High dielectric constant composites based on metal lophthalocyanine oligomer and poly(vinylidene fluoride-trifluoroethylene) copolymer

Using a solution casting method, a high dielectric constant composite based on a copper-phthalocyanine (CuPc) oligomer and a poly(vinylidene fluoride-trifluoroethylene) copolymer is developed. The experimental data show that the low field dielectric constant of the composites (with 55 wt % CuPc) can reach 1000 and the loss is similar to0.5 at room temperature and 100 Hz. Because of the long-range electron delocalization in CuPc, which results in a strong space charge response of the composite to the external field, there is a strong frequency dispersion of the dielectric properties. In addition, the dielectric properties exhibit a nonlinear behavior with electric field. At a field of 10 kV/cm, the dielectric constant at 10 Hz reaches 4500; meanwhile the dielectric loss is also high. One of the unique attributes of the composite is its mechanical properties that remain very much the same as those of the polymer matrix. Even for a composite with 55 wt % CuPc (the volume fraction of CuPc in the composite is also in the similar range), the composite film is still flexible, with a Young's modulus of 1.2 GPa at room temperature. (C) 2001 John Wiley & Sons, Inc.