Fluorinated polyimide/POSS hybrid polymers with high solubility and low dielectric constant

A series of fluorinated polyimide/POSS hybrid polymers(FPI-4-FPI-16) were prepared via a facile synthetic route using 2,2'-bis(trifluoromethyl)benzidine, 4,4'-oxydiphthalic dianhydride and monofunctional POSS as starting materials. The hybrid polymers showed excellent solubility and film formation ability. Flexible and robust hybrid films could be conveniently obtained via solution-casting. The hybrid films demonstrated low dielectric constants and high thermal stability. Their dielectric constants were in the range of 2.47–2.92 at 1 MHz measured for their capacitance, and were tunable and decreased with an increase of POSS content. Their 10% weight loss temperatures were in the range of 539-591 ℃ and the weight residual at 800 ℃ ranged from 48% to 53% in nitrogen atmosphere. These hybrid films also possessed good mechanical properties and hydrophobic characteristics. This work could provide a potential strategy for the preparation of fluorinated polyimide/POSS hybrid polymers.     

Tailoring the Properties of Diels-Alder Reaction Crosslinked High-performance Thermosets by Different Bismaleimides

A series of Diels-Alder reaction cross-linked thermosets with recyclability and healability were prepared from furan-containing aromatic polyamide and bismaleimides with different chemical structures.The structures of synthesized bismaleimides were confirmed by 1 H nuclear magnetic resonance(1 H-NMR)spectroscopy;their reversible cross-linking with the furanic polyamide was further detected by 1 H-NMR technique and sol-gel transition behavior.The dynamic mechanical analysis and tensile test revealed the variable thermal and mechanical properties of thermosets cross-linked by different bismaleimides and with different molar ratios of maleimide group to furan group(Ima/fur).The tensile test also demonstrated that the better recyclability and solvent-assisted healability of thermosets cross-linked could be achieved by more flexible bismaleimides.This work is expected to provide valuable information for design of recyclable and healable high-performance thermosets with desired properties.     

SYNTHESIS AND CHARACTERIZATION OF ORGANO-SOLUBLE FLUORINATED POLYIMIDES FROM 4,4′-BIS(3-AMINO-5-TRIFLUOROMETHYLPHENOXY)-BIPHENYL AND VARIOUS AROMATIC DIANHYDRIDES

An aromatic diamine monomer, 4,4′-bis(3-amino-5-trifluoromethyl phenoxy)-biphenyl (TFBPDA), was synthesized via the nucleophilic displacement reaction of 3,5-dinitrobenzotrifluoride and 4,4′-biphenol. The monomer was reacted with various aromatic dianhydrides via the high temperature polycondensation procedure to provide a series of polyimides. The polyimides, PI-1 to PI-4, show good solubility not only in aprotic solvents, such as N-methyl-2-pyrrolidinone and N,N-dimethylacetamide, but also in many common solvents, such as m-cresol, chloroform and cyclopentanone. PI-4, derived from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride and TFBPDA, was even soluble in toluene. Moreover, PI films exhibit good thermal stability, outstanding transparency in the visible light region and acceptable mechanical and electrical properties. The excellent combined properties of the polyimides make them as a good candidate for fabricating microelectronics.     

Synthesis and properties of novel polyimide fibers containing phosphorus groups in the side chain (DATPPO)

A series of polyamic acid copolymers(co-PAAs) containing phosphorous groups in the side chains were synthesized from [2,5-bis(4-aminophenoxy) phenyl] diphenylphosphine oxide(DATPPO) and 4,4′-oxydianiline(ODA) with 3,3′,4,4′-biphenyltetracarboxylic dianhydride(s-BPDA) through the polycondensation in N,N′-dimethyacetamide(DMAc). The co-PAA solutions were spun into fibers by a dry-jet wet spinning process followed by thermal imidization to obtain co-polyimide(co-PI) fibers. FTIR spectra and elemental analysis confirmed the chemical structure of PI fibers. SEM results indicated that the resulting PI fibers had a smooth and dense surface, a uniform and circle-shape diameter. The thermogravimetric measurements showed that with the increase of DATPPO content, the resulting PI fibers possessed high decomposition temperature and residual char yield, indicating that the PI fibers had good thermal stability. The corresponding limiting oxygen index(LOI) values from the experiment results showed that the co-PI fibers possessed good flame-retardant property. Furthermore, the mechanical properties of the co-PI fibers were investigated systematically. When the DATPPO content increased, the tensile strength and initial modulus of the co-PI fibers decreased. However, the mechanical properties were improved by increasing the draw ratio of the fibers. When the draw ratio was up to 2.5, the tensile strength and initial modulus of the co-PI fibers reached up to 0.64 and 10.02 GPa, respectively. The WAXD results showed that the order degree of amorphous matter increased with increased stretching. In addition, the SAXS results displayed that valuably drawing the fibers could eliminate the voids inside and lead to better mechanical property. WAXD revealed that the orientation of the amorphous polymer influenced the mechanical properties of the fibers.     

