Lifen Tong

Influence of hyperbranched copper phthalocyanine grafted carbon nanotubes on the dielectric and rheological properties of polyarylene ether nitriles

Novel hyperbranched copper phthalocyanine covalently grafted carbon nanotube/polyarylene ether nitrile (HBCuPc-CNT/PAEN) flexile composite films were prepared via solution casting. The CNTs are enwrapped by a functional intermediate HBCuPc thin layer which forms a rough shell on the surface of the CNTs to ensure a good dispersion of CNTs in the PAEN matrix. The dielectric layer (HBCuPc-CNTs) is intercalated by insulating layers (pure PAEN, acting as the isolating layer). Due to the high capacitance of the dielectric layer and the effective blocking of the mobility of free charge carriers by the insulating layers, the polymer-based composite films exhibit not only a high permittivity but also an extremely low dielectric loss and excellent breakdown strength. SEM images show that HBCuPc-CNTs are perfectly embedded in the matrix and no pull-out phenomenon can be observed. In addition, the rheological properties of the resulting composite films also indicate that the grafted CNTs present a good dispersion and strong interactions with the PAEN resin, thus resulting in a significant improvement of the mechanical and thermal properties of the PAEN composite films.

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 (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.

Composites of Core/Shell-Structured Copper-Phthalocyanine-Decorated TiO2 Particles Embedded in Poly(Arylene Ether Nitrile) Matrix with Enhanced Dielectric Properties

Polymer-based composite films were prepared by employing core/shell-structured tetranitrophthalocyanine copper/titanium dioxide (TNCuPc–TiO2) hybrid particles as fillers and poly(arylene ether nitrile)s (PEN) as polymer matrix. Core/shell-structured TNCuPc–TiO2 hybrid particles were successfully synthesized through a facile solvothermal synthesis route. Compared with raw TiO2, the dispersibility and interfacial compatibility between TNCuPc–TiO2 hybrid particles and PEN matrix were observably improved because the TNCuPc decorated on the TiO2 can interact with nitrile groups in PEN. Consequently, core/shell-structured TNCuPc–TiO2 had a more significant enhancement effect on the properties of PEN. Although the mechanical strength was reduced to 41 MPa, all of the composite films exhibited excellent thermal stability. Their initial decomposition temperatures were up to 510°C, and the glass-transition temperatures were over 191°C. More importantly, the permittivity of the composite film was as high as 19.8 at 100 Hz when the weight fraction of TNCuPc–TiO2 hybrid particle loading reached 40.0 wt.%. Compared with the permittivity of PEN/TiO2 composite films with 40.0 wt.% raw TiO2 particle loading, the dielectric constant was increased by 161%.

Mechanical and dielectric properties of crystalline poly(arylene ether nitrile) copolymers

Poly(arylene ether nitrile) (PEN) copolymers (HQ/RS-PEN) containing different proportions of hydroquinone (HQ-PEN) block and resorcinol (RS-PEN) block were synthesized, and their crystalline, mechanical, and dielectric properties were investigated. Three HQ/RS-PEN copolymers with 10%, 20%, and 30% of RS-PEN blocks were prepared via condensation polymerization of HQ and RS with 2,6-dichlorobenzonitrile. The PEN copolymers were characterized and confirmed by Fourier transform infrared spectroscopy, intrinsic viscosity, and thermal analyses. With the addition of RS-PEN block, the flexibility of PEN copolymers was increased. In addition, even though the high loading content of RS-PEN block was incorporated, the PEN copolymers still exhibited relatively high dielectric constant, whereas the dielectric loss decreased. Furthermore, to investigate the effect of treatment time and temperature on the physical properties of crystalline PEN copolymers, HQ/RS-PEN20 was isothermally treated at different temperatures (280°C, 300°C, 310°C, 320°C, and 330°C) for a constant time and at a constant time for different hours (1, 2, 3, 4, and 5 h). After the optimization of the crystallization of HQ/RS-PEN polymer, excellent mechanical and dielectric properties of copolymers were obtained. The results showed that when isothermally treated at 320°C for 2 h, the HQ/RS-PEN20 showed optimal properties of tensile strength of 117.6 MPa and dielectric constant of 4.07 at 1 kHz.

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.

Preparation and physical properties of polyarylene ether nitrile and polyarylene ether sulfone random copolymers

Polyarylene ether nitrile sulfone (PENS) random copolymers consisting of polyarylene ether nitrile (PEN) and polyarylene ether sulfone (PES) were prepared from bisphenol A, bis(4-chlorophenyl)sulfone, and 2,6-dichlorobenzonitrile by the nucleophilic aromatic substitution polymerization. The structure of the PENS random copolymers was confirmed by Fourier transform infrared spectrometer and 1H nuclear magnetic resonance, and the properties of the PENS copolymers were investigated by thermal analysis (differential scanning calorimetry and thermogravimetric analysis), inherent viscosity measurements, mechanical tests, and dielectric tests. The samples showed excellent thermal stability, with the 5% weight loss temperature (T 5%) greater than 480°C under nitrogen and glass transition temperature (T g) greater than 180°C. The tensile strength, tensile modulus, and elongation at break of the PENS copolymers were improved with the increase of the PEN content, indicating the better mechanical property of PEN than that of PES. The dielectric constant and dielectric strength of the PENS random copolymers were also enhanced with the increase of the PEN content. As a result, PENS100 showed the highest energy storage density, which is 0.68 J/cm3. PES showed better thermal properties while worse mechanical and dielectric properties compared with PEN. PENS copolymers combined the excellent properties of PEN and PES due to the compatibility between them.

Novel in-situ nanocomposites of phthalonitrile end-capped polyarylene ether nitrile/copper phthalocyanine

A novel phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph)/copper phthalocyanine (CuPc) nanocomposites which possesses crosslinking reaction combined with crystallization behaviour were prepared successfully through in-situ reaction and hot-compression. In the presence of copper ion, CuPc were formed through crosslinking reaction among the phthalonitrile at the end of the PEN-Ph main chain and 1, 3, 5-Tri-(3, 4-dicyanophenoxy) benzene (TPh). Besides, the formed CuPc can play the role of nucleating agent to improve the crystallinity of the polymers. The influence of the crosslinking reaction and crystallization behaviour were investigated. The results show that the crystallization and crosslinking coexist in the system at the same time. Scanning electron microscope (SEM) images show that the crystals of the PEN-Ph grow after the hot-compressing procedure. Moreover, the glass transition temperature (Tg) increases while the crystallinity declines slightly with the low amount of copper ions. The inc...