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	Photocatalysis of viologens for photoinitiated polymerization using carboxylic acid as electron donors
	Cao, Liangcheng1; Wang, Yuechuan2
	2017-01-15
摘要	Hydroxyl radicals (*OH), together with carbon-centered radicals (*R), derived from photoinduced electron transfer (PET) interactions between viologen and carboxylic acid ion pairs ([bipy(++) . . .RCOOH]) ), were developed to photoinitiate the polymerization of various acrylate monomers in the presence of oxygen. The mechanism of the radicals' formation was established using nanosecond laser flash photolysis and electron spin resonance methods. Carboxylate anion (electron donnor, D) gave one electron to viologen (electron acceptor, A) via either intermolecule (D/A) or intramolecular (D-A) PET, to yield carboxylate radicals (RCOO*) that later underwent decarboxylation, yielding *R radicals which can initiate the photopolymerization of many acrylate monomers. Simultaneously, reduced viologen cation radical (bipy(+*)) was oxidized by dissolved O-2 and returned back to bipy(++) dications. *OH radicals emerged from the reaction of H+ with the superoxide radicals (O-2*(-)) that formed during the oxidation of In this way, viologens were observed to act as photocatalysts in the radical generation process based on their strong electron acceptor, as well as efficient light absorption nature. Photopolymerization performance with D-A type viologens, for instance, bipy(++)-(CH2)(n)COOH, extra carboxylic acid was not a requirement. (C) 2016 Elsevier B.V. All rights reserved.
关键词	Viologen Photocatalysis Electron transfer Photopolymerization
DOI	10.1016/j.jphotochem.2016.10.019
发表期刊	JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY A-CHEMISTRY
ISSN	1010-6030
卷号	333页码:63-69
通讯作者	Cao, LC (reprint author), Chinese Acad Sci, Chongqing Inst Green & Intelligent Technol, Fangzheng Ave 266, Chongqing 400714, Peoples R China.
收录类别	SCI
WOS记录号	WOS:000389393100008
语种	英语