Preparation and dielectric properties of poly(arylene ether nitrile) containing carboxyl groups/carbon nanotubes composites

Poly(arylene ether nitrile) (PEN)/carbon nanotubes (CNTs) hybrid films were prepared with different CNTs content (0–2.5 wt%) by solution blending method. The dispersion of CNTs can be improved by the functional groups, which is attributed to the pendent carboxyl groups on the PEN matrix itself. Namely, the carboxyl groups on the side-chain of PEN react with the hydroxyl groups of CNTs. Scanning electron microscope showed that the dispersion of the CNTs was enhanced by the carboxyl groups on the PEN. Differential scanning calorimetry and thermal gravimetric analyses experiments showed that the hybrid films exhibit a good thermal stability. The dielectric constant of the hybrid film with 2.5 wt% CNT content reaches 27 compared to 4 at pure PEN at 1 kHz. From room temperature to 150 °C, temperature variation over the range has a slight effect on the dielectric properties of the hybrid films. The dielectric constant of the hybrid film with 2.5 wt% CNT content reaches 30 compared to 5 at pure PEN at 150 °C. The results illustrate that the PEN/CNTs hybrid films are good dielectric materials, which is favorable for many industrial applications.     

低介电耐温改性空心SiO2填充含氟聚芳醚腈复合材料的制备及性能

开发低介电常数、低介电损耗和同时兼具耐温、高力学强度的聚合物介电材料对于满足5G领域的高性能介电材料具有重要的研究意义。采用含氟1H,1H,2H,2H-全氟取代癸基三乙氧基硅烷（PTES）对空心SiO₂纳米粒子（HS）进行表面改性,并基于含氟聚芳醚腈共聚物（PEN-F）,分别以流延法和相转换法制备了两种PTES改性HS填充的PEN-F复合材料（HS@PTES/PEN-F）。采用FTIR和1H NMR证实了PEN-F共聚物的成功合成;通过FTIR、TGA和XPS等技术手段表征了PTES改性的HS结构和形貌;同时研究了HS@PTES/PEN-F复合材料的介电性能、力学强度和热稳定性等。研究结果表明,经PTES改性后的HS纳米粒子在PEN-F基体树脂中具有较好的分散性与界面相容性。在介电性能方面,当改性SiO₂纳米粒子填充含量为7wt%时,通过流延法制备的HS@PTES/PEN-F复合膜在1 kHz时介电常数达2.88,介电损耗为0.0198;通过相转换法制备的HS@PTES/PEN-F复合膜在1 kHz时介电常数达1.19,介电损耗为0.0043...     

Preparation and characterization of poly (arylene ether nitrile)/copper phthalocyanine composites via sintering treatment

In this work, copper phthalocyanine (CuPc) polymers of excellent electrical conductivity were successfully prepared via a high temperature sintering procedure, the chemical structures and morphology of obtained CuPc polymers were characterized by FTIR and SEM, respectively. Thereafter, CuPc/polyarylene nitrile ethers (PEN) composite films were prepared via solution-casting method. The obtained films show excellent thermal, mechanical and dielectric properties due to the good dispersion and compatibility of conductive CuPc polymers in PEN matrix, which was confirmed by the SEM characterization.     

New fluorinated poly(ether sulfone imide)s with high thermal stability and low dielectric constant

A new aromatic diamine monomer with four pendant trifluoromethyl groups, 2,2′-bis{3-[3,5-di(trifluoromethyl)phenyl]-4-[4-amino-phenoxy]phenyl}sulfone (3), was successfully synthesized through free-radical substitution, Suzuki coupling and nucleophilic substitution reactions using bis(4-fluorophenyl)sulfone and N-bromosuccinimide as starting materials. Then it was employed to prepare a series of fluorinated poly(ether sulfone imide)s (PESIs 5a–c) with various commercial aromatic dianhydrides via a one-step high-temperature polycondensation. These polymers could be easily dissolved in some strong polar organic solvents, such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide, and N,N-dimethylformamide, chloroform, dichloromethane and tetrahydrofuran at room temperature. Flexible and transparent films can be obtained easily by solution casting. They had high thermal stability and didn't show significant weight loss up to temperature of approximately 530 °C in nitrogen and air atmospheres. They also revealed low dielectric constants with the values in the range of 2.74–2.90 at 1 MHz measured for their capacitance.     

