Two iron-arene complex photoinitiators with different substituents in arene ligands were synthesized, their activities in initiating photopolymerization of cyclohexene oxide (CHO) were compared with that of IRGACURE 261, a commercialized photoinitiator from Ciba-Geigy. A higher activity was found when the arene ligand was substituted with a stronger electron donating group. For the system initiated by IRGACURE 261 the concentration of active centers in CHO polymerization was determined and it was found that the concentration is maximum at around 35℃. The post (dark) polymerization was significant, the polymerization yield decreased with the increase of irradiation temperature and increased with the increase of post polymerization temperature. The results are interpreted based on the mechanism proposed by Lohse, et al..
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