Dye-sensitized photolysis of o-Cl-hexaarylbiimidazole and photopolymerization kinetics study of the long wave-length dye/hexaarylbiimidazole systems

o-Chloro-hexaarylbiimidazole (o-Cl-HABI) can be sensitized efficiently by t he dyes 1-ethyl-3'-methyl thiacyanine bromide (C1), 3,3'-diethyl thiacarboc yanine iodide (C2), and cyclopentanone 2,5-bis[2-(1,3 -dihydro-1,3,3-trimet hyl-2H-indol-2-ylidene)ethylidene] (C3) through electron transfer proceses. When exposed to a xenon lamp (filtered by Pyrex glass), the photosensitive systems composed of o-Cl-HABI and the above dyes can produce free radicals which initiate the polymerization of MMA. The photopolymerization kinetics equation was obtained for the o-Cl-HABI/C2 system, R-p = K [C2](0.75)[o-Cl -HABI](0.44)[MTA](0.12)[MMA](1.0). A comparison of the influence of differe nt dyes on the conversion of MMA photopolymerization was conducted.