A polyurethane-based elastomeric nanocomposite with a high dielectric constant

To increase the electric energy density of dielectric elastomer substantially, high dielectric constant nanocomposites were developed using polyurethane (PU) as matrix and copper phthalocyanine oligomer (CuPc)—a high dielectric constant organic semiconductor—as filler. Transmission electron microscope (TEM)-observed morphologies revealed that the sizes of CuPc particles in nanocomposite of PU chemically attached with 8.78 vol% of CuPc were in the range of 10–20 nm, much smaller than the sizes (250–600 nm) in the physical blend of PU with the same volume fraction of CuPc. At 100 Hz, the nanocomposite film exhibited a dielectric constant of 391, representing more than 60-fold increase with respect to the pure PU. The enhanced dielectric response of the nanocomposite makes it possible to induce a high electromechanical response under a much reduced electric field (a strain of 17.7 % was achieved under a field of 10 V/μm).