Abstract: The infrared laser induced photopolymerization kinetics of TMPTA, with a novel cationic cyanine dye borate complex(CBC), 1,3,3,1',3',3'-hexamethyl-11-chloro-10,12-propyleneindo-tricarbocyanine triphenylbutyl borate as photoinitiator, was investigated by Real-Time FTIR(RTFTIR) in this paper. The CBCadopted here has maximum absorption wavelength λ_max at 790 nm(in TMPTAphotopolymerization sample). The photopolymerization system consisted of equal weight of a monomer (trimethylolpropanetriacrylate, TMPTA), a binder(AA/MMA/St/BAcopolymer), and different content of CBC. The double bond conversion( Y ) was determined from the drop of the absorption at 1620 and 1635 cm^-1 in FTIRspectra and was continuously monitored by RTFTIRduring laser irradiation. Yincreased rapidly in the first 10 seconds and reached 37% for laser irradiation power of 17.0 mW/cm², CBCcontent of 2.0% and sample thickness of 20 μm. Higher Yand polymerization rate( R_p) could be achieved by increasing the laser power or decreasing the sample thickness. Furthermore, there existed a critical content for CBC, below which the increasing of CBCconcentration would improve Yand R_p. Higher CBCcontent over the critical value would lead to the "filter effect", which prevents the laser beam from penetrating into the deep layer of the sample, and then deteriorates the photopolymerization. The quantum photopolymerization yield of this system was 41.8 mol/einstein.

Key words: Real-time FTIR, Infrared laser, Cationic cyanine dye borate complex