Preparation and characterization of silica/polyimide nanocomposite films based on water‐soluble poly(amic acid) ammonium salt

Abstract

In this article, a series of new silica/polyimide (SiO2/PI) nanocomposite films with high dielectric constant (>4.0), low dielectric loss (<0.0325), high breakdown strength (288.8 kV mm−1), and high volume resistivity (2.498 × 1014 Ω m) were prepared by the hydrolysis of tetraethyl orthosilicate in water‐soluble poly(amic acid) ammonium salt (PAAS). The chemical structure of nanocomposite films compared with the traditional pure PI was confirmed by Fourier transform infrared spectroscopy and X‐ray diffraction patterns. The results indicated that both the PAAS and the polyamide acid (PAA) material were effectively converted into the corresponding PI material through the thermal imidization and the amorphous SiO2 was embedded in the nanocomposite films without structural changes. Thermal stability of the nanocomposite films was increased though mechanical property was generally decreased with increasing the mass fraction of SiO2. All the nanocomposite films exhibited an almost single‐step thermal decomposition behavior and the average decomposition temperature was about 615°C. It was concluded that the effective dispersion of SiO2 particles in PI matrix vigorously improved the comprehensive performance of the SiO2/PI nanocomposite films and expanded their applications in the electronic and environment‐friendly industries. POLYM. COMPOS., 38:774–781, 2017. © 2015 Society of Plastics Engineers

Superhydrophobic and elastic silica/polyimide aerogel based on double confinement growth strategy of the co-sol system

“…Water-soluble PI is synthesized using water-soluble polyamic acid salt (PAAs) as a precursor. 34,35 PAAs can be mixed with various water-soluble substances, including SiO 2 , graphene and cellulose to improve the properties of PI aerogels, such as hydrophobicity, electrical conductivity and flexibility. Mixing with water-soluble substances shows advantages that the traditional preparation of PI aerogels with polyamic acid (PAA) as a precursor does not have.…”

Aqueous solution blending route for preparing flexible and antistatic polyimide/carbon nanotube composite films with core‐shell structured polyimide/graphene microspheres

“…In recent years, waterborne PI has been gaining attention because of its easy storage and environmental friendliness. [42][43][44][45] Herein, in this paper, poly(amic acid) ammonium salts (PAAS) aqueous solution was applied as the dispersion system of PI@rGO composite microspheres to fabricate composite films, which not only can avoid destruction of the core-shell structure, but also can prevent cracks on the composite film by means of the bonding effect of the PI matrix. In addition, PI@rGO composite microspheres are attached to 1D CNTs to construct a 3D conductive network structure within polyimide films.…”

Geometric analysis of dielectric failures in polyimide/silicon dioxide nanocomposites

“…The growing appeal of these modern materials has encouraged examinations on the causes and limits of their enhanced properties. Although extensive work has been done to investigate the effects of silica concentration and nanoparticle dispersion on properties such as dielectric strength and CTE, there is still much to be learned about how a PI/silica nanocomposite's properties are enhanced . Moreover, the investigation into the effect of nanoparticle integration on the mechanisms of dielectric breakdown is in the early stages .…”

“…As polyimide is a good candidate for wire insulating materials, it is important to understand how its ability to withstand strong electric fields can be affected by nanoparticles. Some data have suggested that the dielectric strength of PI/silica nanocomposites weakens with the addition of silica nanoparticle content, while others suggest a more complicated relationship . Because silica exhibits a lower dielectric strength than polyimide, it stands to reason that a PI/silica composite would exhibit a diminished dielectric withstand capability compared to pure PI due to property sharing in nanocomposites.…”