Unusually fast optically induced birefringence in polyoxetanes bearing 4-(N,N-diphenyl)amino-4 '-nitroazobenzene chromophores

Two new polyoxetane polymers bearing azobenzene-type chromophore pendants w ere prepared, and their photoinduced molecular orientation and relaxation w ere studied. The two polymers differ in the mode of attachment of the chrom ophores, which are either laterally (Pox 1) or perpendicularly (Pox 2) boun d to the polymer backbone. The two polymers reveal unusually fast (similar to2 s to saturation at 0.4 W/cm(2)) photoinduced reorientation of chromopho res and decay behavior at room temperature. Side-on attachment of the chrom ophores (Pox 1) results in a significantly faster response to polarized lig ht and higher maximum birefringence than end-on attachment. The kinetics of photoinduced orientation and relaxation decay were quantitatively analyzed and the results are discussed in relation to the structures of the polymer s.