Novel guest-host NLO poly(ether imide) based on a two-dimensional carbazole chromophore with sulfonyl accepters

Taking advantage of the multifunctional characteristics of carbazole along with rational molecular design, a two-dimensional (2-D) carbazole chromophore was synthesized by a facile synthetic route. By doping of the chromophores into an organosoluble poly(ether imide), a series of guest-host NLO polymers were acquired. A high doping level up to 38 wt % was obtained without observing aggregation of NLO chromophores. The second harmonic coefficients (d(33)) for the guest-host system range from 5 to 22 pm/V, dependent on the doping level. The compatibility between chromophore and poly(ether imide) was investigated by SEM and extraction experiment. In the aspect of compatibility, the molecular weight distribution of the polymer plays an important role. The effect of two-dimensional structure on the NLO temporal stability was investigated by tracing the second harmonic coefficient as functions of temperature and time, respectively. Moreover, the relaxation behavior of the NLO systems was further examined by dielectric analysis. Large rotational cone volumes give the two-dimensional chromophore excellent orientational stability when the temperature approaches the glass transition temperature observed from DEA.