Low dielectric permittivity and high thermal stability composites based on crosslinkable poly (arylene ether nitrile) and hollow glass microsphere

Crosslinkable poly (arylene ether nitrile)/hollow glass microsphere (PEN/HGM) composites with relative low dielectric permittivity and high thermal stability were prepared by a solution mixing and thermal compression method. For achieving this purpose, HGM were tight embedded in network, which were formed by crosslinking reaction of PEN end-capped with phthalonitrile. Compared to pure PEN, the dielectric constant of the resulting composite with 15 wt% of HGM reduced from 4.1 to 2.7 at 100 kHz, and the dielectric loss decreased from 2.0 × 10^?2 to 0.8 × 10^?2 at 100 kHz. Furthermore, the as-prepared composites showed significant enhancement in glass transition temperature (increased by 64 °C) and onset thermal degradation temperature (increased by 41 °C). Therefore, such composites were expected to find their applications area such as integrated circuit where needs low dielectric constant, low dielectric loss and high thermal stability.     

Influence of the polymer backbone structure on the properties of aromatic ionomers with pendant sulfobenzoyl side chains for use as proton-exchange membranes

Six different ionomers having various aromatic polymer backbones with pendant 2-sulfobenzoyl side chains were prepared by nucleophilic aromatic substitution reactions of lithium 2,6-difluoro-2'-sulfobenzophenone with 4,4-biphenol, 2,7-dihydroxynaphthalene, 4,4-isopropylidenediphenol, 4,4-dihydroxydiphenyl ether, 4,4'-thiodiphenol, and 4,4'-thiobisbenzenethiol, respectively, to produce four poly(arylene ether)s, one poly(arylene ether sulfide), and one poly(arylene sulfide). Mechanically tough proton-exchange membranes with ion-exchange capacities in the narrow range from 1.9 to 2.3 mequiv/g were cast from the high-molecular-weight ionomers, and subsequently investigated with respect to their structure-property relationships. Glass transitions were only detected for ionomers in the sodium salt form, and increasing glass-transition temperatures (Tg) were found to give higher thermal decomposition temperatures. Analysis by small-angle X-ray scattering indicated that the ionic clustering was promoted for ionomers with flexible polymer backbones and low Tg values. The proton conductivity of the membranes at 80 °C under fully humidified conditions was found between 0.02 and 0.2 S/cm and appeared to depend primarily on the Tg.     

Effect of multiwalled carbon nanotubes on the crystallization and dielectric properties of BP-PEN nanocomposites

In this work, polymer-based nanocomposite films formed from biphenol poly(arylene ether nitrile) (BP-PEN) and multiwalled carbon nanotubes (MWCNTs) were successfully prepared by the solution casting method combined with continuous ultrasonic dispersion technology. The micromorphology, thermal, mechanical and dielectric properties of the nanocomposite films were investigated in detail. Non-isothermal crystallization behavior studies indicate that the presence of MWCNTs enhances the crystallization of BP-PEN in the nanocomposites, which is consistent with the XRD analysis. Most importantly, it could be observed that the film containing 0.8 wt% MWCNTs reached the maximum crystallinity. Although, incorporation of MWCNTs did not obviously increase the mechanical of the films, all the nanocomposite films still exhibited excellent mechanical strength. The SEM micrographs of the nanocomposite films showed that the MWCNTs were uniformly coated by BP-PEN crystals, and indicating significantly improved nucleation ability of MWCNTs for polymer crystallization.     

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.     

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.     

一种新型含氟含芴聚芳醚酮质子交换膜的合成和表征

以双酚芴、十氟联苯和磺化二氟酮为单体,合成磺化含氟聚芴醚酮(Sulfonated-fluo-rinated fluorene-containing poly(arylene ether ketone)s,SFPEEK).SFPEEK可溶于极性有机溶剂,具有较高的黏度,易于浇铸形成柔韧透明的薄膜.用其制成的质子交换膜表现出良好的热稳定性和抗水解、抗氧化性能.在相同测试条件下,SFPEEK膜具有与杜邦公司Nation 117膜相当的质子电导率,同时,具有比Nafion 117更好的耐甲醇渗透性能.直接甲醇燃料电池(DMFC)单池测试表明,放电到0.2 V时,用SFPEEK膜制备的单池电流密度可达66 mA/cm2,电池性能优于相同条件下用Nafion117膜组装的单池(电流密度60 mA/cm2).     

