publication year - 2015
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.201400403
Subject(s) - photochemistry , photopolymer , amine gas treating , polymerization , chemistry , flash photolysis , polymer chemistry , cationic polymerization , methyl methacrylate , carbazole , materials science , polymer , organic chemistry , kinetics , physics , quantum mechanics , reaction rate constant
Two star‐shaped tris(4‐(thiophen‐2‐yl)phenyl)amine derivatives, namely tris(4‐(5‐(3‐pentylthieno[3,2‐ b ]thiophen‐5‐yl)thiophen‐2‐yl)phenyl)amine and tris(4‐(5‐(3‐pentyl‐2‐(thiophen‐2‐yl)thieno[3,2‐ b ]thiophen‐5‐yl)thiophen‐2‐yl)phenyl)amine, are developed as photoinitiators for radical and cationic polymerizations under near‐UV and visible light‐emitting diodes (LEDs) (e.g., 385, 405, and 455 nm). When used in combination with an iodonium salt (and optionally N ‐vinyl carbazole) or an amine/alkyl halide couples, they lead to excellent photoinitiating abilities for the polymerization of epoxides or (meth)acrylates under air. Compared with commercial photoinitiators, i.e., camphorquinone‐based systems or bis(2,4,6‐trimethylbenzoyl)‐phenylphosphineoxide, the novel photoinitiators exhibit noticeably higher polymerization efficiencies under air (epoxide conversions = 41–57% vs ≈0%, halogen lamp exposure; methacrylate conversions = 50–55% vs 44%, LED at 405 nm exposure; methacrylate conversions = 34–42% vs 0–8%, LED at 455 nm exposure). These systems are also interesting in overcoming oxygen inhibition. The photochemical mechanisms are studied by steady‐state photolysis, electron spin resonance spin trapping, fluorescence, cyclic voltammetry, and laser flash photolysis techniques.