|
|
|
|
J. Nagasawa, R. Bhatnagar, and F. Nakanishi
[J. Photopolym. Sci. Technol., Vol.6, No.1, pp.139-142, 1993]
Poly(vinyl alcohol)s having pendent monohexyl or monodecyl ester of p-phenylenediacrylic acid (p-PDAmC_{n}-PVA; n=6,10) were synthesized. The absorption spectra of these polymers in dichloromethane have a maximum at 320 nm and are similar to those of dialkyl esters of p-PDA. On irradiation of a polymer solution with a 313-nm light, cycloaddition of double bonds proceeds rapidly enough to compete with trans-cis isomerization. This reaction way is very different from that in the case of diester solution. On irradiation of a diester solution, the trans-cis isomerization is much faster than cycloaddition of double bonds so that the isomerization is dominant and reaches photostationary state during the first stage of the irradiation. The formation of cyclobutane ring proceeds slowly during longer term. These facts suggest that p-PDA chromophores of the polymer exist in association with each other even in the solution. The fluorescence spectra of polymers also support this explanation. The absorption spectra of polymer films have a maximum is 306 nm. The result of irradiation indicates that the p-PDA chromophores also aggregate in the polymer film.
