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Visible light photopolymerization in BHDC reverse micelles. Laser flash photolysis study of the photoinitiating mechanism

Paper ID Volume ID Publish Year Pages File Format Full-Text
27093 44000 2013 6 PDF Available
Title
Visible light photopolymerization in BHDC reverse micelles. Laser flash photolysis study of the photoinitiating mechanism
Abstract

The photopolymerization of acrylamide (AA) in reverse micelles (RMs) of benzyl hexadecyl dimethylammonium chloride (BHDC) was investigated. The polymerization was performed by irradiation in the 500 nm region of the spectrum, employing as photoinitiating system the synthetic dye safranine-O and triethanolamine (TEOA) as co-initiator. The characterization of the nanoparticles of polyacrylamide was done by dynamic light scattering. Molecular weight determinations were carried out by viscosimetry. Small nanoparticles of polyacrylamide are formed with a low polydispersity and a molecular weight close to 106. The results were compared with those in AOT (sodium bis(2-ethylhexyl) sulfosuccinate) RMs. Laser flash photolysis was used to investigate the photoinitiating mechanism. The maximum of the T–T absorption spectra in RMs confirms that, in spite of its positive charge, the dyes remain at the interface co-micellizing with BHDC. The triplet lifetime is much longer in the RMs than in homogeneous organic solvents. The triplet quenching by TEOA was very much more effective in the RMs than in a homogeneous solvent. The quantum yield of formation of active radicals was evaluated from the transient absorption spectra. It was concluded that they are generated by an intermicellar electron transfer process followed by an intramicellar proton transfer reaction. The quantum yield was found to be 0.2 ± 0.02. A similar radical yield in a homogeneous solvent requires an amine concentration near 50 times higher.

► The photopolymerization of acrylamide in reverse micelles of benzyl hexadecyl dimethylammonium chloride (BHDC) was investigated. ► The polymerization was initiated with light >500 nm using the synthetic dye safranine-O as sensitizer and triethanolamine as co-initiator. ► The polymerization proceeds efficiently with a co-initiator concentration much lower than in homogeneous solvents. ► The polymer nanoparticles were highly monodisperse. ► Laser flash photolysis was employed to investigate the photochemistry of the photoinitiating system in the reverse micelles.

Keywords
Visible photopolymerization; Safranine; Microemulsion polymerization; Reverse micelles; Triplet quenching
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Visible light photopolymerization in BHDC reverse micelles. Laser flash photolysis study of the photoinitiating mechanism
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Photochemistry and Photobiology A: Chemistry - Volume 257, 1 April 2013, Pages 60–65
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us