Fabrication of crosslinked single-component polyarylene ether nitrile composite with enhanced dielectric properties

Hydrogen Bonding of Aramid Boosts High-Temperature Capacitive Properties of Polyetherimide Blends

Polyetherimide (PEI) is the state-of-the-art commercial high-temperature polymer dielectric with excellent thermal and chemical stability and relatively high high-temperature capacitive energy storage properties. The rotation of the dipoles in the PEI chains brings the β-relaxation which seriously increases the leakage current and decreases the charge-discharge efficiency. In this work, hydrogen bonds have been introduced to limit the dipole rotation of PEI by blending aramids [1,4-poly(ether fluoromethyl naphthalene amide), PNFA] into the PEI matrix. By introducing 10 wt % PNFA, the β-relaxation of the blend has been significantly reduced which could be observed from the dielectric spectrum. To explore the mechanism of limited β-relaxation, we analyze the hydrogen bonds in the blend films by infrared spectroscopy and found that the maximum content of hydrogen-bonded carbonyl formed between PNFA and PEI chains was 14.3% when the content of PNFA was 30 wt %. The content of hydrogen bonds formed between PNFA and PEI was positively correlated with the energy storage performance of the blends. The maximum discharged energy density with an efficiency above 90% of the blend film with 30 wt % PNFA reaches 4.1 J cm^-3 at 150 °C, which is about 350% higher than that of pristine PEI. This work shows that composing hydrogen bonds by the blending method could be a viable strategy for enhancing the high-temperature energy storage performance of polymer dielectrics, which could be achieved by large-scale preparation and has feasible industrial production prospects.

Synthesis and properties of polyarylene ether nitrile random copolymer containing naphthalene and biphenyl structure

A novel series of polyarylene ether nitrile (PEN) random copolymers with a higher Tg and better mechanical and electrical properties were synthesized through nucleophilic substitution polycondensation. In the means of adjusting mole ratio of 4,4′-dihydroxybiphenyl (BP) to 2,7-naphthalenediol (ND), the performance of PEN random copolymer could be controlled. The FTIR, SEM, DSC, TGA, AR, intrinsic viscosity, and electrical and mechanical properties were performed on the samples. All the samples exhibited excellent thermal performance with Tg over 210°C, Td5% over 520°C, and heat conduction higher than 0.4 W/m·k. The PEN copolymers when the molar ratio of ND was 15% had the best comprehensive performances, whose Tg was 215°C, Td5% was up to 554.31°C, thermal conductivity was 0.4430 W/m·k, tensile strength was 113.27 MPa, and stable dielectric constant (at frequency from 103 Hz to 106 Hz) was lower than 4. As a result, this PEN copolymer obtained in this paper could provide practical value and possibility in further application in the filed including machine manufacture industry, electronic materials, and automotive industry.

Dielectric polymers for high-temperature capacitive energy storage

Polymers are the preferred materials for dielectrics in high-energy-density capacitors. The electrification of transport and growing demand for advanced electronics require polymer dielectrics capable of operating efficiently at high temperatures. In this review, we critically analyze the most recent development in the dielectric polymers for high-temperature capacitive energy storage applications. While general design considerations are discussed, emphasis is placed on the elucidation of the structural dependence of the high-field dielectric and electrical properties and the capacitive performance, including discharged energy density, charge-discharge efficiency and cyclability, of dielectric polymers at high temperatures. Advantages and limitations of current approaches to high-temperature dielectric polymers are summarized. Challenges along with future research opportunities are highlighted at the end of this article.

Intrinsic high-k–low-loss dielectric polyimides containing ortho-position aromatic nitrile moieties: reconsideration on Clausius–Mossotti equation

Intrinsic high-k–low-loss dielectric polyimides containing ortho-position aromatic nitrile moieties were synthesized. 2CN-BTDA shows a D_k of 4.80, D_f of 1.57 × 10⁻³ at 1 kHz (25 °C), E_B of 219.4 kV mm⁻¹ with energy density of 1.023 J cm⁻³ and T_g of 325 °C.

