Two series of homodimeric hemicyanine dyes based on 4-(p-N,N-dialkylaminostyryl)pyridinium and 4-(p-N,N-dialkylaminostyryl)quinolinium residues have been evaluated as novel photoinitiators for radical polymerization induced with an argon ion laser visible emission. In the tested photoredox pairs, hemicyanine dye cation acts as an electron acceptor and it is coupled with n-butyltriphenyl borate anion being an electron donor. The photochemistry of the series of bichromophoric stilbazolium borates, 1,3-, 1,5-, and 1,10-bis44-(p-N,N-dialkylaminostyryl)pyridinyl]alkane di-n-butyltriphenylborates and 1,3-, 1,5-, and 1,10-bis-[4-(p-N,N-dialkylaminostyryl) quinolinyl]alkane di-n-butyltriphenylborates, was compared with the photochemistry of the structurally related, monochromophoric styrylpyridinium and the styrylquinolinium borates. The experimental results indicated that the rate of photopolymerization depends on Delta G(el) of the electron transfer between borate anion and hemicyanine cation. The relationship between the rate of polymerization and the free energy of activation shows the dependence predicted by the classical theory of the electron transfer. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 118: 1395-1405, 2010