Durable crosslinked films based on poly (arylene ether nitrile) materials for ultrahigh temperature applications over 300°C

Searching for outstanding films with high temperature resistance has sparked fierce interests in the electronics industry. In this study, a novel high-temperature-resistance phthalonitrile end-capped polyarylene ether nitrile (HTR-PEN-Ph) film was fabricated via cross-linking reaction, applying two different curing programs as contrast. The fabricated HTR-PEN-Ph films were verified through FTIR, gel content test to be confirmed the cross-linking reaction. Then thermal results elucidated that PEN-Ph films treated with two-stage curing program possessed a superior glass transition temperature ( T g) in comparison with untreated one, increasing by 165–270°C. Besides, an evident increment of 5 wt.% decomposition temperature ( T 5%) was seen from the HTR-PEN-Ph film, which was 27–43°C higher than the untreated one. Furthermore, the HTR-PEN-Ph films exhibited notable dielectric stability over 300°C and mechanical properties after the two-stage curing program. Based on these satisfactory results, this study is of great potential to be applied in the field of industrial manufacture to fabricate a range of high-performance films.

Self-Toughening and Self-Enhancement Poly(arylene ether nitrile) with Low Dielectric Constant by Solid Crosslinking Reaction

A novel poly(arylene ether nitrile) terminated with hydroxyl groups (PEN-OH) was synthesized successfully. The effects of heat-treatment temperature on the thermal properties, mechanical properties, and dielectric properties of the PEN-OH films were studied in detail. Due to the cross-linking reaction occurring, at high temperature, among the nitrile groups on the side of the PEN-OH main chain to form a structurally stable triazine ring, the structure of materials changes from a linear structure to a bulk structure. Thus, the thermal properties and mechanical properties were improved. In addition, the occurrence of cross-linking reactions can reduce the polar groups in the material, leading to the decrease of dielectric constant. As the heat-treatment temperature increased, the glass-transition temperature increased from 180.6 °C to 203.6 °C, and the dielectric constant decreased from 3.4 to 2.8 at 1 MHz. Proper temperature heat-treatment could improve the tensile strength, as well as the elongation, at the break of the PEN-OH films. Moreover, because of the excellent adhesive property of PEN-OH to copper foil, a double-layer flexible copper clad laminate (FCCL) without any adhesives based on PEN-OH was prepared by a simple hot-press method, which possessed high peel strength with 1.01 N/mm. Therefore, the PEN-OH has potential applications in the electronic field.

Post Self-Crosslinking of Phthalonitrile-Terminated Polyarylene Ether Nitrile Crystals

A novel phthalonitrile-terminated polyaryl ether nitrile (PEN-Ph) was synthesized and characterized. The crystallization behavior coexisting with the crosslinking behavior in the PEN-Ph system was confirmed by rheological measurements. DSC was applied to study the crystallization kinetics and crosslinking reaction kinetics. Through the Avrami equation modified by Jeziorny, the nonisothermal crystallization kinetics were analyzed, and the Avrami exponent of about 2.2 was obtained. The analysis results of more intuitive polaring optical microscopy (POM) and SEM indicated that the shape of the crystals is similar to spherical. Moreover, the activation energy of the crystallization behavior and crosslinking behavior were obtained by the Kissinger method, and the values were about 152.7 kJ·mol-1 and 174.8 kJ·mol-1, respectively. This suggests that the activation energy of the crystallization behavior is lower than that of the crosslinking behavior, indicating that the crystallization behavior is more likely to occur than the crosslinking behavior and the crystals of PEN-Ph can be self-crosslinked to form single-polymer composites.

Flexible Ultrahigh-Temperature Polymer-Based Dielectrics with High Permittivity for Film Capacitor Applications

In this report, flexible cross-linked polyarylene ether nitrile/functionalized barium titanate(CPEN/F-BaTiO₃) dielectrics films with high permittivitywere prepared and characterized. The effects of both the F-BaTiO₃ and matrix curing on the mechanical, thermal and dielectric properties of the CPEN/F-BaTiO₃ dielectric films were investigated in detail. Compared to pristine BaTiO₃, the surface modified BaTiO₃ particles effectively improved their dispersibility and interfacial adhesion in the polymer matrix. Moreover, the introduction of F-BaTiO₃ particles enhanced dielectric properties of the composites, with a relatively high permittivity of 15.2 and a quite low loss tangent of 0.022 (1 kHz) when particle contents of 40 wt % were utilized. In addition, the cyano (⁻CN) groups of functional layer also can serve as potential sites for cross-linking with polyarylene ether nitrile terminated phthalonitrile (PEN-Ph) matrix and make it transform from thermoplastic to thermosetting. Comparing with the pure PEN-ph film, the latter results indicated that the formation of cross-linked network in the polymer-based system resulted in increased tensile strength by ~67%, improved glass transition temperature (Tg) by ~190 °C. More importantly, the CPEN/F-BaTiO₃ composite films filled with 30 wt % F-BaTiO₃ particles showed greater energy density by nearly 190% when compared to pure CPEN film. These findings enable broader applications of PEN-based composites in high-performance electronics and energy storage devices materials used at high temperature.

Crosslinked polyarylene ether nitrile film as flexible dielectric materials with ultrahigh thermal stability

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 (T_g) 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.

The effect of nitrile-functionalized nano-aluminum oxide on the thermomechanical properties and toughness of phthalonitrile resin

Resorcinol-based phthalonitrile (R-CN)/nano-aluminum oxide (Al2O3) nanocomposites were prepared via a two-step approach. Firstly, Al2O3 was functionalized with nitrile groups on the surface of Al2O3 nanoparticles, which was confirmed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy (SEM). The effect of nano-Al2O3 particles on thermomechanical and flexural properties has been evaluated for different weight ratios ranging between 0% and 5%. Compared with pure nano-Al2O3, nitrile-functionalized Al2O3 (CN-Al2O3) particles showed a more significant enhancement effect on the properties of R-CN resin. The storage modulus of nanocomposite with 5 wt% CN-Al2O3 reaches 2679 MPa at 25°C, which is much higher than that of the pure R-CN resin. For 3 wt% CN-Al2O3-reinforced R-CN composites, it showed an increase of 54.84% in flexural strength and 21.48% in flexural modulus. SEM was employed to explore the fracture surface of composites. Micrographs of fracture surface analysis confirmed that the toughness of R-CN resin can be improved significantly by incorporating CN-Al2O3 nanoparticles.

Synthesis and crosslinking study of isomeric poly(thioether ether imide)s containing pendant nitrile and terminal phthalonitrile groups

Upon crosslinking, phthalonitrile-terminated polyimide PN-PI (a–d) films exhibited better solvent resistance, and greater thermal and mechanical properties than PI (a–d) films.