Preparation of Amorphous Poly(aryl ether nitrile ketone) and Its Composites with Nano Hydroxyapatite for 3D Artificial Bone Printing

PEEK had been used to fabricate artificial bones by 3D printing widely, but it expressed unsatisfactory interlayer performance of 3D printing and weak compatibility with nano hydroxyapatite(nHA) due to the limits of molecular structures. Here an amorphous poly(aryl ether ketone) for 3D bone printing, PEK-CN, was designed and synthesized via nucleophilic substitution from 4,4'-difluorobenzophenone, phenolphthalein and 2,6-dichlorobenzonitrile, which possessed much stronger interlayer strength due to van der Waals force between polar groups(-CNs). Specifically, the stronger interlayer strength resulted in lower porosity(3% with 100% infill rate) and more comparable mechanical properties(the maximum tensile strength was ∼110 MPa) to cortical bone. Importantly, PEK-CN had passed in vitro cytotoxicity testing and samples of human mandible and maxillary bones based on PEK-CN were printed by fused deposition modeling(FDM) successfully. Moreover, PEK-CN/nHA composites were obtained to enhance bioactivity of resin, and PEK-CN without limits of crystal lattices expressed excellent compatibility with nano hydroxyapatite. Our work provided a high performance resin for 3D bone printing, which would bring better solutions for artificial bone materials.

Effect of Plasticizer and Shearing Field on the Properties of Poly(arylene ether nitrile) Composites

A novel composite film of hydroquinone/resorcinol-based poly(arylene ether nitrile) (HQ/RS-PEN) improved by bisphenol A based poly(arylene ether nitrile) (BPA-PEN) was prepared, in which BPA-PEN acts as a plasticizer, leading to improved fluidity of the material, thereby favoring the crystallinity of HQ/RS-PEN. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and mechanical and rheological tests have shown that the composites exhibited outstanding thermal and mechanical properties as well as improved fluidity and processing applicability compared with HQ/RS-PEN. At the same time, the crystallization of the poly(arylene ether nitrile) blends with 5 wt % BPA-PEN could be promoted under both static and shear flow fields. Polarizing microscope (POM) and scanning electron microscopy (SEM) showed that the crystalline morphology of HQ/RS-PEN was converted from spherulites to fibrous crystals under shearing. DSC, X-ray diffraction (XRD), and dynamic storage modulus results proved that the crystallization rate and crystallinity of HQ/RS-PEN increased significantly under the shear field. The crystallinity enhanced to a maximum of 20.1% and the melting enthalpy increased to 33.4 J/g at 310 °C under the frequency of 0.01-100 Hz for 20 min.

Fabrication and Enhanced Thermal Conductivity of Boron Nitride and Polyarylene Ether Nitrile Hybrids

Excellent thermal resistance and thermal conductivity are preconditions of materials to be used at elevated temperatures. Herein, boron nitride and polyarylene ether nitrile hybrids (PEN-g-BN) with excellent thermal resistance and thermal conductivity are fabricated. Phthalonitrile-modified BN (BN-CN) is prepared by reacting hydroxylated BN with isophorone diisocyanate (IPDI) and 3-aminophxylphthalonitrile (3-APN), and then characterized by FT-IR, UV-Vis, and X-ray photoelectron spectroscopy (XPS). The obtained BN-CN is introduced to a phthalonitrile end-capped PEN (PEN-Ph) matrix to prepare BN-CN/PEN composites. After curing at 340 °C for 4 h, PEN-g-BN hybrids are fabricated by a self-crosslinking reaction of cyano groups (-CN) from BN-CN and PEN-Ph. The fabricated PEN-g-BN hybrids are confirmed through FT-IR, UV-Vis, SEM and gel content measurements. The PEN-g-BN hybrids demonstrate excellent thermal resistance with their glass transition temperature (T_g) and decomposition temperatures (T_d) being higher than 235 °C and 530 °C, respectively. Additionally, the thermal conductivity of the prepared PEN-g-BN hybrids is up to 0.74 W/(m·k), intensifying competitiveness of PEN-g-BN hybrids for applications at elevated temperatures.

