Piezoelectric cellular polymer films: Fabrication, properties and applications

Abstract

Piezoelectricity can be defined as the ability of certain materials to provide mechanical–electrical energy conversion. In addition to traditional ferroelectric polymers (such as polyvinylidene fluoride, PVDF) and ceramics (such as lead zirconate titanate, PZT), charged polymer film foams have also shown important piezoelectric activity. In fact, when cellular polymers are exposed to high electrical fields, positive and negative charges are created on the opposite faces of each cell surface. As a result, charged cellular polymers can exhibit ferroelectric-like behavior and may therefore be called ferroelectrets. The piezoelectric effect of these materials is known to be affected by several parameters such as the cellular structure (cell density, shape and size), relative density and elastic stiffness. However, a careful morphology control is mandatory to optimize the piezoelectric response.<br />Ferroelectrets have recently received a great deal of academic and industrial interest due to their wide range of technological applications associated with high piezoelectric constants, low cost, flexibility and low weight. In this paper, an overview of different piezoelectric cellular polymers is presented with recent developments and applications.