In situ Raman spectroscopy for cure monitoring of cationic photopolymerizations of divinyl ethers

Cationic photopolymerizations of divinyl ethers photosensitized by anthracene was studied using in situ Raman spectroscopy. With careful experimental design, Raman spectroscopy was found to provide a sensitive and convenient method for studying the photopolymerization kinetics even though one of the reactants (the photosensitizer) is highly fluorescent. in illustrative experiments, reaction profiles of the double bond conversion vs, time were obtained by monitoring the Raman peaks at 1322 and 1622 cm(-1) arising from the vinyl ether functionality. Similar reaction profiles were obtained using either of these peaks, whereas the intensity of a Raman signal at 1458 cm(-1) arising from an unreactive ethyl ether functionality, was found to be independent of conversion. The final limiting conversion was found to increase with increasing reaction temperature with values ranging from 60 to 90%. As expected, the reaction rate was determined to be very dependent on both the initiation light intensity and the temperature of the reaction.