侧链含硫的联苯四酸二酐及其聚酰亚胺的合成

以3,3′,4,4′-联苯四酸二酐(BPDA)为原料合成了2,2′-苯硫醚-4,4′,5,5′-联苯四酸二酐,然后分别与对苯二胺和4,4′-二胺基二苯醚通过高温缩聚法制备出两种侧链含硫的新型聚酰亚胺(PI)(PI-1和PI-2).与文献报道的直接由BPDA为二酐制备的PI相比,PI-1和PI-2均表现出良好的有机可溶性...     

基于异构联苯二酐的热塑性聚酰亚胺性能研究

制备了一系列基于异构联苯二酐[2,2’,3,3’-联苯四甲酸二酐(3,3’-BPDA)、2,3’,3,4’-联苯四甲酸二酐(3,4’-BPDA)和3,3’,4,4’-联苯四甲酸二酐(4,4’-BPDA)]的聚酰亚胺(PI)均聚物和共聚物,比较研究了这些聚合物的热学和力学性能。结果表明,当二胺结构相同时,基于3,3’-BPDA和3,4’-BPDA的PI均聚物或共聚物较基于4,4’-BPDA的均聚物有更高的玻璃化转变温度(Tg)和更好的热加工性;当二酐结构相同时,基于对苯二胺(PDA)的PI的Tg高于基于4,4’-二氨基二苯醚(ODA)的PI。基于3,4’-BPDA/PDA的PI具有最高的Tg,其值为382℃,由其制备的薄膜的拉伸强度为100 MPa,拉伸弹性模量为1.8 GPa,断裂伸长率为12%。基于4,4’-BPDA/PDA的PI薄膜具有最高的拉伸性能,其拉伸强度为307 MPa,拉伸弹性模量为4.1 GPa,断裂伸长率为23%。基于3,4’-BPDA/ODA和3,3’-BPDA/4,4’-BPDA(1/1)/ODA的PI模塑料均具有高于300℃的Tg和较好的力学性能,其冲击强度分别达到82.3 kJ/m2和94 kJ/m2。     

对苯二胺/间苯二胺/3,3',4,4'-联苯四甲酸二酐三元缩聚及其性能研究

以对苯二胺、间苯二胺和3,3',4,4'-联苯四甲酸二酐为单体,在低温条件下,通过缩合聚合得到高分子量的预聚体聚酰亚胺酸粘稠溶液,涂膜、热亚胺化后制得聚酰亚胺薄膜。通过FTIR、TGA及UV-Vis等对其结构和性能进行了表征。结果表明,聚酰亚胺薄膜具有优异的透明性、疏水性和力学性能,且对苯二胺型聚酰亚胺薄膜的力学性能高于间苯二胺型聚酰亚胺薄膜的力学性能。     

对苯二胺/间苯二胺/3,3',4,4'-联苯四甲酸二酐三元缩聚及其性能研究

以对苯二胺、间苯二胺和3,3',4,4'-联苯四甲酸二酐为单体,在低温条件下,通过缩合聚合得到高分子量的预聚体聚酰亚胺酸粘稠溶液,涂膜、热亚胺化后制得聚酰亚胺薄膜。通过FTIR、TGA及UV-Vis等对其结构和性能进行了表征。结果表明,聚酰亚胺薄膜具有优异的透明性、疏水性和力学性能,且对苯二胺型聚酰亚胺薄膜的力学性能高于间苯二胺型聚酰亚胺薄膜的力学性能。     

3,3′,4,4′-联苯四甲酸二酐的合成工艺

3,3′,4,4′-联苯四甲酸二酐是合成全芳香族聚酰亚胺的重要单体.对其合成路线进行了优化：以邻苯二甲酸酐为原料，经溴化、催化脱卤偶联、脱水环化得到高纯度的3,3′,4,4′-联苯四甲酸二酐.同时通过对Pd/C的循环利用进行了研究，确定了Pd/C的合理使用方案.各步反应的最佳条件（反应试剂、反应温度、反应时间、摩尔收率）分别为，溴化：水，75 ℃，4 h，78％; 脱卤偶联：水，100 ℃， 2 h，90.4％;脱水环化：乙酸酐，回流， 2 h，97％.优化后路线操作简单，各步反应副反应少，收率较高，总收率达68.4％，产品纯度高，金属离子含量符合要求.     