Hyperbranched epoxy resins prepared by proton transfer polymerization from an A<Subscript>2</Subscript> + B<Subscript>3</Subscript> system

Epoxy-terminated hyperbranched polymers(EHBPs)were prepared by proton transfer polymerization and characterized by FT-IR,~1H-NMR and GPC.The solution and thermal properties of the uncured samples and mechanical properties of cured samples were examined.The thermo-stable products had good solubility in polar solvents,low solution viscosity and T_gs ranging from 15℃to 33℃depending on their molecular weights.The mechanical properties of cured films were studied and compared with those of a bisphenol-A type epoxy resin.The films of EHBPs had good impact resistance and high gloss values without sacrificing hardness and adhesion.     

High thermal stable polyimide resins derived from phenylethynyl-endcapped fluorenyl oligoimides with low melt viscosities

To improve the processability and thermal stability of polyimide, a series of novel phenylethynyl-endcapped oligoimides(PEPA-oligoimides) with calculated molecular weights(M_nC) were successfully prepared from thermal imidization of 4,4'-(9-fluorenylidene) dianiline(BAFL) as fluorenyl diamine, 4,4′-oxy-diphthalic anhydride(ODPA) as aromatic dianhydride and 4-phenylethynylphthalic anhydride(4-PEPA) acted as reactive end-capping reagent at elevated temperatures. Experiment results indicated that the oligoimides were the mixtures of PEPA-endcapped oligomers with different degrees of polymerization characterized by MALDI-TOF mass spectra. The influence of chemical structures on the melt processabilities of the oligoimides, the thermal, dielectric and mechanical properties of the thermoset resins was studied. The typical oligoimide resin owned minimum melt viscosity of 0.2 Pa·s at around 310 °C and wide melting processing window, suitable for resin transfer molding(RTM). Besides, its corresponding thermal-cured polyimide resin possessed glass transition temperature(T_g) as high as 514 °C. The dielectric constants of polyimide resins decreased from 3.15 to 2.80 by reducing the M_nC. The mechanical properties of the polyimide neat resins were improved gradually with increasing MnC. Finally, the carbon fiber/polyimide(C_f/PI) composite laminates showed excellent mechanical strength retention rate at 350 °C, might be long-term served at extremely high temperature in aerospace and aviation field.     

Magnetic and Heat Resistant Poly(imide-ether) Nanocomposites Derived from Methyl Rich 9H-xanthene: Synthesis and Characterization

In this study a new series of magnetic and heat resistant nanocomposites were prepared based on a highly soluble poly(imideether)(PIE) reinforced with two different types of magnetic nanoparticles via a solution intercalation technique. New PIE with good solubility and desired molar mass containing bulky xanthene rings and amide groups in the side chains was synthesized via thermal cyclization of the poly(amic acid) precursor, obtained from the reaction of a new diamine derived from 9 H-xanthene and 4,4′-oxydiphthalic dianhydride(ODPA). Improved solubility was attributed to the presence of xanthene group and flexible ether linkage in the polyimide backbones that reduce the chain-chain interaction and enhance solubility by penetrating solvent molecules into the polyimide chains. Fe3 O4 nanoparticles(MNPs) which synthesized from chemical co-precipitation route were coated with silica(Si O2), sequentially with(3-aminopropyl)triethoxysilane and poly-melamine-terephthaldehyde(MNPs-PMT), and then separately dispersed in the poly(amic acid) solutions and thermally imidized to form PIE/Fe3 O4 and PIE/MNPs-PMT nanocomposites. The nanostructures and properties of the resultant materials were investigated using FTIR spectroscopy, X-ray diffraction(XRD), field emission scanning electron microscopy(FE-SEM), transmission electron microscopy(TEM), vibrating sample magnetometer(VSM), thermal gravimetric analysis(TGA) and differential scanning calorimetry(DSC). The properties of the nanocomposites were strongly related to the dispersion and interaction between the nanoparticles and PIE matrix. The thermogravimetric analysis(TGA) results showed that the addition of MNPs-PMT nanoparticles resulted in a substantial increase in the thermal stability of the corresponding PIEN. The temperature at 10% weight loss(T10) was increased from 416 °C to 428 °C for PIEN containing 3 wt% MNPs-PMT as compared to neat PIE, as well the char yield enhanced. Furthermore, the MNPs-PMT nanoparticles had better dispersion in the polymer matrix due to the strong intermolecular hydrogen bond interactions between the NH and C=N groups of surface-modified nanoparticles and the PIE matrix than the uncoated Fe3 O4 nanoparticles, and exhibited a better intercalated morphology and improved thermal properties. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature.     

