Search

Two benzotriazole derivatives, 2-benzyl-4,7-di(thiophen-2-yl)-2H-benzo[d][1,2,3]triazole (BBTS) and 2-benzyl-4,7-bis(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-2H-benzo[d] [1,2,3]triazole (BBTES) were employed as photosensitizers for diaryliodonium salt photoinitiators in photoinitiated cationic polymerization of various epoxide and vinyl ether monomers. Diphenyliodonium hexafluorophosphate (Ph2I+PF6 –) salt was used as the photoinitiator in this study. Extended conjugation and electron-rich moieties of the photosensitizers enabled the use of long wavelength UV and visible light emitting light sources in cationic photopolymerizations. Having low oxidation potentials and good solubility in cationically polymerizable monomers make them efficient photosensitizers for the diphenyliodonium salt in the photoinitiated cationic polymerization. Polymerizations were achieved at room temperature and monitored by optical pyrometry. Moreover, photopolymerization of a diepoxide monomer with ambient solar irradiation in the presence of BBTES and BBTS were examined. [ABSTRACT FROM AUTHOR]

Abstract: The present paper is focused on visible light initiated cationic polymerizations. Photoinitiated polymerization of representative vinyl ether and oxirane monomers using two quinoxaline derivatives; namely (2-(2,3-dihydrobenzo [b][1,4]dioxin-6-yl)-3-(2,3-dihydrobenzo[b]-[1,4]dioxin-7-yl)-5-(2,3-dihydrothieno[3,4-b][1,4]dioxin-5-yl)-8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-7yl) quinoxaline) (DBQEd) and 2,3,5,8-tetra(thiophen-2-yl)quinoxaline (TTQ) are studied. Novel dyes based on the quinoxaline skeleton are employed as efficient photosensitizers in cationic photopolymerizations. Polymerizations were initiated at room temperature upon irradiation with long-wavelength UV and visible lights in the presence of diphenyliodonium hexafluorophosphate (Ph2I+PF6 −). The progress of the polymerizations was monitored by optical pyrometry (OP). Solar irradiation is also employed to carry out the cationic polymerization of a diepoxide monomer in the presence of air. [Copyright &y& Elsevier]

Abstract: This article describes the use of functionalized quinoxaline derivatives as photosensitizers for diaryliodonium salt photoinitiators. Highly conjugated compounds with good absorption bands in long wavelength UV and visible region are presented. These versatile intermediates facilitate photoinitiated cationic polymerization of commercially important monomers such as cyclic ethers and vinyl epoxides. Polymerizations were carried out using long wavelength UV light in the presence of diphenyliodonium hexafluorophosphate ( ). The polymerizations were monitored by optical pyrometry (OP). In addition, we also demonstrate that it was also possible to initiate photopolymerizations under solar irradiation in the presence of these photosensitizers. [Copyright &y& Elsevier]