Photodimerization of thioxanthone-anthracene: formation of monochromophoric Type II initiator

Balta D., ARSU N.

DESIGNED MONOMERS AND POLYMERS, vol.19, no.3, pp.222-226, 2016 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 19 Issue: 3
  • Publication Date: 2016
  • Doi Number: 10.1080/15685551.2015.1136528
  • Journal Name: DESIGNED MONOMERS AND POLYMERS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.222-226
  • Keywords: Anthracene, fluorescence, photodimerization, thioxanthone, FREE-RADICAL POLYMERIZATION, SELECTION-RULES, DIANTHRACENE, DIMERIZATION, COPOLYMER
  • Yıldız Technical University Affiliated: Yes

Abstract

Thioxanthone-anthracene (TX-A) was previously synthesized and used as an initiator for the polymerization of acrylates and methacrylates in air atmosphere. Photodimerization of TX-A was carried out in benzene under light irradiation of >350nm, and dimer (diTX-A) formation was followed by UV-vis, fluorescence and phosphorescence spectroscopy. The conjugation of anthracene was destroyed after dimerization, and the thioxanthone group was left behind. Therefore, the typical thioxanthone absorption spectrum was seen at 380nm. TX-A itself does not have phosphorescence emission; however, diTX-A displayed phosphorescence emission spectrum similar to thioxanthone. IR and H-1 NMR spectrophotometric techniques also helped to determine the structure of diTX-A. Furthermore, photopolymerization of methyl methacrylate (MMA) in the presence of dimer (diTX-A) was another proof of the photodimerization of TX-A. diTX-A initiated polymerization of MMA as good as thioxanthone in the nitrogen atmosphere and displayed typical Type II initiator behaviour.