An Immunosensor Based on Au-Ag Bimetallic NPs Patterned on a Thermal Resistant Flexible Polymer Substrate for In-Vitro Protein Detection

Nanosensors based on flexible polymers have emerged as powerful tools for next generation smart devices in the recent years. Here, we report a facile protocol to fabricate an immunosensor supported by a thermally resistant flexible polymer substrate (polyarylene ether nitrile, PEN). The immunosensor is a localized surface plasmon resonance (LSPR) optical sensor for in-vitro protein detection based on anti-body coated gold-silver bimetallic nanoparticles (Au-Ag NPs) immobilized on a PEN substrate. Plasmonic spectroscopy and morphological characterization show that the Au-Ag NPs essentially exhibit a more uniform size distribution and higher quality factors than those from single-component Au NPs. Furthermore, it should be noted that the robust PEN substrate in this nanosensor acts a flexible substrate to support Au-Ag NPs and immobilize the nanoparticles via quick thermal annealing at 290 °C. Thanks to these merits, a prostate-specific antigen (PSA) concentration as low as 1 ng/mL can be specifically discriminated via the prepared PEN/Au-Au NPs, which confirms that the protocol reported in this work can be readily adapted for the construction of various flexible immunosensors for different applications.

Achieving Secondary Dispersion of Modified Nanoparticles by Hot-Stretching to Enhance Dielectric and Mechanical Properties of Polyarylene Ether Nitrile Composites

Enhanced dielectric and mechanical properties of polyarylene ether nitrile (PEN) are obtained through secondary dispersion of polyaniline functionalized barium titanate (PANI-f-BT) by hot-stretching. PANI-f-BT nanoparticles with different PANI content are successfully prepared via in-situ aniline polymerization technology. The transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopic instrument (XPS) and Thermogravimetric analysis (TGA) results confirm that the PANI layers uniformly enclose on the surface of BaTiO₃ nanoparticles. These nanoparticles are used as functional fillers to compound with PEN (PEN/PANI-f-BT) for studying its effect on the mechanical and dielectric performance of the obtained composites. In addition, the nanocomposites are uniaxial hot-stretched by 50% and 100% at 280 °C to obtain the oriented nanocomposite films. The results exhibit that the PANI-f-BT nanoparticles present good compatibility and dispersion in the PEN matrix, and the hot-stretching endows the second dispersion of PANI-f-BT in PEN resulting in enhanced mechanical properties, crystallinity and permittivity-temperature stability of the nanocomposites. The excellent performances of the nanocomposites indicate that a new approach for preparing high-temperature-resistant dielectric films is provided.

Scalable Fabrication of Metallopolymeric Superstructures for Highly Efficient Removal of Methylene Blue

Metallopolymeric superstructures (MPS) are hybrid functional materials that find wide applications in environmental, energy, catalytic and biomedical-related scenarios, while their fabrication usually suffers from the complicated polymerization between monomeric ligands and metal ions. In this work, we have developed a facile one-step protocol to fabricate metallopolymeric superstructures with different morphology including nanospheres, nanocubes, nanorods, and nanostars for environmental remediation application. Specifically, we have firstly synthesized the amphiphilic block copolymers (BCP) bearing hydrophobic aromatic backbone and hydrophilic pendent carboxylic/sulfonic groups, which have been subsequently transformed into MPS via the metal ions mediated self-assembly in mixed solution of dimethylformamide (DMF) and H2O. Based on SEM, FTIR, XRD and XPS characterization, we have revealed that the fine morphology and condensed structures of MPS can be modulated via the metal ions and BCP concentration, and the obtained MPS can be employed as efficient adsorbents for the removal of methylene blue with maximum adsorption capacity approaching 936.13 mg/g.

Benzoxazine Containing Fluorinated Aromatic Ether Nitrile Linkage: Preparation, Curing Kinetics and Dielectric Properties

Benzoxazine containing fluorinated aromatic ether nitrile linkage (FAEN-Bz) had been synthesized from 2,6-dichlorobenzonitrile, 4,4'-(hexafluoroisopropylidene)diphenol (bisphenol AF), 3-Aminophenol, formaldehyde, phenol by condensation polymerization and Mannich ring-forming reaction. Structures of the monomer were verified by Proton NMR spectrum (1H-NMR) and Fourier transform infrared spectroscopy (FTIR). Curing behaviors and curing kinetics of designed monomers were investigated and discussed. The activation energy was calculated and possible polymerization mechanisms were also proposed. Then, properties of cured polymers including crosslinking degrees, thermal decomposition, surface wettability and energy, and dielectric properties were studied and discussed. Additionally, programmed integral decomposition temperature (IPDT) was also used to evaluate the thermal stability of final polymers. Results indicated that the incorporation of benzoxazine and nitrile resulted in increased thermal stability and char yields. Moreover, the surface wettability and dielectric properties of poly(FAEN-Bz) can be easily controlled by tuning the curing temperatures and time.

