Photocrosslinking of poly(2,3-epithiopropyl methacrylate) film with 254 nm irradiation

✍ Scribed by Egawa, Hiroaki ;Ishikawa, Masataka ;Tsunooka, Masahiro ;Ueda, Toshihiro ;Tanaka, Makoto

• Publisher: John Wiley and Sons
• Year: 1983
• Weight: 338 KB
• Volume: 21
• Category: Article
• ISSN: 0360-6376
• DOI: 10.1002/pol.1983.170210217

✦ Synopsis

Abstract

Poly(2,3‐epithiopropyl methacrylate) (PETMA) has an absorption maximum at 258 nm (ε~max~ = 50) in dioxane which is due to episulfide groups. When irradiated at 254 nm under atmospheric pressure its film became insoluble. When kept at 70°C for several minutes a PETMA film became partially insoluble; however, the contribution of this thermal reaction to the photocrosslinking at room temperature was negligible. For photoreaction at 254 nm under nitrogen a low probability of main‐chain scission was ascertained by the use of the Charlesby‐Pinner equation. The IR spectrum of irradiated PETMA showed a decrease in episulfide groups and the formation of mercapto groups, which suggested that the photocrosslinking of PETMA results from free radicals formed by the cleavage of CS bonds. Free radicals in the irradiated PETMA were detected by ESR spectroscopy and the assignment is discussed. In this photocrosslinking process oxygen was a retarder at the early stage but an accelerator at the later stage.