含苯并噁嗪-双邻苯二甲腈树脂及其复合材料的制备与性能

本工作通过以4-氨基苯氧基邻苯二甲腈,双酚A,甲醛为原料,二氧六环为溶剂,甲苯为脱水剂合成了含苯并噁嗪-双邻苯二甲腈,采用腈基二元胺为交联剂在160oC制备预聚物树脂,经丙酮溶解并分散碳纳米管再浸渍玻璃布获得预浸料,经热压成型后热处理制得玻璃纤维/碳纳米管/双邻苯二甲腈树脂复合材料,详细研究了树脂的合成及其固化反应.该类树脂及复合材料具有较好的力学性能,热稳定性能,碳纳米管的加入可以协同增强玻纤复合材料,同时改善其导电性,并赋予复合材料新的吸波特性。     

Facile preparation of the novel castor oil-based benzoxazine–urethane copolymer with improved high-frequency dielectric properties

The novel star shaped benzoxazine-co-urethane prepolymers are first synthesized from the natural resource castor oil, hydroxyl terminated benzoxazine and diisocyanate through the facile one-pot formulation method. Then the cured benzoxazine copolymers can be obtained by the ring-opening polymerization of oxazine groups of the prepared prepolymers. Both hexamethylene diisocyanate and 4,4′-methylenediphenyl diisocyanate are employed as aliphatic and aromatic diisocyanate, respectively, to clarify their effects on the chemical structure and high-frequency dielectric properties of copolymers. In comparison with the pure polybenzoxazine, the copolymer films occupy the improved high-frequency dielectric properties owing to the introduction of three branching aliphatic castor oil, leading to the reduction of molecular polarity and the improvement of free volume. It should be noted that the aliphatic diisocyanate not only decreases the polarity of the copolymer, but also enhances the intermolecular interaction and intermolecular entanglement between castor oil and benzoxazine for the copolymers. Accordingly, the aliphatic diisocyanate based poly(benzoxazine-co-urethane) occupies the minimum high-frequency dielectric constants (2.94, 5 GHz; 2.96, 10 GHz) and relatively high glass transition temperature (220 °C). Therefore, this work not only provides a simple path for improving high-frequency dielectric properties of benzoxazine, but also gives some insight into the effects of diisocyanates on the formation and high-frequency dielectric properties of poly(benzoxazine-co-urethane)s.     

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     

Effect of magnetite bridged carbon nanotube/graphene networks on the properties of polyarylene ether nitrile

We report the fabrication and properties of polyarylene ether nitrile (PEN) nanocomposite with 3D carbon nanotubes/graphene sheets network (Fe₃O₄-CNT/GS) bridged by magnetite. The Fe₃O₄-CNT/GS is firstly fabricated by one-step solvothermal method after the synthesis of phthalonitrile functionalized CNT (CNT-CN) and GO (GO-CNT). Fe₃O₄-CNT/GS is characterized by XPS and XRD, while the 3D frame of it is confirmed by SEM observation. Then, the obtained Fe₃O₄-CNT/GS is introduced into phthalonitrile end-capped polyarylene ether nitrile (PEN-Ph) to prepare the composites by solution-mixing assembly and solution casting method. Finally, the obtained PEN based nanocomposites are further treated at 320 °C to improve the properties of the composites. To study the effect of Fe₃O₄-CNT/GS on the PEN-Ph, the micro-morphologies, mechanical, thermal and dielectric properties of the obtained (Fe₃O₄-CNT/GS)/PEN nanocomposites films are investigated. Besides, the influence of the Fe₃O₄-CNT/GS content and the heat-treatment on the properties of the PEN composites are also investigated. The results show that Fe₃O₄-CNT/GS can improve the dielectric properties and maintain good mechanical properties of PEN composite simultaneously.     

