Three amorphous piezoelectric polyimides have been synthesized and characterized to analyze their utility for high‐temperature applications. The studied polyimides have been prepared from 4,4′‐oxydiphthalic anhydride and the diamines 2,4‐di(3‐aminophenoxy)benzonitrile (poly2‐4), 2,6‐bis(3‐aminophenoxy)benzonitrile (poly2‐6), and 1,3‐bis‐2‐cyano‐3‐(3‐aminophenoxy)phenoxybenzene (poly2CN). These polyimides differ in the position of the dipolar groups CN in the aromatic ring (poly2‐4 and poly2‐6) and in the number of these groups in the repetitive unit (poly2‐6 and poly2CN). The imidization degree has been studied by Fourier transform infrared (FTIR) and thermogravimetry‐mass spectrometry (TG‐MS) and thermal properties by differential scanning calorimetry (DSC) and thermogravimetry (TG). The piezoelectric behavior has been analyzed from remnant polarization measurements. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 722–730, 2009

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Polyaniline (PANI) is one of the most widely used conductive polymers because of its ease of synthesis in addition to its good electrical properties. However, the difficulty in its processability limits its potential applications. In this work, conductive emeraldine salt (i.e., one of the different oxidation states of PANI) was synthesized by oxidative chemical polymerization. Different techniques such as Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and dynamical mechanical thermal analysis were used to characterize the synthesized PANI. The processability of PANI has been improved

The piezoelectric polymeric sensors and actuators are widely valued because of their low density, availability to obtain complex shapes, and easy processing among other characteristics. However, there are not many useful piezoelectric polymers. Aromatic polyimides are high‐performance polymeric materials characterized by thermal stability, chemical resistance, and excellent mechanical properties. Besides, some of these polymers have been reported as candidates to present piezoelectric properties. Our research focuses in the electric characterization of three piezoelectric amorphous aromatic polyimides, containing CN groups in different number and positions. The piezoelectricity in amorphous polymers is mainly due to the orientation polarization of the molecular dipoles, which is induced by the application of an external electrical field to a temperature over their glass transition temperature (Tg). Polyimides are measured by thermally stimulated depolarization currents and dielectric spectroscopy and the analysis of the dielectric data has been performed using the electric modulus formalism to separate conductive and dipolar processes. These measurements have evidenced that the frozen‐in polarization is mainly due to the dipole orientation of the dipolar CN groups, allowing us to understand in depth the mechanism of polarization that contributes to the piezoelectric properties. This will facilitate the obtention of materials with the best possible piezoelectric properties, comparable to those currently available but with higher mechanical and thermal performance. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012