Synthesis of Novel Macrophotoinitiator for the Photopolymerization of Acrylate

A new kind of macrophotoinitiator (MPI) was synthesized through the copolymerization of acrylic monomers and the polymerizable photoinitiator monomer 2959-AA. Monomer 2959-AA was obtained by an esterification reaction between acrylic acid (AA) and the water-soluble photoinitiator Irgacure 2959 [2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone]. By adjusting the monomer proportions in the MPIs, two series of MPIs with different 2959-AA contents and different glass transition temperatures were obtained. The molecular structure of 2959-AA was characterized by Fourier-transform infrared spectroscopy, nuclear magnetic spectrometry, and mass spectrometry. Polymerization of 1, 6-hexanediol diacrylate was initiated using Irgacure 2959 and 2959-AA, and two series of MPIs to be polymerized were studied with a photo-DSC test. Results showed that 2959-AA had higher chemical reactivity than Irgacure 2959 because of the higher solubility of the former. It was evident from the experiments that 2959-AA content in the MPI progressively increased the polymerization rate and monomer conversion when the glass transition temperatures of MPIs were similar. At the same 2959-AA content, the polymerization rate slightly slowed down with increased glass transition temperature. However, the radical lifetime and polymerization time were prolonged. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40352.