Effect of nitrile-functionalization and thermal cross-linking on the dielectric and mechanical properties of PEN/CNTs–CN composites

In this study, a novel series of composite films consisting of nitrile-functionalized carbon nanotubes (CNTs–CN) and poly(arylene ether nitriles) (PEN) were successfully fabricated by the tape-casting method. The –CN groups in PEN chains and the phthalonitrile groups on CNTs–CN formed the thermally stable triazine rings by thermal cross-linking reaction in the presence of diamino diphenyl sulfone, which was characterized by Fourier transform infrared spectroscopy. The result indicated that the chemical cross-linking reaction occurred accompanied by the emergence of a new absorption peak at 1,361 cm^?1. Besides, the effect of cross-linking on the morphology, thermal stability, mechanical and dielectric properties of the PEN/CNTs–CN was investigated. The SEM images showed that the phase interface between surface modified CNTs and PEN matrix was indistinct, and the surface modified CNTs presented a better dispersion behavior in PEN matrix. The mechanical properties of the processed films were improved substantially compared with the unprocessed films. Furthermore, the glass-transition temperature (T _g ) of composite films processed at 320 °C for 4 h (about 245 °C) was higher than that of composite films before thermal treatment (about 205 °C). The 5 % weight loss temperature of the composite films (processed at 320 °C for 4 h) increased by about 110 °C compared with the composite films (unprocessed). More importantly, by thermal cross-linking, the dielectric constant (ε) of composite films with 8 wt% CNTs–CN loading was increased from 31.8 to 33.9, and dielectric loss (tan δ) was decreased from 0.90 to 0.61 at 1 kHz.     

聚(芳基醚1,3,4-噁二唑)类聚合物的合成及表征

为改善芳香族聚噁二唑的加工性,合成了一种含噁二唑的双氟单体,将其与二酚单体进行溶液缩聚,得到一系列含有醚键与C(CH3)2,CCH3C6H5等官能团的新型聚(芳基醚1,3,4-噁二唑)(PEOD),其黏度达1.0 dL/g,噁二唑成环率达100%,并通过核磁氢谱(1H-NMR)和元素分析(EA)证实了其化学结构。通过热重分析(TGA)对PEOD的热稳定性进行了表征,结果表明,这些聚合物具有优良的热性能。通过溶解性试验表明PEOD能够溶解于三氯甲烷(CHCl3)、二氯甲烷(CH2Cl2)、四氢呋喃(THF)等有机溶剂,其溶解性比聚对苯撑噁二唑(p-POD)及对间苯噁二唑(p/m-POD)有了较大的改善。     

Preparation and dielectric properties of fullerene-doped polyarylene ether nitrile film

In order to obtain polymer films with low dielectric constant (≤2.0) and enhanced mechanical strength, fullerene-doped polyarylene ether nitrile (PEN) film was designed and prepared according to the following step. At first, fullerene and PEN were dissolved in toluene and N-methyl pyrrolidone, respectively, and the solutions were mixed together. The films were prepared by solution casting/solvent evaporation method on glass sheet. The morphology and thermal analysis of the films were characterized by visual & SEM observation and DSC & TGA test, respectively. The mechanical properties and dielectric properties of the films were also measured. The results showed that the dispersion of fullerene was largely dependent on the evaporation methods of the solvents. The glass transition temperature (Tg) and thermal decomposition temperature (Td) of PEN films were improved with the addition of fullerene. The dielectric constant sharply decreased from 4.0 to about 2.0 with the addition of fullerene. At the same time, the mechanical properties were improved, which might be caused by the physical entanglement of PEN chains with fullerenes. The lowest ε value (1.75 at 1 MHz) and the highest tensile strength (142.2 Mpa) were simultaneously obtained in samples containing 3 wt% fullerenes, which indicated it’s the optimal content of fullerene.     

新型聚芳醚酮离聚物膜材料的合成及结构表征

以二氯二苯甲烷和2,6-二甲基苯酚为原料合成了含有阻碍基团的双酚单体,用此双酚单体和1,3-二(4-氟苯甲酰基苯)在无水碳酸钾存在的条件下反应制得聚芳醚酮,然后用氯磺酸磺化,控制反应条件,使磺酸基团恰好进入苯环对位,制得新型结构的磺化聚芳醚酮。用DM SO溶解,倾于干净平整的玻璃板上制得无氟质子交换膜。     

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.     

