Long-wave photodegradation of poly(3,5-dimethoxyacrylophenone) in the solid state

✍ Scribed by Neil A. Weir; Jerzy Arct; Alfredo Ceccarelli

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 487 KB
• Volume: 32
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(96)00017-1

✦ Synopsis

The photolysis of poly(3',5'-dimethoxyacrylophenone) was studied in the solid state, thin films being exposed to long-wave (i.e. 2 2 300nm) U.V. radiation under high vacuum at 25°C. The polymer underwent colouration (initially yellow) and new carbonyl species were formed. The degraded polymer reacted with o-phenylenediamine to produce a phenazine derivative which exhibited strong fluorescence at 350 nm. The intensities of NMR signals due to the methoxy carbons decreased, and, at the same time, methane and ethane were formed (quantum yields in the 10e4 region). It was concluded that O-CH, bond scission was occurring, the methyl radicals producing ethane and methane and the phenoxy radicals being transformed into quinonoid compounds to which the colouration was attributed. The polydispersity of the polymer increases during photodegradation, and this was ascribed to simultaneous chain scission and crosslinking, the former being associated with a type II decomposition and the latter being brought about by combination reactions of macro-phenoxy radicals. A plausible reaction scheme is presented.