IN-SITU RAMAN-SPECTROSCOPY FOR CURE MONITORING OF CATIONIC PHOTOPOLYMERIZATIONS OF DIVINYL ETHERS

Cationic photopolymerizations of divinyl ethers photosensitized by ant hracene was studied using in situ Raman spectroscopy. With careful exp erimental design, Raman spectroscopy was found to provide a sensitive and convenient method for studying the photopolymerization kinetics ev en though one of the reactants (the photosensitizer) is highly fluores cent. in illustrative experiments, reaction profiles of the double bon d conversion vs, time were obtained by monitoring the Raman peaks at 1 322 and 1622 cm(-1) arising from the vinyl ether functionality. Simila r reaction profiles were obtained using either of these peaks, whereas the intensity of a Raman signal at 1458 cm(-1) arising from an unreac tive ethyl ether functionality, was found to be independent of convers ion. The final limiting conversion was found to increase with increasi ng reaction temperature with values ranging from 60 to 90%. As expecte d, the reaction rate was determined to be very dependent on both the i nitiation light intensity and the temperature of the reaction.