Photosensitized degradation of polymers

This Report follows the format of the previous one except that, commencing this year, the patents section will be omitted. Academic and industrial research in this field continues to be prolific, particularly in areas of photopolymerization such as electron beam curing and photoresists. Other areas, such as the photosensitized degradation of polymers for producing photodegradable plastics, have diminished to only a few articles, and consequently these will now be included in the section dealing with photo-oxidation and photodegradation. 

In photosensitized degradation of polymers it is most important to know whether the transferred energy is suffioient to effeot the scission of bonds in aoceptor macromolecules. 

Stannett and coworkers (17, 18) have shown that anthraquinone-sensitized photopolymerizations on celluloses and nylon involve the triplet state of the dye and semiquinone intermediates in photoinitiation. In addition, anthraquinones (17, 18) were also known to photosensitize degradation of polymers. 

Dye photosensitized degradation of polymers is a phenomenon commonly known in industry as phototendering. However, the mechanism of phototendering not only involves the singlet oxygen oxidative mechanism, but also various free radical processes, the formation of oxygen radical ions ( 2 ) and other oxygen reactive species, and it is very complex. 

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