3,3′,4,4′-联苯四甲酸二酐的合成工艺

3,3′,4,4′联苯四甲酸二酐是合成全芳香族聚酰亚胺的重要单体.对其合成路线进行了优化:以邻苯二甲酸酐为原料,经溴化、催化脱卤偶联、脱水环化得到高纯度的3,3′,4,4′联苯四甲酸二酐.同时通过对Pd/C的循环利用进行了研究,确定了Pd/C的合理使用方案.各步反应的最佳条件(反应试剂、反应温度、反应时间、摩尔收率)分别为,溴化:水,75℃,4h,78%;脱卤偶联:水,100℃,2h,90.4%;脱水环化:乙酸酐,回流,2h,97%.优化后路线操作简单,各步反应副反应少,收率较高,总收率达68.4%,产品纯度高,金属离子含量符合要求.     

开孔聚酰亚胺泡沫粘接性能研究

探讨了BHPI-J-2010胶粘剂的固化度、耐热性、固化工艺、粘接铝的拉剪强度及粘接聚酰亚胺泡沫的可行性;研究了BHPI—J-2010胶粘剂粘接聚酰亚胺泡沫／45号钢的拉伸性能及固化工艺;考查了开孔聚酰亚胺泡沫／45号钢粘接试样高温拉伸和蠕变性能及胶粘剂的使用寿命。结果表明,BHPI—J-2010胶粘剂对开孔聚酰亚胺泡沫具有良好的粘接性能。     

耐高温聚酰亚胺类胶粘剂制备及性能分析

为了分析影响耐高温聚酰亚胺类胶粘剂性能的因素,使用C₁₂H₁₂N₂O和C₂₇H₂₆N₂O₂作为二胺单体,C₁₇H₆O₇作为二酐单体,通过封端剂C₄H₂O₃和反应溶剂C₅H₉NO的共同作用制备了一种聚酰亚胺胶粘剂,测试了不同因素对胶粘剂粘接性能的影响。结果表明,固体质量分数、粘结件表面粗糙度、C₁₂H₁₂N₂O和C₂₇H₂₆N₂O₂单体的摩尔比、二酐与二胺单体的摩尔比、聚酰胺酸固化工艺、亚胺化程度和亚胺化方式都会对耐高温聚酰亚胺类胶粘剂的性能产生影响。当胶粘剂固体质量分数为30%、表面粗糙度的打磨砂纸型号为600...     

3,3′,4,4′—二苯醚四甲酸二酐的合成方法

本文全面综述了３,３′,４,４′－二苯醚四甲酸二酐的合成方法并加以评述。给出了１９篇参考文献。     

基于二酐分子设计聚酰亚胺的研究进展

聚酰亚胺作为一类高性能聚合物,具有突出的物理、化学性能,较高的成本和难以加工是目前聚酰亚胺存在的主要问题,并限制了聚酰亚胺材料更好的发展。目前国内外学者对聚酰亚胺各方面的评述工作不胜枚举,而从聚合物合成单体-二酐出发的评述工作尚属首次。文章主要介绍了新颖二酐单体的设计合成及研究进展。     

Synthesis,structure and properties of polyimide–silica hybrid composites based on biphenyltetracarboxylic dianhydride

A simple and efficient way of synthesizing nanocomposite films using a dispersion technique is reported, with the resulting films having improved mechanical and thermal properties. Nano‐SiO₂ was used in a biphenyltetracarboxylic dianhydride‐based poly(amic acid) precursor and found to be dispersed up to 7 wt% without any additives. The composites were cast to make 10 µm solid films to establish structure and property relationships between liquid and solid film. The structures of the liquid composite materials were studied using NMR and Fourier transform infrared spectroscopy. Solid film properties such as tensile strength, contact angles and thermal behaviour were evaluated for comparison. The properties of the composite films were found to be enhanced compared to polyimide film itself. Atomic force microscopy and macroscale mechanical measurements showed that composite films with more dipolar bonding interactions have higher elastic moduli and are more deformable. They yield higher adhesion energies, and therefore composite coatings offer greater adhesion. There was a limitation in the film formation beyond 5 wt% of silica. Copyright © 2011 Society of Chemical Industry     

Polyimides from isomeric biphenyltetracarboxylic dianhydrides and the effects of chemical structure on solubility

