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1596524 
Journal Article 
Visible Light Induced Free Radical Promoted Cationic Polymerization Using Thioxanthone Derivatives 
Yilmaz, G; Beyazit, S; Yagci, Y 
2011 
Yes 
Journal of Polymer Science. Part A, Polymer Chemistry
ISSN: 0887-624X
EISSN: 1099-0518 
49 
7 
1591-1596 
English 
WOS:000288517400009 
The free radical promoted cationic polymerization
cyclohexene oxide (CHO), was achieved by visible light irradiation (lambda(inc) 430-490 nm) of
methylene chloride solutions containing thioxanthone-fluorene carboxylic acid (TX-FLCOOH) or
thioxanthone-carbazole (TX-C) and cationic salts, such as diphenyliodonium hexafluorophosphate
(Ph(2)I(+)PF(6)(-)) or silver hexafluorophosphate (Ag(+)PF(6)(-)) in the presence of hydrogen
donors. A feasible initiation mechanism involves the photogeneration of ketyl radicals by
hydrogen abstraction in the first step. Subsequent oxidation of ketyl radicals by the oxidizing
salts yields Bronsted acids capable of initiating the polymerization of CHO. In agreement with
the proposed mechanism, the polymerization was completely inhibited by 2,2,6,6-
tetramethylpiperidinyl-1-oxy and di-2,6-di-tert-butylpyridine as radical and acid scavengers,
respectively. Additionally polymerization efficiency was directly related to the reduction
potential of the cationic salts, that is, Ag(vertical bar)PF(6)(-)(E(1/2) = +0.8 V) was found to
be more efficient than Ph(2)I(+)PF(6)(-)(E(red)(1/2) = -0.2 V). In addition to CHO, vinyl
monomers such as isobutyl vinyl ether and N-vinyl carbazole, and a bisepoxide such as 3,4-
epoxycyclohexyl-3',4'-epoxycyclohexene carboxylate, were polymerized in the presence of TX-
FLCOOH or TX-C and iodonium salt with high efficiency. (C) 2011 Wiley Periodicals, Inc. J Polym
Sci Part A: Polym Chem 49: 1591-1596, 2011 
cationic polymerization; oxidation; photochemistry; photoinitiator; photopolymerization; thioxanthone