Visible Photopolymerization Initiated by Coumarin-biimidazole System.

Abstract

Bis(7-diethylaminocoumarin) ketone-3 (DEACK) can sensitize the homolysis of o-Chlorohexaarylbisimidazole (o-C1-HABI). The radicals so generated can initiate the polymerization of methyl methacrylate (MMA) which was studied by dilatometry. The photopolymerization rate was determined to be proportional to the concentration with the exponent of 0,22,0.80,0.70 for DF.ACK, o-C1 HABI, MMA, respectively. The system can be used as initiator of laser polymerization,

Visble Light Photopolymerization of Methylmethacrylate Initiated By Titanocene.

“…Titanocene chemical structure is shown as follows: Fig.2 expresses the relationship between the rate of photopolymerization and the concentration of Titanocene. Until the concentration is higher than 4x 10"'moi/L, LgRp is still proportional to Lg [Titanocene].The result is a little different from those of the former systems which have been studied by our research group [4][5]. The major reason, we think, is the initiator photobleaching during irradiation (see Fig.5),the other is the low molar extinct coefficient of Titanocene in the visible region.…”

“…We have reported two hexaarylbiimidazole systems and obtained good results [4][5]. In this paper, we reported a new photosensitive initiating system composed of Titanocene and MMA.…”