Dielectric film with ultrahigh thermal stability based on crosslinked polyarylene ether nitrile is prepared and characterized. The film is obtained by solution-casting of polyarylene ether nitrile terminated phthalonitrile (PEN-Ph) combined with post self-crosslinking at high temperature. The film shows a 5% decomposition temperature over 520 °C and a glass transition temperature (Tg) around 386 °C. Stable dielectric constant and low dielectric loss are observed for this film in the frequency range of 100–200 kHz and in the temperature range of 25–300 °C. The temperature coefficient of dielectric constant is less than 0.001 °C−1 even at 400 °C. By cycling heating and cooling up to ten times or heating at 300 °C for 12 h, the film shows good reversibility and robustness of the dielectric properties. This crosslinked PEN film will be a potential candidate as high performance film capacitor electronic devices materials used at high temperature.

A novel polyarylene ether nitrile terminated with phthalonitrile (PEN-t-Ph) was synthesized by a simple solution polycondensation of biphenyl and hydroquinone with 2,6-dichlorobenzonitrile, followed by termination with 4-nitrophthalonitrile. The PENt-Ph/1,3,5-Tri-(3,4-dicyanophenoxy) benzene (TPh) system was prepared by cure treatment. The phthalonitrile on PEN-t-Ph were thermally crosslinked with TPh in the presence of diamino diphenyl sulfone through cure treatment up to 280-340 C, which led to the transformation from thermoplastic polymers to thermosetting polymers. This is because the phthalonitrile on the PEN-t-Ph can react with TPh by forming phthalocyanine ring. The glass transition temperatures of the PEN-t-Ph/TPh system increased from 152.4 C to 194.7 C, and the initial decomposition temperature (ranging from 475.3 C to 544.0 C) increased by 68 C after thermal curing. Therefore, their thermal properties can be greatly enhanced by crosslinking.

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The hydroquinone (HQ) and bisphenol A (BPA) type poly(arylene ether nitrile) (PEN) (HQ/BPA-PEN) were synthesized through nucleophilic aromatic substitution polymerization from HQ, BPA, and 2,6-dichlorobenzonitrile (DCBN). The prepared copolymers were characterized by intrinsic viscosity, Fourier transform infrared (FTIR), and dynamic rheological analysis. The properties of resultant copolymers were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and mechanical testing. The results showed that the PEN copolymers exhibited crystallization performance with excellent thermal and mechanical properties. HQ/BPA-PEN10 was made into films by solution-casting process and then were treated at different temperatures (200, 260, 280, 300, 310, and 320 8C) for different times (1, 2, 3, 4, and 5 h) to investigate the crystallinity. Results showed that when isothermal treatment temperature is 310 8C and isothermal treating time is 4 h, HQ/BPA-PEN10 showed best properties. At this condition, the melting enthalpy, crystallinity, tensile strength, and elongation at break of the sample is 17.7 J/g, 14.11%, 132.9 MPa, and 6.1%, respectively.

The core-shell structured polyaniline-functionalized-BaTiO3 (BT@PANI) nanoparticles with controllable shell layer thicknesses are developed via in-situ aniline polymerization technology and characterized in detail. The results prove that the PANI shell layer with the adjustable and controllable thicknesses of 3–10 nm are completely stabilized on the surface of the BaTiO3 core. In addition, the BT@PANI nanoparticles are regarded as the hybrid nanofillers to prepare PEN/BT@PANI nanocomposite films with a PEN matrix. The research results indicate that the surface functionalized nanoparticles facilitate the compatibility and dispersibility of them in the PEN matrix, which improves the properties of the PEN/BT@PANI nanocomposites. Specifically, the PEN/BT@PANI nanocomposites exhibit thermal stability, excellent permittivity-frequency, and dielectric properties-temperature stability. Most importantly, the energy density of nanocomposites is maintained at over 70% at 180 °C compared with that at 25 °C. All these results reveal that a new way to prepare the high-performance PEN-based nanocomposites is established to fabricate an energy storage component in a high temperature environment.