Polymer Piezoelements Based on Porous Polyvinylidene Fluoride Films and Contact Electrode Polyaniline Layers

The preparation method to obtain the new hybrid piezoelectric systems is developed. In it, layer-by-layer oxidative polymerization of aniline is performed in situ on porous polyvinylidene fluoride films prepared by melt extrusion. The formation of conducting form of polyaniline (i.e., emeraldine salt) is confirmed by IR spectroscopy. The samples with double polyaniline layers exhibit a higher electrical conductivity than single-layer ones, with the electrical conductivity growing as the degree of substrate's orientation increases. The observed effect is related to improved uniformity and structural ordering of the conducting layer, as shown by scanning electron microscopy. The obtained hybrid systems exhibit a higher mechanical strength, elastic modulus, and break elongation, compared to the substrate. The electric and piezoactive properties of prepared samples are studied by cyclic voltammetry and by measuring their piezoelectric modulus; the deposited polyaniline layers served as the contact electrode material in these measurements. The values for piezoelectric coefficients were measured in variuos directions of applied mechanical load.