A series of homopolyimides and copolyimides was synthesized by the solution condensation of biphenyltetracarboxylic dianhydride (BPDA) isomers and various diamines followed by chemical imidization. These polyimides had intermediate to high molecular weights with inherent viscosities of 0.34–1.01 dL/g for homopolyimides and 0.48–1.02 dL/g for copolyimides. Thermogravimetric analysis indicated that the aromatic polyimides were stable up to 500°C, and the 5% weight loss temperatures were recorded in the range of 506–597°C in an air atmosphere and in the range of 517–601°C in a nitrogen atmosphere, depending on the diamines used. The glass transition temperatures of aromatic homopolyimides were above 271°C, while the glass transition temperatures of the copolyimides increased with an increase in the 2, 2′, 3, 3′‐BPDA‐component. The effects of the chemical structure of the polymer chain on the solubility were investigated. It was found that the solubility of BPDA‐based polyimides could be improved by the introduction of flexible units, nonlinear and non‐coplanar units, and copolymerization. The polyimides with nonlinear and non‐coplanar units derived from 2, 2′, 3, 3′‐BPDA appeared to have prominently enhanced solubility in polar aprotic solvents and polychlorocarbons when compared with the homopolyimide derived from 3, 3′, 4, 4′‐BPDA.     

Preparation and properties of rigid polyimide foams derived from dianhydride and isocyanate

A series of rigid polyimide (PI) foams were synthesized via the reaction of a first solution with a second solution. The first solution was isocyanate‐terminated polyimide prepolymers; the second solution contained deionized water and surfactant. The effect of different water contents and isocyanate index on the structures and properties of rigid PI foams were investigated. The apparent density, hardness, compressive strength, and the 5% weight loss temperatures (T_5%) decreased with the increase of water content. With the increase of isocyanate index, the apparent density and the T_5% values decreased, whereas the glass transition temperatures (T_g) increased and the hardness, compressive strength first increased and then decreased. The rigid PI foams composed of closed‐cells were confirmed by scanning electron microscopy. The maximum compressive strength of rigid PI foams prepared was up to 1.31 MPa. Moreover, excellent thermal stability was presented with the T_5% values were all above 360°C and the residual weights of the foams (R_w) were more than 50% at 800°C. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Thermal imidization behavior of aromatic poly(amic dialkyl ester) precursors derived from biphenyltetracarboxylic dianhydride

Summary Poly(amic dialkyl ester) precursors of high performance poly(4,4-oxydiphenylene biphenyltetracarboximide) (BPDA-ODA) and poly(p-phenylene biphenyltetracarboximide) (BPDA-PDA) were synthesized and their thermal imidizations were investigated isothermally and nonisothermally by thermogravimetry. All precursors showed a two-step imidization behavior, fast imidization at early stage and slow imidization at intermediate and later stage. Kinetic parameters were estimated from the conversion versus time plots with the first-order rate equation. The imidization behaviors observed were interpreted with considering the T_g variation, the natures of alkyl leaving group and precursor backbone, and the flexibility of polymer chain. In addition, the onset temperature of imidization and T_g of precursors were estimated from the imidization kinetic data.     

Influence of diamine rigidity and dianhydride rigidity on the microstructure,thermal and mechanical properties of cross-linked polyimide aerogels

Journal of Porous Materials - Polyimide aerogels (PAs) using different monomers were prepared by cross-linking with a low-cost aminosilane, bis(trimethoxysilylpropyl) amine. The influence of...     

Morphology of polyimide fibers derived from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride and 4,4′‐oxydianiline

As one member of high performance fibers, aromatic polyimide fibers possess many advantages, such as high strength, high modulus, high and low temperature resistance, and radiation resistance. However, the preparation of the high performance fibers is so difficult that the commercial fibers have not been produced except P84 with good flame retardancy. In this report, a polyimide was synthesized from 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA) and 4,4′‐oxydianiline (ODA) and the fibers were prepared from its solution by a dry‐jet wet‐spinning process. The formation of the as‐spun fibers in different coagulation bath composition was discussed. Scanning electron microscope (SEM) was employed to study the morphology of the as‐spun fibers. As a result, the remnant solvent existed in the as‐spun fibers generated from coagulation bath of alcohol and water. There were many fibrils and microvoids with the dimension of tens of nanometers in the fibers. One could observe the obvious fibrillation and the drawn fibers. The measurement for the mechanical properties of the fibers with a drawing ratio of 5.5 indicated that tensile strength and initial modulus were 2.4 and 114 GPa, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 669–675, 2004     

Effect of in situ-formed polydimethylsiloxane on the properties of polyimide hybrids

Polyimide-polydimethylsiloxane (PI-PDMS) hybrids were synthesized by combining an in situ sol–gel reaction of diethoxydimethylsilane (DEDMS) and imidization of poly(amide acid) (PAA) prepared from pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (ODA). Transparent hybrid films were obtained with up to 3 wt.% PDMS content corresponding to the relatively small domain size of PDMS as confirmed by scanning electron microscopy. The hybrid films with up to 3 wt.% of PDMS content showed higher tensile modulus, strength and elongation at break than those of pristine PI, due to the in situ-formed PDMS. The thermal stability of the hybrids also increased with the increase of PDMS content, as evidenced by TGA.     