酚酞型聚芳醚腈砜的合成与性能研究

以酚酞、２，６二卤苯甲腈、４，４’，二氯二苯砜和４，４’，二羟基二苯砜为主要原料进行共缩聚反应，合成了酚酞型聚芳醚腈砜（ＰＰ－ＰＥＮＳ）。采用红外光谱、热分析等方法对共聚物的结构、热氧稳定性和玻璃化转变温度进行了表征，并对酚酞结构单元含量和腈基含量对聚芳醚腈砜性能的影响进行了讨论     

Decoration of reduced graphene oxide with dandelion-like TiO2 and their dielectric properties in poly(arylene ether nitriles) composites

Novel dandelion-like titanium oxide (TiO₂) decorated reduced graphene oxide (rGO@TiO₂) hybrids were obtained by a one-step solvent-thermal reduction of GO and tetrabutyl titanate simultaneously. The hybrids were used as a novel filler for high performance poly(arylene ether nitriles) (PEN) composites. The thermal stability and morphological properties of the PEN composites were, respectively, investigated by the thermo gravimetric analysis and scanning electron microscope, aiming at examining the effect of surface decoration on the dispersion of rGO@TiO₂ in PEN matrix. The results indicated that the rGO@TiO₂ present better dispersion in the PEN matrix. Meanwhile, the derived composite films exhibited high thermal stability with initial decomposition temperatures (T _id ) in the range of 477–487 °C. DSC curves showed that the glass transition temperatures were in the range of 219–227 °C. Moreover, all of the composite films also showed excellent flexibility and mechanical properties. The tensile modulus and strength were increased about 4 and 6 % with 5 wt% rGO@TiO₂ loading, respectively. More importantly, for 30 wt% rGO@TiO₂ reinforced PEN composite film, the dielectric permittivity dramatically increased from 3.8 to 81 at 1 kHz.     

Preparation and characterization of poly(arylene ether nitriles)/glass fibers/BaTiO3 ternary composites

Poly(arylene ether nitriles) (PEN) copolymers PEN (HQ/RS) was synthesized using 2,6-dicholorobenzonitrile (DCBN) with equal molar of hydroquinone (HQ) and resorcin (RS). Composites of PEN reinforced by glass fiber (GF) and nanometer-sized BaTiO₃ particle were prepared through melt blending. Both mechanical and thermal properties of the composites were found improved with the increase of GF as well as BaTiO₃ contents. For PEN/GF/BaTiO₃ ternary composites, the best mechanical properties were found when the content for GF and BaTiO₃ is 8 wt.% and 22 wt.%, respectively. The fractured surfaces of PEN/BaTiO₃ composites were examined with SEM and show a characteristic of ductile fracture. The heat distortion temperature (HDT) of 35 wt.% GF reinforced composite is 241 °C, nearly an increase ca. 100 °C compared to that of the pristine resin.     

Tailoring of thermal and dielectric properties of LDPE-matrix composites by the volume fraction,density, and surface modification of hollow glass microsphere filler

Hollow glass microsphere (HGM) filled low-density polyethylene (LDPE) composites were prepared, and the effects of density, content, and surface modification of HGM on the thermal and dielectric properties of the composites were investigated. It is found that the thermal conductivity of the composites decreases with increasing HGM content or decreasing HGM density. At the same HGM content and density, the composites filled with suitable amount of silane coupling agent (KH570) modified HGM exhibit higher thermal conductivity than unmodified-HGM filled composites. The dielectric constant at 1 MHz of the composites also decreases with increasing HGM content or decreasing HGM density, but their dielectric loss increases with increasing HGM content or increasing HGM density. By modifying the surface of HGM with suitable amount of KH570, the dielectric constant and loss at 1 MHz of the composites can be decreased at the same time. The results of microwave dielectric properties of the composites indicate that the dielectric constant decreases with increasing HGM content or decreasing HGM density, the quality factor (Q × f) decreases with increasing HGM content or increasing HGM density, but both dielectric constant and quality factor are slightly affected by the surface modification of HGM. Due to lower intrinsic thermal conductivity and dielectric constant but higher dielectric loss of HGM than LDPE, the thermal conductivity and dielectric properties of the composites can be controlled with adding HGM and varying its volume fraction. The surface modification of HGM improves the interface contact between HGM and LDPE in the composites, which is confirmed by the SEM observation, and thus the heat conduction and dielectric properties at low frequency are improved. Based on calculated thermal conductivity and dielectric constant of HGM, the experimental trends of thermal conductivity and dielectric constant at 1 MHz of the composites are analyzed by using different models, including typical models for particles-filled composites and special models developed for hollow microsphere filled composites. The results from suitable models show close correlation with the experimental values.     

