Isomerization Behavior of Azobenzene Chromophores Attached to the Side Chain of Organic Polymer in Organic−Inorganic Polymer Hybrids

Isomerization behavior of azobenzene chromophores in organic−inorganic polymer hybrids was investigated. Polymer hybrids were prepared from azobenzene-modified poly(2-methyl-2-oxazoline) (POZO-A) and methyltrimethoxysilane (MeTMOS) or tetramethoxysilane (TMOS). Isomerization behavior in polymer hybrids was compared with that in DMSO solution or in films of POZO-A. Two kinds of model compounds were synthesized, and their isomerization behaviors were also examined. Photoinduced trans-to-cis isomerization took place in all samples. The cis isomer ratios in the photostationary state were found to be smaller in solid films than in solution. Especially, model compound having a triethoxysilyl group showed a markedly small cis isomer ratio. Thermal cis-to-trans isomerization was investigated kinetically. A distinct deviation from the first-order kinetics was observed in solid films.