Co-photolysis of polystyrene hydroperoxide with poly(vinylacetophenone)

✍ Scribed by Neil A. Weir; J. Arct; J.K. Lee

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 469 KB
• Volume: 29
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(93)90136-4

✦ Synopsis

Films made from poly(styrene) hydroperoxide (PSOOH) and poly(vinylacetophenone) (PVAP) were exposed to long-wave (2/> 300 nm) u.v. radiation under high vacuum at 25 + I °. The presence of PVAP considerably enhanced the rate of decomposition of PSOOH, the quantum yield increasing by a factor of 2.5. New hydroxyl groups were formed as a result of photoreduction of the PVAP and of abstraction by the initially formed alkoxy radicals. In addition to the products of photolysis of PVAP (methane, ethane and CO), other low molecular weight species were detected, viz. water, CO2, benzaldehyde, acetophenone, 02 and benzene. The yield of CH 4 was about four times that produced from PVAP alone; this effect was attributed to abstraction of the hydroxylic H-atom of PSOOH by CH~ radicals from PVAP. Molecular weight and GPC measurements indicate that chain scission occurs in the earlier stages of the reaction, but its effects are rapidly overwhelmed by cross-linking, which appears to be particularly facile. The rate of decomposition of PSOOH is linearly dependent on the hydroperoxide content of the polymer and on the PVAP concentration at lower concentrations. However, higher PVAP concentrations lead to an accelerating rate of decomposition. The higher quantum yield for PSOOH disappearance is attributed to sensitized decomposition involving both CH 3 radicals and keto groups from PVAP. The mechanism of these reactions are discussed.