Photodegradation in polymers

PL can be used as a sensitive probe of oxidative photodegradation in polymers. After exposure to UV irradiation, materials such as polystyrene, polyethylene, polypropylene, and PTFE exhibit PL emission characteristic of oxidation products in these hosts. The effectiveness of stabilizer additives can be monitored by their effect on PL efficiency. 

Trozzolo, A. M., "Stabilization Against Oxidative Photodegradation", in "Polymer Stabilization", Hawkins, W. L., Ed., Wiley-Interscience, New York, 1972. 

Electron Spin Resonance (ESR) of Photodegradation in Polymer Networks... 

Schnabel, W. (1981) Photodegradation, in Polymer Degradation, Prindples and Practical Applications. Hanser, Miinchen, Ch. 4. 

Multiphoton processes are also undoubtedly involved in the photodegradation of polymers in intense laser fields, eg, using excimer lasers (13). Moreover, multiphoton excitation during pumping can become a significant loss factor in operation of dye lasers (26,27). The photochemically reactive species may or may not be capable of absorption of the individual photons which cooperate to produce multiphoton excitation, but must be capable of utilising a quantum of energy equal to that of the combined photons. Multiphoton excitation thus may be viewed as an exception to the Bunsen-Roscoe law. 

Polymers which undergo accelerated photodegradation in the environment can be made by making a copolymer of the monomer with an unsaturated ketone. The principle of the method is shown in Scheme 9.6, using styrene as the monomer. 

Figure 18.11 Effect of exposure in New River, AZ, on the GPC data for Spectar copolymer sheeting [10]. From Photodegradation in a copoly(ethylene/1,4-cy-clohexylenedimethylene terephthalate) with and without UV absorber, presentation given by D. R. Fagerburg at the 37th International Symposium on Macromolecules, IUPAC World Polymer Congress, Gold Coast, Australia, July 1998, and reproduced with permission of IUPAC...

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