Electron spin resonance studies of photoirradiated poly(methyl methacrylate): effect of wavelength on the formation of radical species

✍ Scribed by Ayako Torikai; Kenji Fueki

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 399 KB
• Volume: 49
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(89)87125-4

✦ Synopsis

Effective wavelengths for the photodegradation of poly(methy1 methacrylate) (PMMA) have been investigated by electron spin resonance (ESR) spectroscopy and viscosity measurements. The precursors of the photodegradation of PMMA were also studied. On photoirradiating PMMA with light of wavelengths shorter than 310 nm at 77 K in uacuo, the radical species 'COOCH, and 'CH, were observed, indicating the side-chain scission of PMMA. These radicals were not found when the irradiations were carried out with light of wavelengths longer than 310 nm. The main-chain scission of PMMA was greatly suppressed in this case. The following two conclusions were obtained from these experimental results: (1) the main-chain scission of PMMA takes place with irradiation with light of wavelengths shorter than 310 nm; (2) the radicals produced from the side-chain scission of PMMA are found to be the main precursors of the main-chain scission of PMMA. These results are also supported by the viscosity-average molecular weight measurements.