Polyethylenimine Assisted Bio-Inspired Surface Functionalization of Hexagonal Boron Nitride for Enhancing the Crystallization and the Properties of Poly(Arylene Ether Nitrile)

Semi-crystalline poly(arylene ether nitrile) (PEN) has exhibited remarkable potential in various fields. However, the inherent drawbacks of PEN such as slow crystalline rate and low crystallinity limit its further development. To alleviate this problem, the choice of nanofiller as nucleation agent and the interfacial compatibility between nanofiller and PEN matrix are two momentous factors that need to be considered. Accordingly, in this work, functionalized hexagonal boron nitride (h-BN@(PDA+PEI)) was successfully synthesized via polyethylenimine (PEI) assisted bio-inspired surface functionalization, and then homogeneously dispersed in the PEN resin using solution casting method to obtain functional polymer nanocomposite films with strengthening the crystallization behavior, mechanical and dielectric properties. Various testing methods including differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray diffraction (XRD), and polarizing microscope (POM) were applied to intricately analyze the effect of h-BN@(PDA+PEI) on the crystallization behavior of PEN composites. The testing results certificated that the h-BN@(PDA+PEI) can effectively improve the crystallinity (from 6.56% to 14.90%), and the spherulite size of PEN was reduced while the nucleation density of nanocomposites was raised. Furthermore, the non-isothermal crystallization kinetics demonstrated that 2 wt% h-BN@(PDA+PEI) could significantly reduce the cold crystallization temperature (T_p) and the crystallization activation energy (E_a) (from 359.7 KJ/mol to 292.8 KJ/mol), while it improved the crystallization rate (K_c) of PEN. In addition, the mechanical and dielectric properties of nanocomposite films were also reinforced to further broaden the application of semi-crystalline PEN. Therefore, the h-BN@(PDA+PEI) can function as an effectual nucleating agent and enhance the performance of PEN.

Polyarylene ether nitrile and boron nitride composites: coating with sulfonated polyarylene ether nitrile

Boron nitride (BN) coated with sulfonated poly-arylene ether nitrile (SPEN) (BN@SPEN) was used as additive to enhance the thermal conductivity of polyarylene ether nitrile. BN@SPEN was prepared by coating BN micro-platelets with SPEN through ultrasonic technology combined with the post-treatment bonding process. The prepared BN@SPEN was characterized by FTIR, TGA, SEM and TEM, which confirmed the successful coating of BN micro-platelets. The obtained BN@SPEN was introduced into the PEN matrix to prepare composite films by a solution casting method. The compatibility between BN and PEN matrix was studied by using SEM observation and rheology measurement. Furthermore, thermal conductivity of BN@SPEN/PEN films were carefully characterized. Thermal conductivity of BN@SPEN/PEN films was increased to 0.69 W/(m⋅K) at 20 wt% content of BN@SPEN, having 138% increment comparing with pure PEN.

Synthesis and Photoinduced Anisotropy of Polymers Containing Nunchaku-Like Unit with an Azobenzene and a Mesogen

A series of polymers containing nunchaku-like unit with an azo chromophore and a mesogen group was successfully prepared and photoinduced anisotropy of the obtained polymers was minutely investigated. Firstly, monomers containing nunchaku-like unit with an azo chromophore and a mesogen group linked by flexible group were synthesized. The structure of the monomers was confirmed via NMR COSY spectra. Subsequently, the obtained monomers were polymerized into corresponding polymers through RAFT polymerization. The prepared polymer samples were characterized through NMR, FTIR, gel permeation chromatography (GPC), and UV-vis testing while the thermal properties of the samples were investigated through differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) measurements. The photoinduced isomerization of the polymers, which was researched in situ via measuring UV-vis spectra of the polymer solutions and spin-coated films under irradiation with 450 nm light or putting in darkness, demonstrated the rapid trans-cis-trans isomerization of the polymers. When irradiated with a linearly polarized light, significant photoinduced birefringence and dichroism were observed, suggesting photoinduced isomerization of azobenzene can drive orientation of mesogen in the system. This study blazes a way to design the optical materials with light-controllable birefringence and dichroism.

