Interestingly, CTC can act as dual photo/thermal photoinitiators both in cationic and free radical photopolymerizations. Also, low optical density of the CTC in resins allowed to access extremely thick samples and composites. The possibility of extending wavelength sensitivity of photopolymerizations by excited state complexes (exciplexes) is also discussed. In this work, three enone dyes (C3s) bearing N-alkylated pyrrole (C3PY), indole (C3ID) and carbazole (C3CZ) group were synthesized and characterized to explore the effect of peripheral group on their photoinitiation ability. Under 405/460 nm LED irradiation, the polymerization kinetics of a diacrylate monomer in the presence of one-component C3s or bimolecular C3s/triethanolamine (TEOA) were investigated by Real-time FT-IR technology.Ĭ3s display good light absorption in the region of 300 - 500 nm. Polymerization profiles show that C3s could initiate the polymerization and TEOA significantly promote the initiation efficiency of C3CZ, while this acceleration effect is relatively small for C3PY and C3ID. To decipher these phenomenon, steady state photolysis, cyclic voltammetry and theoretical calculation were jointly performed. Accordingly, it is proposed that C3PY and C3ID tend to photolyze through intramolecular hydrogen abstraction. This work show that the peripheral group strongly affect the initiation ability of enone photoinitiator. Photopolymerization is the subject of a growing interest both at industrial and academic levels because it provides high reaction kinetics, low emissions of volatile organic solvents and in some cases, low shrinking stress. This polymerization route has been largely developed using radical polymerization of vinyl monomers, but to a lesser extent by ring-opening polymerization (ROP).
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