9,10-Diphenylanthracene-containing poly(arylene ether sulfone)s with improved glass transition temperature and photocrosslinking properties

In this study, novel poly(arylene ether sulfone)s containing 9,10-diphenylanthracene units were synthesized and their thermal and optical properties were investigated. This new bisphenol monomer, 9,10-bis(4-hydroxyphenyl)anthracene, was facially synthesized in two steps and showed similar reactivity for SNAr reactions as other bisphenol monomers, such as bisphenol A. The introduction of an anthracene unit to poly(arylene ether sulfone)s can obviously improve glass transition temperature and retain good solubility and high decomposition temperatures. The glass transition temperature of poly(arylene ether sulfone) reached up to 265 °C when the bisphenol A was entirely substituted by bis(4-hydroxyphenol)anthracene. These polymers are soluble in chloroform, N,N-dimethylformamide and N-methyl-2-pyrrolodone and can be film-formed through spin-coating. Interestingly, anthracene units endowed these polymers with photocrosslinkable properties and further improved their thermal stability.     

Synthesis and dielectric properties of polyarylene ether nitriles with high thermal stability and high mechanical strength

A series of polyarylene ether nitriles were synthesized by the nucleophilic aromatic substitution polymerization of 2, 6-dichlorobenzonitrile with various bisphenol monomers. Owing to the different structural units, the derived copolymers showed different glass transition temperatures in the range of 166–260 °C. Moreover, they all showed good film-forming properties and high mechanical strength ranging from 75 MPa to 117 MPa, and also exhibited high thermal stability with the 5% weight loss temperatures ranging from 373 °C to 498 °C. Furthermore, both the dielectric constant and dielectric loss were found to be relatively stable with respect to temperature before the turning point temperature, which is very near to the glass transition temperature.     

Flexible polyarylene ether nitrile containing pendant carboxyl groups/Eu(III) fluorescent films with high thermal stability and mechanical strength

A series of flexible and transparent polyarylene ether nitrile with pendant carboxyl groups/Eu(III) fluorescent films were successfully prepared, and characterized by scanning electron microscopy, energy-dispersive spectroscopy, thermogravimetric analysis, tensile test, ultraviolet–visible absorption and fluorescence spectroscopy. The results showed that the films possess high thermal stability (5% weight loss temperatures over 425 °C) and high mechanical strength (tensile strengths exceeding 90 MPa). Furthermore, all the films exhibit a relatively high transmittance in the visible region, and also show an excellent macroscopic flexibility, so that they can be easily bent and curled. This is mainly attributed to the superior performance of the polymer matrix. The photoluminescence results indicated that the films emit an intense red light at 617 nm under ultraviolet excitation, which is attributed to the ⁵D₀ → ⁷F₂ transitions of Eu(III) ions.     

钛酸钡-氮化硼/聚间苯二甲酰间苯二胺复合电介质的制备与导热性能

选用聚多巴胺(PDA)和十八烷基异氰酸酯分别改性钛酸钡纳米线(BTW)和氮化硼纳米片(BNNSs)来构筑D@BTW-fBNNSs高介电导热填料.研究了D@BTW-fBNNSs高介电导热填料对芳香族聚酰胺(PMIA)基复合电介质介电性能、击穿强度和导热性能的影响.结果表明:随着复合电介质中D@BTW-fBNNSs含量的增...     

Mechanical properties of high strength and high toughness metallic filament composites with epoxy and poly(ether ether ketone) matrices

High strength and high toughness metallic filament was produced by glass-coated melt spinning. The mechanical properties of the composite consisting of the filaments uniaxially aligned in brittle epoxy resin, ductile epoxy resin with plasticizer and poly(ether ether ketone) matrices were investigated. It was found that the Young's modulus (E _c) and tensile strength (,_cu) of the composite consisting of uncoated filaments in brittle epoxy matrix were higher than those predicted by a linear function of the filament content (Vf), and the filaments fractured tightly in contact with the matrix. On the other hand, no improvement of the mechanical properties of the composite consisting of glass-coated filaments in brittle epoxy matrix was detected, due to the weak interfacial force between metallic filaments and the coating glass. The composite consisting of filaments in a ductile matrix was a high toughness material with a long range of plasticity deformation, and the experimental values ofE _c and _cu against V_f agreed with the simple law of mixtures.     

