Studies of poly(ortho-acylstyrene)s. II. Photoreactions of poly(o-acetylstyrene)

✍ Scribed by N. A. Weir; K. Whiting; J. Arct

• Book ID: 105337548
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 453 KB
• Volume: 28
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/pola.1990.080280724

✦ Synopsis

Abstract

Poly(o‐acetylstyrene) (POAS) films were exposed under vacuum conditions to long wave ultraviolet radiation (λ ≥ 300 nm). Gaseous products, determined quantitatively by mass spectrometry, were methane, ethane and CO (trace), their formation indicating that POAS was undergoing Norrish Type I photodecompositions. Quantum yields for CH~4~ and C~2~H~6~ formation were more than an order of magnitude lower than the corresponding values for the isomeric poly(vinylacetophenone) (PVAP). Transient spectral measurements at 390 nm indicate the presence of enols (syn and anti), which result from the photoenolization of the ketone. Lifetimes are 161 and 4500 ns, respectively. The polymer undergoes crosslinking, the rate being much lower than that of PVAP. The mechanisms of the reactions are discussed, and it is proposed that the photostability of POAS (relative to PVAP) is the result of photoenolization, which competes favourably with degradation. POAS has considerable potential in sunlight storage applications.