Photosensitization properties of thermoresponsive polymer containing a benzophenone fragment

ORGN 503

Hisao Koizumi, koizumi@cheng.es.osaka-u.ac.jp, Yasuhiro Shiraishi, shiraish@cheng.es.osaka-u.ac.jp, and Takayuki Hirai. Research Center for Solar Energy Chemistry, Osaka University, 1-3 Machikaneyama-cho, Toyonaka, 560-8531, Japan
We previously reported that a polymeric photosensitizer, consisting of N-isopropylacrylamide and benzophenone units, acts as the first sensitizer enabling photooxygenation rate control by temperature (J. Am. Chem. Soc., 128, 8751 (2006)). In the present work, we studied the effects of polymer amount in solution and the quantity of BP unit within the polymer on the photosensitization activity. We found that the photosensitization activity depends strongly on these factors. The most notable fact is that the optimization of these factors enables “clear-cut” change in the sensitizing activity, showing high sensitizing activity at low temperature while showing zero activity at high temperature. We report here the detailed mechanism of the sensitizing activity.