On the assignment of the room temperature ESR spectrum of gamma irradiated poly(ethylene glycol dimethacrylate)

✍ Scribed by L. Brown; T.G. Carswell-Pomerantz; D.J.T. Hill; P.J. Pomery

• Book ID: 103991248
• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 271 KB
• Volume: 48
• Category: Article
• ISSN: 0969-806X
• DOI: 10.1016/0969-806x(96)00074-6

✦ Synopsis

The ESR spectrum of poly(ethylene glycol dimethacrylate) observed at room temperature following gamma radiolysis is characterized by an eleven-line spectrum. Some authors have assigned the outer lines in this spectrum to the presence of formyl radicals which have been stabilized at the prevailing temperature by the cross linked network. In this paper we re-evaluate this assignment and show that a more likely explanation of the spectrum is that there is that there are three conformations of the propagating radicals present, corresponding to the three possible rotational conformers which can be formed about the fl-methylene group. It is suggested that the third conformer, which is not found for poly(methyl methacrylate) and most other methacrylate polymers, is stabilized by the cross linked structure of this polymer. A similar explanation is suggested as an explanation for the eleven-line ESR spectrum observed for poly(methacrylic acid) following irradiation at room temperature, where the stabilization is suggested to occur due to hydrogen bond through the carboxyl groups.