Piezoelectrets: Polymer foams for transducer applications

Piezoelectric materials are commonly used in various sensors and actuators. Besides the traditional piezoelectric ceramics such as Lead Zirconate Titanate and polar piezoelectric polymers such as β-phase Polyvinylidene Fluoride, piezoelectrets have recently become a new group of piezoelectric materials. Piezoelectrets are functional polymer systems for electromechanical transduction, with elastically heterogeneous cellular structures and internal quasi-permanent dipole moments. The piezoelectricity of piezoelectrets stems from linear changes of the dipole moments in response to external mechanical or electrical stress. Compared with the traditional piezoelectric materials, piezoelectrets own several desirable advantages. In this paper, the preparation processes and the properties of piezoelectrets were introduced and then the possible performance improvement was discussed. Finally, some promising applications of piezoelectrets were proposed.