Cationic Photopolymerization of Epoxides by Direct and Sensitized Photolysis of Onium Tetrakis(pentafluorophenyl)borate Initiators

Abstract

Cationic photopolymerization of epoxides by the direct and sensitized photolysis of eight onium tetrakis(pentafluorophenyl)borates as initiators has been investigated. The relative reactivity of the onium borates on the photopolymerization was studied by the measurement of spectral sensitivity and by real time Fourier transform infrared spectroscopy. The kinetics of the photopolymerization by the sensitized photolysis was different from that of the direct photolysis. Several onium borates were sensitized by the excited singlet state of the anthracenes (nonsubstituted anthracene and 9-methyl- and 9,10-dimethylanthracene), and the rates of polymerization increased with decreasing free energy changes between the onium borates and the excited singlet state of 9-methylanthracene. The acid generated by the photodecomposition of the onium borates produced nonacidic products by heating.

NIR-Sensitized Photopolymerization with Iodonium Salts Bearing Weak Coordinating Anions

“…29, No. 4, 2016 The iodonium salt 1, known as Rhodorsil, works well as cationic initiator for photoinitiated curing of epoxies using UV radiation [12]. This salt has a high molecular weight (M = 1016 g•mol -1 ).…”

Anthracene-sensitized polymerization of vinyl ethers by onium tetrakis(pentafluorophenyl)borate initiators

“…Anthracene was used as a sensitizer and can be sensitizing the onium borates. 7 IBVE was used as a monomer because its polymeriza- tion is well known. 14 -17 Irradiation was carried out using the light of a wavelength above 350 nm.…”

“…4 -7 In recent articles, we reported that some of the onium borates can be sensitized by anthracene and initiate photopolymerization of an epoxide. 6,7 However, polymerization rates of epoxy compounds are essentially lower than that of radical polymerizable compounds such as acrylates. On the other hand, vinyl ethers have relatively high reactivity in cationic polymerization and are not inhibited by atmospheric oxygen.…”

“…The reactivity of the onium borates as cationic initiators for the vinyl ethers is compared with the corresponding onium salts with a different anion. phenyl)methylsulfonium tetrakis(pentafluorophenyl)-borate (SFB5), 7 diphenyliodonium butyltriphenylborate (IB), 8 dimethylphenacylsulfonium butyltriphenylborate (SB), 8 and dimethylphenacylsulfonium hexafluorophosphate (SS1) 9 were prepared according to the reported procedure.…”

A study of the elemental reactions involved in the initiation of the polymerization of tetrahydrofuran induced by the photosensitization of a triphenylsulphonium salt by perylene

“…There is growing interest in polymerizations initiated by external stimulation, such as photoirradiation or highenergy radiation, 1 and much effort has been devoted to develop systems that may initiate the polymerization processes through cationic 2,3,4 and radical mechanisms. 5,6 Cationic polymerization is widely applicable for both vinyl and ring-opening polymerizations giving place to many studies of both academic and industrial interests.…”