Light-induced polymerization reactions are frequently encountered in application areas such as UV-cured coatings and visible light cured dental materials due to the excellent spatiotemporal control and rapid polymerization. The photoinitiator and the photoinitiating system largely contribute to the extent of conversion and are therefore integral to the efficiency of the polymerization. Mixed photoinitiating systems may have the ability to increase polymerization efficiency as a result of access to extended activation wavelengths and the potential for synergistic “cross-talk” between the initiators that could result from either an energy transfer from the excited state of one photoinitiator to the ground state of a second initiator or some other mechanism that could expedite the rate of polymerization. Mixed initiating systems are also used in photocuring of orthogonal hybrid polymerizations. Current work has focused on study of the interaction between BAPO and DMPA (Irgacure 819 and Irgacure 651, respectively), two Type I photoinitiators that undergo bond cleavage upon irradiation at different wavelengths (LEDs at 365, 405, and 440nm). The recent development of a coupled UV-Vis/FT-NIR spectroscopic technique allows for the simultaneous, real-time monitoring of kinetic parameters involving both initiators and monomers. Some work has been done previously to investigate monomer conversion and the rate of polymerization, but little has been done to monitor the photoinitiator. The incorporation of UV-Vis allows for the observation of not only photoinitiator consumption, but also the formation of intermediate and decomposition products on the millisecond timescale. The photoinitiator and by-product spectral overlap and thus necessitate the use of deconvolution techniques to individually monitor the absorbance profiles.

Coupled UV-Vis/FT-NIR spectroscopy for the real-time investigation of photopolymerization kinetics using mixed photoinitiating systems

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.