Photochromic Polymer Containing Spiropyran Unit

Abstract

New photochromic monomer 1, 3, 3-trimethylindolino-6'-nitro-8'-methacryloyloxymethylspirobenzopyran was synthesized. Photochromic polymers containing spiropyran unit were obtained by homopolymerization of this monomer or copolymerization of it with styrene or methyl methacrylate as shown in Table 1. Photochromism of polymeric spiropyran in solution was studied. Absorption spectra of P(St-MSP)--1 in benzene at room temperature are shown in Fig.1. Absorption maxma (_??_) of colored kinds in visible region were influenced by the kinds of comonomer unit. These results are summarized in Table 2. This may be due to the solvent effect of polymer chain. The influences of comonomer unit and solvent on Aymasx was related to the role of them in the solvent effect on spiropyran unit. Fading of colored kinds of low molecular weight spiropyran in solution proceeded with the first order reaction. But those of polymeric spiropyran proceeded with the combined first order reactions as shown in Fig.4-1 and Fig.4-2. This specific behavior of polymeric spiropyran was interpreted in terms of the solvent effect and the steric hindrance of polymer chain. Photochromism of polymeric spiropyran in film was very different from that in solution. _??_ in film are shown in Table 2. But these results are different from the values expected from those in solution. Colored kinds of polymeric spiropyran in film faded quickly at initial stage but slowly at final stage. But they had slower fading rates in film than in solution.