Electron-transfer reactions in cyanine borate ion pairs: photopolymerization initiators sensitive to visible light
Photoinitiation of polymerization is a process of immense practical, economic, and theoretical importance. In typical examples the polymerization of an acrylate or styrene-derived monomer is initiated by irradiation of a sensitizer with ultraviolet light. The excited state of the sensitizer may dissociate directly to form active free radicals as in the case of the benzoin ethers, or it may first undergo a bimolecular electron-transfer reaction whose products initiate polymerization as is the case in the benzophenone-dimethylaniline system. Efforts to extend the range of useful photoinitiators of free-radical polymerization to the visible region of the spectrum have heretofore met with only modest success. These special initiators typically are sensitive only to blue light or suffer from thermal instability and have low quantum efficiencies. The authors report herein the discovery that triphenylalkylborate salts of cyanine dyes (Chart I) are photoinitiators of free-radical polymerization whose sensitivity throughout the entire visible spectral region is the result of a novel intra-ion-pair electron-transfer reaction.
- Research Organization:
- Univ. of Illinois, Urbana (USA)
- OSTI ID:
- 7159734
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:7
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BORATES
CATALYTIC EFFECTS
CYANINE DYES
RADICALS
PHOTOCHEMICAL REACTIONS
POLYMERIZATION
ABSORPTION SPECTROSCOPY
CATALYSIS
CATALYSTS
ELECTRON TRANSFER
EXPERIMENTAL DATA
PHOTOCHEMISTRY
BORON COMPOUNDS
CHEMICAL REACTIONS
CHEMISTRY
DATA
DYES
INFORMATION
NUMERICAL DATA
OXYGEN COMPOUNDS
SPECTROSCOPY
400500* - Photochemistry