Visible light pulsed-laser polymerization at 532 nm employing a julolidine dye photosensitizer initiation system

The free-radical propagation rate coefficient of methyl methacrylate has been measured using a new version of pulsed-laser polymerization employing a visible light wavelength (532 nm) generated by a frequency-doubled Nd:YAG laser. The initiation system adopted was made up from 2,2′-bis(2-chlorophenyl)-4,4′,5,5′-tetraphenyl-1,2′- biimidazole), mercaptobenzoxazole, and 2,5-bis[(1H,5H-benzo[i,j]quinolizin-1-yl)methylene]cyclopentanone. The propagation rate coefficients obtained were consistent with values recommended as benchmark values by an IUPAC working party. A series of consistency checks was performed to ensure the validity of the experimental approach. The experimental technique described in this paper extends the pulsed-laser polymerization method to a whole new range of UV-absorbing monomers that were previously inaccessible to study.