A novel polyaniline-dodecyl benzenesulfonic acid/polyurethane (PANI-DBSA/PU) blend with very high dielectric constant (epsilon(r) similar to 1120) has been developed in this work. This blend was prepared by in situ polymerization of aniline in a well-dispersed aqueous solution of PU (ISP-blend). The dielectric constant of this blend increases with the content of PANT, and rises drastically as PANT-DBSA content exceeds 15 wt.%. Similar PANI-DBSA/PU blends prepared by simple solution mixing method (SM-blend) show no resemblance in the dielectric, conductive and thermal behaviors as compared to that of the ISP-blends. Significant different morphologies are observed by SEM for these two types of blends, i.e. a homogeneous structure was found in the ISP-blends, while an inhomogeneous phase segregated with PANT particulates was shown by the SM-blends. The ultra high dielectric constant exhibited by the ISP-blend is attributed mainly to the electrode polarization effect generated by the PANT component within the blend. (C) 2003 Elsevier B.V. All rights reserved.