具有多层结构的聚合物复合薄膜的介电和磁性能

采用旋涂法制备了 Fe3 O4/聚偏氟乙烯(PVDF)复合薄膜(A)、多壁碳纳米管(MWCNT)/PVDF复合薄膜(B)以及纯PVDF薄膜(P)。利用热压法制备具有3层结构的AAA、ABA及APA 复合薄膜。为了探究层状结构对复合薄膜介电和磁性能的影响,制备了单层膜A作为对比(厚度与AAA复合薄膜相同)。分别研究了薄膜的介电和磁性能。结果表明：由于界面效应,同等厚度的AAA复合薄膜较A膜而言具有较高的介电常数;以B和P薄膜替代AAA结构中间层薄膜后,其中ABA复合薄膜的介电常数高于AAA及APA复合薄膜,同时保持较低的介电损耗。对于磁性能,层状结构对复合薄膜的饱和磁化强度及矫顽力均无明显的影响,而ABA复合薄膜的饱和磁化强度高于AAA及APA复合薄膜,且ABA和APA复合薄膜的矫顽力增加。层状结构设计不仅能够调节复合材料的介电性能和磁性能,而且有利于不同纳米填料的分散,为制备多功能聚合物复合材料提供了一定的借鉴作用。     

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.     

The effect of zeolite L content on dielectric behavior and thermal stability of polyimide thin films

Zeolite L, with the ratio Si/Al?=?4, was prepared by hydrothermal method and used to obtain composite films based on a polyimide matrix having pendant carboxylic groups. The effect of zeolite L content on dielectric behavior and thermal stability of polyimide thin films was studied. The films were prepared by casting a suspension resulting from direct mixing of a poly(amic acid) (PAA) solution and zeolite L particles onto glass plates, followed by thermal imidization under controlled temperature conditions. The PAA was synthesized by solution polycondensation of a mixture of two diamines, 3,5-diaminobenzoic acid and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (molar ratio 1:3), with 4,4′-oxydiphthalic anhydride, using N-methyl-2-pyrrolidone as solvent. To improve the compatibility between organic and inorganic phases, the surface of zeolite particles was modified by treating with 3-aminopropyltriethoxysilane. The surface morphology of the composite films investigated by scanning electron microscopy showed good compatibility between filler and polymer matrix. The films were flexible, tough, and exhibited high-thermal stability, having the initial decomposition temperature above 450?°C. Dynamic mechanical analysis and dielectric spectroscopy revealed sub-glass transitions, γ and β, and an α relaxation corresponding to the segmental motions above the glass transition temperature. The values of the dielectric constant at 10?kHz and 200?°C were in the range of 3.3–4.2.     

质子交换膜材料磺化聚芳醚腈酮酮的合成及性能表征

用4-(4-羟苯基)二氮杂萘酮(DHPZ)、3,3′-二磺酸钠-4,4′-(4-氟苯甲酰基)苯(SDFKK)、2,6-二氯苯腈(DCBN)以及4,4′-(4-氟苯甲酰基)苯(DFKK),通过缩合共聚反应成功合成了一系列不同磺化度、高分子量的磺化聚芳醚腈酮酮(SPPENKKs).利用红外光谱(FT-IR)与核磁共振谱图(1H-NMR)证明了聚合物分子结构,利用热重分析仪(TGA)研究了氢型聚合物膜的耐热性能.以N-甲基吡咯烷酮为溶剂,用溶液涂敷法成功制备了具有良好韧性的SPPENKKs均质膜.利用乌氏粘度计测定聚合物的粘度,并研究了不同磺化度的聚合物膜的溶解性能、保水能力、热稳定性能、质子传导率等性能.     

Electrical and mechanical properties of poly(arylene disulfide)s derived from macrocyclic(arylene disulfide) oligomers

Poly(arylene disulfide)s were prepared by thermo-initialized ring-opening polymerization (ROP) of macrocyclic(arylene disulfide) oligomers. These macrocyclic oligomers were synthesized by catalytic oxidation of 4,4-oxybis(benzenethiol) with oxygen in the presence of a copper-amine catalyst. This is the first work to characterize and investigate the electrical and mechanical properties of the poly(arylene disulfide)s obtained via ring-opening polymerization. The surface resistance and volume resistance of the polyaromatic disulfides cured at 180–220°C were higher than 10¹⁴ ohm and 10¹⁶ ohm·cm, respectively. The results indicated that the as-made polymers exhibited superior dielectric properties. Both mechanical strength and electrical properties of these polymers varied according to ROP conditions. These properties demonstrated that the macrocyclic(arylene disulfide) oligomers derived from 4,4-oxybis(benzenethiol) could be used to produce thermally curing insulating material to substitute epoxy resins.