Dielectric Properties of Piezoelectric Polyimides

Abstract

Polyimides are the most promising amorphous piezoelectric polymers not only because of their excellent thermal, mechanical and dielectric properties, but also and, mainly due to their high glass transition temperatures. Here we report on the synthesis of polyimides with one CN (poly2-6) and two CN groups (poly2CN) in the repetition unit, the latter being synthesised for the first time. The dielectric measurements show that remnant polarisation and piezoelectric coefficients values depend strongly on the number of pendant nitrile dipoles in the repetition unit, on the orientation of the backbone anhydride dipole as well as on the imidisation and the poling processes.

Keywords:

• Piezoelectric polyimides
• dielectric measurements
• remnant polarisation
• piezoelectric coefficients

Acknowledgments

This work has been supported by programme ETORTEK (Technology Centres Foundation Iñaki Goenaga), project ACTIMAT and the Spanish Government, project MEC. MAT 2006-13571-C02-02.