SYNTHESIS AND CHARACTERIZATION OF HIGHLY ORGANO-SOLUBLE POLYIMIDES BASED ON ALICYCLIC 1,8-DIMETHYL-BICYCLO[2.2.2]OCT-7- ENE-2,3,5,6-TETRACARBOXYLIC DIANHYDRIDE AND AROMATIC DIAMINES

Organo-soluble alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, 1,8-dimethylbicyclo[2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (DMEA) and several multialkyl-substituted 4,4′-diaminodiphenylmethane compounds, including 3,3′-dimethyl-4,4′-diaminodiphenyl methane (DMDA), 3,3′,5,5′-tetramethyl-4,4′-diaminodiphenyl methane (TMDA) and 3,3′,5,5′-tetraethyl-4,4′-diaminodiphenylmethane (TEDA). For comparison, the aromatic polyimides (ARPIs) were synthesized from the aromatic dianhydride, 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and the same diamines. The ALPIs exhibited better solubility and transparency,but worse thermal stabilities and mechanical properties than those of the ARPIs. And the ALPIs could be dissolved in common organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), chloroform, tetrahydrofuran, m-cresol and so on. The ALPI films had an UV-Vis cut-off at 320 nm and a transmittance of higher than 80% in the visible region. In addition, the ALPIs showed thermal decomposition temperatures (Td) of about 450℃, which was nearly 100℃ lower than that of the ARPIs.     

Synthesis and Characterization of Poly(ether imide)s Containing m-Methyl and Phthalazinone Moieties

Aromatic polyimides are distinguished for their excellent mechanical and thermal properties in many engineering fields1. However, aromatic polyimides are normally insoluble in common organic solvents, which restricts their applications in some fields. Many efforts have been taken to improve their solubility. Introducing bulky side groups and non-coplanar structure into polymers bone chains is a good way to obtain the polymers with excellent mechanical and thermal properties2. In this paper…     

PREPARATION AND PROPERTIES OF EPOXY RESIN MODIFIED BY LIQUID CHLOROPRENE-HYDROXYETHYLMETHACRYLATE COPOLYMER

The epoxy resin modified by liquid chloroprene-hydroxyethylmethacrylate copolymer (CP-HEMA) is a new kind of structural adhesives with good mechanical properties. By changing its mole-cular structure, it may also have such desirable properties as retardation of combustion, enduringweather aging, inert oils and chemicals. A series of the thermosets of the epoxy resin modifiedby CP-HEMA used as a toughener were prepared. The effects of CP-HEMA content, catalyst con-tent and curing temperature on the mechanical properties of modified epoxy resin system were studied.The thermal weight-loss curves were examined. The two-phase morphology was observed and dis-cussed.     

用于树脂传递模塑成型的苯乙炔封端的酰亚胺预聚体制备

采用4-苯乙炔苯酐(4-PEPA)、1,3-二(3-氨基苯氧基-4′-苯酰基)苯(BABB)和4,4′-双(3-氨基苯氧基)二苯甲酮(APBP)合成了两种苯乙炔苯酐封端的聚酰亚胺预聚体PI-1和PI-2, 并对预聚体的熔体黏度、稳定性、固化后树脂的热稳定性能和机械性能等进行了研究. 结果表明, 制备的预聚体具有较高产率(>95%); 与其它PEPA封端的聚酰亚胺相比, 两种预聚物在较低温度(200 ℃)时均具有很低的熔体黏度(1 Pa·s)和良好的熔体黏度稳定性, 固化后玻璃化温度达到300 ℃以上, 可适用于树脂传递模塑(RTM)成型制备耐高温高性能树脂基复合材料, 且在成型工艺上有了很大改善; 固化后的树脂具有优异的热稳定性能和良好的机械性能.     