新型改性聚芳醚腈酮耐温水分散涂料的研制

通过对新型耐高温聚合物杂萘联苯聚芳醚腈酮(PPENK)中的氰基转化为亲水性基团羧基或酰胺基,系统地研究了改性聚芳醚腈酮(HPPENK)在耐高温水性涂料中的应用,考察了不同氰基转化率的HPPENKa(55.82%)、HPPENKb(78.23%)和HPPENKc(93.82%)树脂作为主要成膜物质的水分散体的性能,其中HPPENKc具有较好的分散稳定性和良好的成膜性,漆膜附着力(划圈法)为一级,铅笔硬度＞6H,能耐受300℃(24h),对水和有机溶剂有一定耐受能力.甄选了六甲基醚化三聚氰胺树脂(HMMM)、环氧氯丙烷(ECH)、三乙醇胺、甘油、乙二胺等作为HPPENK的交联剂,其中HMMM和环氧氯丙烷具有较好的交联效果,外加乳化剂采用司班和吐温的复配取得较好的乳化效果.同时,通过考察了乳化剂、分散剂、中和剂、附着力促进剂等涂料助剂的选择及用量,提出了水分散体配方.     

含芴聚芳醚酮对BMI树脂增韧改性的研究

采用将含芴聚芳醚酮(PFEK)溶解于3,3’-二烯丙基双酚A,低温下加入4,4’-二氨基二苯甲烷双马来酰亚胺进行熔融共聚,再高温固化的方式,制备了含芴聚芳醚酮增韧的双马来酰亚胺树脂。结果表明:PFEK树脂的加入对复合材料的固化行为没有影响,PFEK树脂的加入量在7.5%~10.0%之间复合材料发生相反转,复合材料具有相分离结构;当PFEK的加入量为10.0%时,复合材料的弯曲强度和抗冲击强度由无PFEK树脂时的110.2MPa与9.0kJ/m2提高到148.7MPa与14.6kJ/m2,PFEK树脂的加入提高了复合材料的耐温性能。     

质子交换膜用部分含氟磺化聚芳醚的合成与性能研究

通过直接磺化的方法,合成了一种部分含氟的磺化聚芳醚.由于特殊单体结构的设计,在聚合物主链上引入甲基取代基,对聚合物主链进行保护.用氯磺酸直接磺化方法在聚芳醚侧基上引入磺酸功能基,实现了聚合物磺化结构的可控定位合成,得到了稳定性较好的磺化聚芳醚.用溶液浇膜法制备了质子交换膜,研究了膜的各种性能.这种膜具有较高的导电性、吸水性和好的抗水解性、热稳定性.由于特殊结构的设计和部分氟的引入,这种膜的抗氧化性有显著的提高.     

Synthesis and characterization of novel photoactive poly(arylene ether ketone) with azobenzene pendants

A novel azobenzene-functionalized poly(arylene ether ketone) (azo-PAEK) with azo moieties on the pendants was prepared by post-esterification reaction of acid-containing poly(arylene ether ketone) (acid-PAEK) with 4-((4-nitrophenyl)diazenyl)phenol (NAP). DSC and TGA measurements indicate the azo-PAEK has high glass transition temperature of 152 °C and good thermal stability with 5% weight loss at 319 °C. Irradiated by 360 nm UV light, the azo-PAEK shows a significant photoisomerization effect. Under the illumination of linearly polarized laser beam, significant surface-relief-gratings (SRGs) with the surface modulation depth of 37 nm were fabricated rapidly on the azo-PAEK film.     

Graphene/poly(vinylidene fluoride) composites with high dielectric constant and low percolation threshold

In aiming to obtain highly flexible polymer composites with high dielectric performance, graphene/poly(vinylidene fluoride) (PVDF) composites with a multi-layered structure were proposed and prepared. Graphene sheets were prepared by reducing graphene oxide using phenylhydrazine, which could effectively alleviate aggregation of the graphene sheets. A two-step method, including solution casting and compression molding, was employed to fabricate the graphene/PVDF composites. The composites showed an alternative multi-layered structure of graphene sheets and PVDF. Due to their unique structure, the composites had an extremely low percolation threshold (0.0018 volume fraction of graphene), which was the lowest percolation threshold ever reported among PVDF-based polymer composites. A high dielectric constant of more than 340 at 100?Hz could be obtained within the vicinity of the percolation threshold when the graphene volume fraction was 0.00177. Above the percolation threshold, the dielectric constant continued to increase and a maximum value of as high as 7940 at 100?Hz was observed when the graphene volume fraction was 0.0177.