Photoreactions of poly(o-butyrylstyrene) in the long-wave region

✍ Scribed by N.A. Weir; J. Arct; A. Ceccarelli

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 591 KB
• Volume: 72
• Category: Article
• ISSN: 1010-6030
• DOI: 10.1016/1010-6030(93)85090-u

✦ Synopsis

Poly(o-butyrylstyrene) (POBS) was exposed in the form of thin films to long-wave UV radiation (ha300 nm) under high vacunm at 25 ): 1 "C. Ethylene was the principal low-molecular-weight product, but much smaller amounts of CO, methane, ethane and propane were also formed. Quantum yields for gaseous product formation were low, indicating that the Nourish type I and II reactions, which lead to their production, are subject to competition from the relatively favourable photoenolization. Transient spectra indicate the presence of the synand anti-enols, which have lifetimes of 140 ns and 4.7 ps respectively. Molecular weight data indicate that crosslinking occurs, but to a much lesser extent than in the isomeric p-acylstyrene polymers, both the Norrish type II reaction and photoenolization competing with free radical production. Other spectroscopic measurements indicate a minimal depletion of the carbonyl concentration, which is consistent with the predominance of these reactions. In terms of photodegradation, POBS is a relatively photostable polymer.