Synthesis and characterization of phenylethynyl-terminated polyimide oligomers derived from 2,3,3′,4′-diphenyl ether tetracarboxylic acid dianhydride and 3,4′-oxydianiline

With the goal of improving processability of imide oligomers and achieving high toughness of thermosetting polyimides, a series of 4-phenylethynylphthalic anhydride(PEPA)-terminated imide oligomers prepared by the reaction of 2,3,3',4'-diphenyl ether tetracarboxylic acid dianhydride(a-ODPA) and 3,4'-oxydianiline(3,4'-ODA) with different molecular weights(degree of polymerization: n = 1?9) were formed. The resultant oligomers with different molecular weights were characterized for their chemical architecture, cure behavior, thermal properties, solubility in organic solvents and rheological characteristics. Besides, the thermal properties and tensile test of cured polyimide films were also evaluated. The imide oligomer(degree of polymerization: n = 1) has some somewhat crystalline phase, and imide oligomers(degree of polymerization: n = 2?9) showed excellent solubility(40 wt%) in N-methyl-2-pyrrolidone(NMP) and N,Ndimethylacetamide(DMAc) at room temperature. Furthermore, the rheological properties of imide oligomers showed very low melt viscosity and wider processing window. The cured films exhibited good thermal properties with the glass transition temperatures of 282?373 ?C and 5 wt% thermal decomposition temperatures higher than 551 ?C in nitrogen atmosphere. The elongation at break of the prepared films was found to be high(almost 9.3%).     

耐高温可溶性聚酰亚胺树脂及其复合材料

制备了2种耐高温可溶型聚酰亚胺树脂(PI-1, PI-2)及其复合材料, 系统研究了树脂的工艺性, 纯树脂固化物的热性能及其复合材料的界面形貌、 介电性能和力学性能. 研究结果表明, 树脂低聚物在极性非质子溶剂中具有良好的溶解性, 且熔体黏度较低, 表明其具有优异的加工性能. 两种树脂固化物在空气中的5%热失重温度均高于550 ℃, PI-1树脂的玻璃化转变温度(T_g)为430 ℃, PI-2树脂的T_g为380 ℃. 石英纤维/PI-1和石英纤维/PI-2复合材料具有较低的介电常数和介电损耗. 碳纤维/PI-1复合材料在420 ℃下的弯曲强度保持率可达62%, 层间剪切强度保持率可达48%, 具有较优异的高温力学性能. 采用普通模压工艺制备了厚度高达45 mm的复合材料制件, 进一步证明这2种树脂具有优异的工艺性.     

苯乙炔封端的BTDA系列酰亚胺预聚体的研究

合成了具有苯侧基的二胺单体1,4-双(4'-氨基苯氧基)-2-(苯基)苯(p-TPEQ), 并与3,3',4,4'-苯酮四羧酸二酐(BTDA)进行缩聚反应, 分别以4-苯乙炔苯酐(PEPA)和4-苯乙炔-1,8-萘二甲酸酐(PENA)作为封端剂, 合成了两个系列的苯乙炔封端的酰亚胺预聚体. DSC测试结果表明, 此类预聚体具有比PETI-5更宽的加工窗口; 利用所合成的预聚体制成了具有较高热分解温度热固性交联PI薄膜. 结果表明, PI预聚体加工性能良好, 其交联后具有优异的力学和热学性能; 同时PEPA封端的预聚体树脂具有比PENA封端的树脂更为优异的综合性能.     

含芳基均三嗪环耐高温低聚酰亚胺的合成与性能

通过调控聚合单体的摩尔配比,合成了一系列新型的不同分子链长度的邻苯二甲腈封端含二氮杂萘酮联苯结构低聚酰亚胺,通过FTIR、1H-NMR、WAXD和元素分析对其结构进行表征.以4,4′-二氨基二苯砜为催化剂,低聚物经常压下固化交联后,得到含芳基均三嗪环结构的热固性聚酰亚胺.低聚物表现了良好的溶解性能,可溶于N-甲基-2-...     

