Synergistic effects of N-vinylamides in photopolymerization of simple acrylate formulations

摘要

Inhibition of free-radical polymerization processes by ambient molecular oxygen can dramatically reduce polymerization efficiency and can significantly affect the final properties of the cured product. Oxygen inhibition can be especially significant in polymerization of thin films under low intensity irradiation, or at very high production line speeds. Historically, formulators in the coatings and ink industries have used N-vinylpyrrolidinone (NVP) as a reactive diluent in formulations that cure by free-radical polymerization processes, and have observed that NVP enhances cure rates under ambient conditions in the presence of oxygen. Previously we have shown that NVP and N-vinylformamide dratmically increase the relative rate of acrylate polymerization in air at low light intensities. In the present work, we have extended the study to include other cyclic and acyclic N-vinylamides as well as N-alkylamide model compounds. Kinetic and spectroscopic studies were performed to elucidate possible explanations for the synergistic rate enhancements observed with several of the N-vinylamides in simple acrylate formulations.