Photoinitiation of cationic polymerization. III. Photosensitization of diphenyliodonium and triphenylsulfonium salts
作者:
S. Peter Pappas,
Leslie R. Gatechair,
Josef H. Jilek,
期刊:
Journal of Polymer Science: Polymer Chemistry Edition
(WILEY Available online 1984)
卷期:
Volume 22,
issue 1
页码: 77-84
ISSN:0360-6376
年代: 1984
DOI:10.1002/pol.1984.170220108
出版商: John Wiley&Sons, Inc.
数据来源: WILEY
摘要:
AbstractPhotoinitiated cationic polymerization by photosensitization of diphenyliodonium and triphenylsulfonium salts is shown to proceed by two distinct electron transfer process: (1) direct electron transfer from excited‐state photosensitizers and (2) indirect electron transfer from photogenerated radicals. The efficiency of the former process is attributed to the instability of the reduction products (from diphenyliodonium and triphenylsulfonium salts), which dissociate in competition with undergoing energy‐wastage reverse electron transfer. Amplification of photons in the production of protons (or other reactive cations) is postulated to account for the high quantum yields observed in the latter process. Potential advantages of utilizing the indirect redox process in the design of UV curable hybrid systems, which contain functionality for both radical and cationic polymerization, are noted. The results also provide evidence against the importance of triplet states of the onium salts in photoinitiator activ
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