新型磺化聚苯并咪唑的合成及性能

以对苯二酚及对氟苯甲腈为原料, 合成了1,4-二(4-羧基苯氧基)苯, 再经磺化反应合成了1,4-二(4-羧基苯氧基)苯-2-磺酸钠(BCPOBS-Na), 并以4,4'-二羧基二苯醚(DCDPE)作为非磺化二酸单体与3,3'-二氨基联苯胺反应合成了一系列磺化聚苯并咪唑(SPBI). 通过红外光谱、 核磁共振及热重分析等手段对聚合物的结构及性能进行了分析. 研究了聚合物的特性黏度、 溶解性、 成膜性及聚合物薄膜的力学性能.     

4-苯乙炔基苯胺封端聚酰亚胺树脂的合成与性能研究

使用4-苯乙炔基苯胺(4-PEA)作为反应性封端剂,和3,3′,4,4′-二苯醚四酸二酐(ODPA),3,3′,4,4′-联苯四酸二酐(BPDA),1,4-双(4′-氨基-2′-三氟甲基苯氧基)苯(BTPB)和3,4′-二氨基二苯醚(3,4-′ODA)反应合成了系列4-苯乙炔基苯基封端的聚酰亚胺低聚物,对低聚物的化学结构、热性能和熔体粘度以及固化后树脂的热性能等进行了研究.实验结果表明,低聚物均具有一定的结晶性,含有ODPA的聚酰亚胺低聚物较之含有BPDA的低聚物具有更低的熔体粘度,且出现最低熔体粘度的温度更低;固化后的树脂表现出良好的热性能,含有BPDA的树脂具有更高的玻璃化转变温度;系列低聚物中二胺单体的比例对于低聚物的熔体粘度和固化后树脂的热稳定性有一定影响.     

Synthesis and Properties of Novel Thermal Stable Thermoplastic Poly(ester-imide-ether) Elastomers Based on N,N′-Bis(2-carboxyethyl)-3,3′,4,4′ Biphenyltetracarboxylimide Unit with Excellent Mechanical Properties

A series of thermoplastic poly(ester-imide-ether) (PEIE) elastomers, with different ratios of soft/hard segment 85/15, 80/20 and 70/30, were prepared from 1, 4-butanediol (BD), poly(tetramethylene glycol) (PTMG) and imide dicarboxylic acid monomer based on 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and glycine (GLY). The chemical structures of the imide dicarboxylic acid and PEIEs were characterized by FT-IR and ¹H-NMR, respectively. The intrinsic viscosities, thermal properties and mechanical properties of these PEIEs were investigated. The results show that introduction of imide group endows the PEIEs with excellent thermal stability, the melting point of PEIEs at about 220°C, and the temperature of 5% weight loss appears at the range of 332–358°C. In addition, the mechanical properties of PEIEs are also improved with the increment of imide units, the maximum stress and strain reached to 17.15 MP and 1043.75%, respectively.     

Synthesis of high thermal stability polybenzoxazoles via ortho‐imide‐functional benzoxazine monomers

We report our work for preparing cross‐linked polyimide via a series of imide functional benzoxazine resins as precursors. The structures of synthesized monomers have been confirmed by ¹H NMR and FT‐IR. Among this class of benzoxazine monomers, the ortho‐imide functional benzoxazine resins show useful features both in the synthesis of benzoxazine monomers and the properties of the corresponding thermosets. For the cross‐linked polyimides based on ortho‐imide functional benzoxazine, an additional route is adopted to form a more thermally stable cross‐linked polybenzoxazole with the release of carbon dioxide. The ortho‐imide functional benzoxazine resins show the possibility to form high performance and even super high performance thermosets with low cost and easy processability. The thermal properties are evaluated by DSC and TGA. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1330–1338     

可溶性共聚型聚苯并咪唑的合成及性能

以对苯二酚和对氟苯甲腈为原料, 合成了1,4-二(4-羧基苯氧基)苯, 并与4,4′-二羧基二苯醚作为共聚单体与3,3′-二氨基联苯胺反应合成了共聚型聚苯并咪唑, 通过红外光谱、核磁共振和热重分析等手段对聚合物的结构及热性能进行了分析. 研究了聚合物的黏度、溶解性、成膜性及聚合物薄膜的力学性能.