Photochemical behavior of poly(organophosphazenes)—XIII. Sensitized photochemistry of poly[bis(4-benzylphenoxy)phosphazene] in solution and in film

✍ Scribed by Mario Gleria; Francesco Minto; Luca Fambri; Alessandro Pegoretti

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 735 KB
• Volume: 31
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(95)00001-1

✦ Synopsis

In this paper we report the solution and solid-state photochemistry of poly[bis(4benzylphenoxy)phosphazene] sensitized by benzophenone. U.V. and Cr. spectroscopic characterizations and weight average molecular weight data indicate that the main reaction under irradiation for this polymer dissolved in benzene is the increase in molecular weight due to an efficient crosslinking process. Moreover, gel is formed very rapidly after a few minutes of light exposure, when the polymer is photolyzed in film. These results arc attributed to an intermolecular hydrogen atom abstraction reaction that takes place between the electronically excited triplets of the benzophenone photosensitizer and the methylene group present in the side 4benzylphenoxy substituent of the phosphazene polymer that generates radicals able to couple forming inter-chain links. The different behavior of the poly[bis(4-benzylphenoxy)phosphazene] when the photolysis is carried out in air or in inert argon atmosphere is also described and the presence of a post-photochemical effect in the irradiated phosphazene films is discussed.