Supramolecular diaryliodonium salt‐crown ether complexes as cationic photoinitiators. Issue 4 (5th December 2012)

• Record Type: Journal Article
• Authors: Crivello, James V.; Aldersley, Michael F.
• Is Part Of: Journal of polymer science. Volume 51:Issue 4(2013:Feb.)
• Page Start: 801
• Page End: 814
• Publication Date: 2012-12-05
• Subjects: cationic polymerization -- initiators -- photopolymerization; 547
• DOI: 10.1002/pola.26452
• Languages: English
• ISSNs: 0887-624X

Abstract

Abstract: Diaryliodonium salts spontaneously form crystalline 1:1 supramolecular complexes at room temperature in good to excellent yields with 18‐crown‐6 ether and its cyclohexano‐ and benzo‐substituted analogs. The complexes were characterized using IR, UV, MS, 1 H, and 13 C‐NMR spectroscopy and by single crystal X‐ray crystallography. The analytical data obtained were consistent with a structure in which the positively charged iodine atom of diaryliodonium cation is positioned above and over the center of the crown ether ring with the positively charged iodine atom coordinated to the crown ether oxygen atoms. The diaryliodonium salt‐crown ether complexes are photosensitive and were used to carry out the photoinitiated cationic polymerizations of a number of mono‐ and difunctional monomers. During irradiation with UV light, the supramolecular complexes undergo photolysis with the generation of a Brønsted acid and with the concomitant release of the crown ether. When used as photoinitiators, the crown ether that is released markedly influences the kinetics of the subsequent cationic polymerization of the monomer. Further studies demonstrated that the photolysis of diaryliodonium salt‐crown ether supramolecular complexes can be photosensitized using typical‐electron transfer photosensitizers. Free radical‐promoted photosensitization using typical unimolecular free radical photoinitiators such as 2, 2‐dimethoxy‐2‐phenylacetophenone also takes place readily. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013 Abstract : Crystalline 1:1 supramolecular complexes of diaryliodonium salts 18‐crown‐6 ether and its analogs are photosensitive and were used as photoinitiators to carry out the cationic polymerizations of a number of mono‐ and difunctional monomers. The crown ether that is released on photolysis markedly influences the kinetics of the subsequent cationic polymerization of the monomer by complexing with the photogenerated acid.