Relaxation studies of thin films oriented by corona poling for a poly(p-phenyleneterephthalate) with nonlinear optical side groups

We report relaxation studies of corona-poled aromatic polyester bearing a n onlinear optical (NLO) chromophore as a side group. The effects of film thi ckness on the temporal stability of the NLO coefficient and atomic force mi croscope observation of corona-poling-induced film surface roughening are p resented. The results indicated that this material exhibits exceptionally g ood temporal stability of the second-harmonic generation coefficient at roo m temperature even though its glass transition temperature, T-g is quite lo w. The temporal stability of the chromophore orientation seems to result fr om the coupling between the chromophore and its anisotropic surface domain environment. Thus, the design strategies to lock the domain itself would be valuable for improving geometrically long-term stability of second-order N LO properties. (C) 1999 American Institute of Physics. [S0003-6951(99)04714 -2].