Three-component photoinitiator systems typically contain a light absorbing molecule (the dye), and electron donor (typically an amine) and a third component (usually an iodonium salt). These systems have consistently been found to be faster, more efficient, and more sensitive than the traditional single-component a-cleavable initiators or the two-component electron transfer systems. Moreover, since a wide variety of dyes may be used, the three-component initiator systems are extremely flexible in selection of the initiating wavelength. Finally, with proper selection of the components the same initiating systems may be effective for initiation of cationic polymerizations as well as radical polymerizations.

     Objective: to provide a fundamental characterization of the kinetics and mechanisms of selected three component systems and to identify general underlying principles that will guide the design and selection of initiator systems based upon the desired initiating wavelength, light sensitivity, and polymerization rate. The knowledge gained in this research should allow the development of initiator systems which optimize the polymerization rate for a given light source by managing the absorption of light and the production of active centers through primary photochemical reactions and secondary reactions.