IONIC PHOTOINITIATORS FOR RADICAL POLYMERIZATION IN DIRECT MICELLES - THE ROLE OF THE EXCITED-STATES

Radical photopolymerization reactions of MMA in direct anionic and cationic micelles are investigated in the presence of different types of ionic initiators, through steady state illumination experiments and time-resolved laser spectroscopy. The positively charged ionic photoinitiator BP** plus appears as the more efficient. The reactivity of the excited states involved as well as the behavior of the side radicals produced seem to govern for a large part the practical efficiency of these compounds. A general discussion on the role of the different factors (localization, electronic effects, monomer quenching, electron and proton transfer processes, radical exit from the micelle, and acid-base equilibrium) is presented.