4-N,N-Dimethylamino-4'-Isopropylbenzophenone as polymerization photoinitiator. Effect of solvent and photoinitiator concentration on its photoreactivity and on the polymerization process

✍ Scribed by J. L. Mateo; P. Bosch; F. Catalina; R. Sastre

• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 480 KB
• Volume: 28
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/pola.1990.080280612

✦ Synopsis

Abstract

Several kinetics aspects of the methyl methacrylate (MMA) polymerization using 4‐dimethylamino‐4'‐isopropylbenzophenone (PI) as photoinitiator have been studied. The order of the polymerization reaction with respect to monomer and initiator concentrations have been investigated, as well as the polymerization behavior under well‐stirred and unstirred conditions; values of initiation quantum yield (ϕ__~i~__) and k~p~/k~t~^1/2^ have also been determined. It has been found that the nature of the polymerization‐initiating radicals depends on the type of solvent and the photoinitiator concentration ([PI]). In cyclohexane solution and at low [PI] (< 5 x 10^‐5^M), the cyclohexyl radical is practically the only polymerization initiating radical, while at higher [PI] both radicals, cyclohexyl and the aminoalkyl derived from PI, participate in the initiation step, increasing the participation of the later as the [PI] increases. When benzene is used as solvent both phenyl and aminoalkyl radicals participate in the initiation step at any [PI] employed. Efficiencies of the radicals derived from solvent and photoinitiator have been determined.