Acceleration of the free radical polymerization by using N-alkoxypyridinium salt as co-initiator in hemicyanine dye/borate salt photoinitiating system

Results of kinetic studies of the two-component and three-component photoinitiator system used in visible-light photoinduced polymerization of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol (TMPTA) are presented. Five different hemicyanine dyes ((6-bromo-3-ethyl-2-(p-alkylamino)styryl) benzothiazolium salts SBr) were used as sensitizers in photoinitiator systems, with four different co-initiators. The rates of polymerization were compared with the rate of polymerization photoinitiated by well known photoinitiator composed of hemicyanine dye and n-butyltriphenylborate anion as co-initiator. Reactive radicals that initiate the polymerization are formed by a mechanism of photoinduced electron transfer process and are different for all co-initiators tested.In this paper we shown that photoinitiator system composed of sensitizer and co-initiator is less efficient to the photoinitiation of free radical polymerization of TMPTA than photoinitiator system possessing dye as sensitizer and two types of co-initiators.