Organosoluble and light-colored fluorinated semialicyclic polyimide derived from 1,2,3,4-cyclobutanetetracarboxylic dianhydride

In this study, the alicyclic dianhydrides 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA) was polymerized with seven kinds of fluorinated aromatic diamines, 2,2′-bis(trifluoromethyl)-4,4′-diaminobiphenyl (1), 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (2), 1,4-bis(4-amino-2-trifluoromethylphenoxy)diphenyl (3), 1,4-bis(4-amino-2-trifluoromethylphenoxy) diphenyl ether (4), 2,2-bis[4-(4-amino-2-trifluoromethylphenoxy)phenyl]hexafluoropropane (5), 4,4′-bis(4-amino-2-trifluoromethylphenoxy)diphenyl sulfone (6), and 2,7-bis(4-amino-2-trifluoromethylphenoxy)naphthalene (7), via a two-step polycondensation procedure to prepare seven kinds of fluorinated semialicyclic polyimides (PI) PI-1 ∼ PI-7. The structures of these polyimides were confirmed by infrared spectroscopy (IR). Solubility of the polyimides was tested in various organic solvents and their thermal properties were investigated by dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). Ultraviolet-visible spectra (UV-vis) and near infrared absorption spectra (NIR) were obtained to evaluate the optical properties of these polyimides. The obtained polyimides PI-1 ∼ PI-7 displayed excellent solubility in a variety of organic solvents; they were readily soluble in amide-type polar solvent. These polyimide films exhibited good optical transparency in the visible light region (400–700 nm) with the transmittance higher than 80% at 450 nm, and these polyimide films showed little absorption at the optocommunication wavelengths of 1.30 and 1.55 μm. These polyimides showed good thermal stability with the 10% thermal decomposing temperatures higher than 443°C in nitrogen and the glass transition temperatures higher than 265°C. In addition, the effect of the structure of fluorinated diamines on the properties of polyimide films was also compared. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

高温热处理对聚酰亚胺薄膜性能的影响

研究了高温热处理对聚酰亚胺(PI)薄膜拉伸性能和热性能的影响。在薄膜完全环化后,随着热处理温度的升高,薄膜的拉伸强度、弹性模量先增大后基本保持不变,断裂伸长率先保持不变后明显降低,热膨胀系数也显著降低,而薄膜的玻璃化转变温度略有增大。高温热处理工艺可制备高强度和低热膨胀系数的高性能PI薄膜。     

Effect of molecular orientation on the dielectric properties of spin-coated polyimide films

The effect of molecular orientation on the dielectric properties of spin-coated polymide films has been studied in Situ for pyromellitic dianhydride with 4,4′-oxydianiline (PMDA/ODA) and biphenyldianhydride with p-phenylendiamine (BPDA/PPD). The degree of molecular orientation is characterized by the optical anisotropy between the in-plane and the through-plane, refractive indices. The through-plane dielectric properties are measured by fabricating parallel-plate capacitors directly onto the silicon substrate. Both the birefringence and the dielectric constant of PMDA/ODA polyimide vary with film thickness; however, these properties are independent of film thickness for BPDA/PPD films. To confirm that the measured dielectric constant obtained from the parallel-plate structures is free from a significant edge effect, finite element modeling of the electrstatic potential within the dielectric edge effect, finite element modeling of the electrostatic potential within the dielectric is performed. Models for both isotropic and anisotropic dielectric properties indicated that the fringing effects are indeed negligible for the film thicknesses examined. Thus, the changes observed in the measured dielectric constant are attributed to the variations in the molecular orientation. The optical anisotropy observed for the polyimides suggests a corresponding dielectric anisotropy in the films. An estimation using the Maxwell relation indicates that the dielectric anisotropy at 10⁵ Hz is 0.31 for PMDA/ODA and 0.85 for BPDA/PPD. © John Wiley & Sons, Inc.