Polyarylene Ether Nitrile and Barium Titanate Nanocomposite Plasticized by Carboxylated Zinc Phthalocyanine Buffer

Barium titanate (BT) and polyarylene ether nitrile (PEN) nanocomposites with enhanced dielectric properties were obtained by using carboxylatedzinc phthalocyanine (ZnPc-COOH) buffer as the plasticizer. Carboxylated zinc phthalocyanine, prepared through hydrolyzing ZnPc in NaOH solution, reacted with the hydroxyl groups on the peripheral of hydrogen peroxide treated BT (BT-OH) yielding core-shell structured BT@ZnPc. Thermogravimetric analysis (TGA), transmission electron microscopy (TEM), TEM energy dispersive spectrometer mapping, scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and Fourier transform infrared (FTIR) demonstrated successful preparation of BT@ZnPc. The fabricated BT@ZnPc was incorporated into the PEN matrix through the solution casting method. Rheological measurements demonstrated that the ZnPc-COOH buffer can improve the compatibility between BT and PEN effectively. With the existence of the ZnPc-COOH buffer, the prepared BT@ZnPc/PEN nanocomposites exhibit a high dielectric constant of 5.94 and low dielectric loss (0.016 at 1000 Hz). BT@ZnPc/PEN dielectric composite films can be easily prepared, presenting great application prospects in the field of organic film capacitors.

Assessing the Critical Multifunctionality Threshold for Optimal Electrical, Thermal, and Nanomechanical Properties of Carbon Nanotubes/Epoxy Nanocomposites for Aerospace Applications

Epoxy composites are widely used in primary aerospace structures, where high impact damage properties are necessary. However, challenges appear when multiple functionalities, including electrical and thermal conductivity, are needed in parallel with increased mechanical properties. The current study aims at the assessment of a critical concentration of multiwalled carbon nanotubes (MWCNTs), incorporated in epoxy resin, which will indicate a threshold for optimal electrical, thermal and mechanical properties. For the evaluation of this optimal concentration, electrical conductivity, thermal stability and nanomechanical properties (Young modulus and nanohardness) have been assessed, for epoxy nanocomposites with 0 to 15 parts per hundred resin per weight (phr) MWCNTs. Percolation theory was applied to study the electrical conductivity for different contents of MWCNTs in the epoxy nanocomposite system. Thermogravimetric analysis was employed for the assessment of the epoxy composites’ thermal properties. Nanohardness and elastic modulus were measured, and the hardness versus modulus index was calculated. Emphasis was given to the dispersion of MWCNTs in the epoxy matrix, which was assessed by both microscopy techniques and X-ray micro–computed tomography. A correlation between the optimum dispersion and MWCNTs content in terms of electrical conductivity, thermal stability, and nanomechanical properties revealed a threshold concentration at 3 phr, allowing the manufacturing of aerospace structures with multifunctional properties.

Preparation of Sulfonated Poly(arylene ether nitrile)-Based Adsorbent as a Highly Selective and Efficient Adsorbent for Cationic Dyes

In this work, a highly selective and efficient polymer adsorbent inspired by a water-soluble sulfonated poly(arylene ether nitrile) (SPEN) was successfully synthesized. Due to the distinct structure of functional carboxyl, sulfonic acid and rigid benzene rings, a facile aluminium (III) ions crosslinking method was employed to fabricate the SPEN-based adsorbents (SPEN-Al). Among the three adsorbents, SPEN-Al-2 exhibited superior adsorption capacities with uniform morphology. Subsequently, the SPEN-Al-2 was selected as the adsorbent for three cationic dyes (rhodamine B (Rh B), neutral red (NR), methylene blue (MB)) and three anionic dyes (orange G (OG), methyl orange (MO), acid fuchsin (AF)), respectively, demonstrating that the adsorbent possessing excellent selectivity toward cationic dyes. Moreover, the dye's adsorption selectivity of SPEN-Al-2 was further certificated in a binary cationic-anionic dyes mixtures (MB/OG and MB/MO) system. Taking MB as a dye model, a series of factors (contact time, concentration, temperature and pH) and adsorption models were systematically investigated in dye adsorption experiments. Results indicated that the adsorption was endothermic and the maximum adsorption capacity of SPEN-Al-2 could reach up to 877.5 mg/g; pseudo-second-model and Langmuir model were fitted to the adsorption kinetics and equilibrium isotherm, respectively, manifesting that SPEN-Al adsorbent was promising in the dyes removing field.