One photon–two radical-electron transfer photoinitiators. 2-( o-, m-, or p-Methoxypyridine)- p-pyrrolidinestyrilium methyl sulfates as photoinitiators of free radical polymerization

In this paper, the novel hemicyanine dye–borate pair, e.g. 2-(( o, m, or p)-methoxypyridine)- p-pyrrolidinestyrilium methyl sulfates (MeOSp)–tetramethylammonium n-butyltriphenyl borate (TBAB) were evaluated and employed as the photoinitiating pairs of multiacrylate monomer polymerization. The kinetic studies clearly demonstrate that the modification of the dye structure by the exchange of the N-alkyl group on N-alkoxy one in pyridinium moiety causes a marked increase in the efficiency of photoinitiation of 2-ethyl-2-(hydroxymethyl)-1,3-propanediol triacrylate (TMPTA) polymerization.