TEMPERATURE-SENSITIVE LUMINESCENCE OF TRIS(BETA-DIKETONE) EUROPIUM CHELATES FOR MONITORING HIGH-SPEED CATIONIC PHOTOPOLYMERIZATIONS

The temperature-dependent luminescence of tris(beta-diketone) chelates of europium was used for in situ temperature measurements during cati onic photopolymerizations of vinyl ethers. These molecular-level lumin escent probes provided a real-time, noninvasive method for monitoring temperature during these high-speed polymerizations.: Two specific pro bes, tris(benzoyl-1,1,1-trifluoroacetone) europium and tris(1,1,1,5,5, 5-hexafluoroacetylacetone) europium, met several stringent spectral an d performance requirements for application in our system. The luminesc ence from these probes exhibits a reproducible temperature dependence over a wide temperature range and is not sensitive to changes in visco sity. In situ temperature profiles obtained using this novel technique verified the importance of thermal effects during these highly exothe rmic photopolymerizations. These studies have demonstrated the utility of the tris(beta-diketone) europium chelates for characterizing the t emperature during high-speed photopolymerizations that cannot be monit ored using conventional techniques. (C) 1995 John Wiley and Sons, Inc.