Electrical properties of conventional polyimide films: Effects of chemical structure and water uptake

Abstract

A series of conventional polyimide (CPI) films, based on pyromellitic dianhydride (PMDA) and benzophenonetetracarboxylicdianhydride (BTDA), were prepared by a two step process, and their dielectrical constant, dielectrical loss, and DC conduction behaviors were studied at different frequencies and voltages. Their dielectrical breakdown voltage, water uptake, and solubility properties were also investigated. The effects of chemical structure and water uptake on the electrical properties of the films are discussed in detail. The dielectric constants of the CPI films vary between 2.93 and 3.72 at 1 MHz frequency and they are in the following decreasing order: BTDA-DDS Ͼ BTDA-DDE Ͼ PMDA-DDS Ͼ PMDA-DDE. The structure and thermal and oxidative stability of films were analyzed by FTIR-ATR and TGA, respectively. The results showed that all CPI films have good insulating properties, such as high dielectric breakdown voltage, low dielectric constant with stability for long period of frequency, and low leakage density. Our results concerning electrical properties also suggest that electron hopping is responsible for AC conduction and Poole-Frenkel mechanism is predominant for DC conduction of all CPI films.

Synthesis, characterization, and comparative study of conducting polyaniline/lead titanate and polyaniline–dodecylbenzenesulfonic acid/lead titanate composites

“…It means that a surfactant such as DBSA has an important role in modifying the properties of PANI composites by its incorporation into the composite matrix containing PbTiO 3 particles, as it does in the case of PANI with other organic dopants. [44][45][46] The incorporation of inorganic oxide particles into organic polymers offers the possibility of the formation of a plethora of novel materials with high potential for new applications. For optimal control of the properties of these new materials, it is very important to tailor the formation process from the point of view of the final product.…”

“…44,45 The increase in the dielectric properties of PANI-DBSA/PbTiO 3 may be attributed to the effect of interfacial polarization, which is known as the Maxwell-Wagner-Sillars effect. [46][47][48] This is a phenomenon observed in heterogeneous media due to the accumulation of virtual charge at the interfaces of the media. 49 After all, the dielectric properties can be drastically different, depending on the frequency at which the blends are used.…”

Synthesis and characterization of novel polyimides derived from 2‐amino‐5‐(4‐aminophenyl)‐thiazole

“…In other words, fewer polarizable groups in unit volume may lead to a lower dielectric constant for polyimide films. 22 Polyimides based on AAPT have lower dielectric constants (3.12-3.38 at 10 MHz) compared with conventional polyimides such as PMDA/ODA polyimide film (3.44 at 10 MHz). The dielectric constant values are in increasing order for our samples: PI-1<PI-2<PI-3.…”

“…Although the thickness of the polyimide films are different, the dielectric constants of the polyimide films thicker than 1 lm do not vary with the thickness. 21,22 Obviously, the dielectric constants for each sample are quite different, and strongly depend on the chemical structure. This value may be affected by decreasing the molecular packing efficiency of their chemical structures.…”

Electrospinning of polyimide nanofibres – effects of working parameters on morphology

“…[1,2] Furthermore a negligible cytotoxicity for some representatives of commercially available polyimides indicates a good biocompatibility. [3] Therefore its potential application in biomedical engineering is of high interest.…”