分子结构对6FDA型聚酰亚胺透气性能的影响

理想的气体分离膜材料应该同时具有高的透气性和良好的透气选择性、高强度、耐高温、耐化学介质和良好的成膜加工性能,聚酰亚胺是一类具有各种优良性能的气体分离膜材料,其中尤以6FDA型聚酰亚胺最引人注目,这类聚酰亚胺在保持普通聚酰亚胺高性能的基础上,改善了加工性能,它们可溶于极性非质子溶剂,可采用相转换法制成不对称膜。本文报道这类聚酰亚胺的分子结构与气体分离性能的关系。     

聚酰亚胺碳分子筛气体分离膜的研究进展

聚酰亚胺碳分子筛膜由于具有较高的热稳定性、耐化学性、气体渗透性和选择性,而受到广泛关注。根据近年来聚酰亚胺碳分子筛膜在气体分离方面的研究现状,详细介绍了填充改性、对前驱体进行预处理和聚酰亚胺单体改性的研究成果,并展望了聚酰亚胺碳分子筛分离膜的发展趋势,以期为未来高效分离膜的研发提供参考。     

含叔丁基聚酰亚胺均质膜的气体分离性能

采用高温“一步法”缩聚合成了一系列含叔丁基的可溶性芳香聚酰亚胺树脂, 然后通过溶液浇注法制得相应均质薄膜, 并对其气体分离性能进行了测试, 同时研究了二酐结构和温度对聚酰亚胺均质膜气体分离性能的影响. 结果表明, 对于H₂, N₂, O₂, CO₂和CH₄ 等5种气体, 含叔丁基聚酰亚胺均质膜不仅表现出良好的透气性, 而且具有较高的气体透过选择性, 4,4'-(六氟异丙烯)二酞酸酐(6FDA)和均苯四甲酸二酐(PMDA)两类聚酰亚胺均质膜的气体分离性能最佳. 除CO₂外, 这两类聚酰亚胺均质膜的气体渗透系数随温度升高而升高, 而所有测试气体在这两种均质膜中的扩散系数和溶解度系数均随温度升高而增大.     

DDBT类可溶性聚酰亚胺的合成与性能研究

由二甲基-5,5'-3,7-二苯并噻吩二胺（DDBT）和3,3',4,4'-二苯砚四羧酸二酐（DSDA）、2,2'-双（3,4-二羧酸）六氟丙烷二酐（……FDA）、均苯四羧酸二酐（PMDA）、联苯四羧酸二酐（BPDA）等多种二酐单体进行缩聚反应制备了新型可溶性聚酰亚胺。测定了其特性粘度为0.6-0.9dL/g;DDBT与DSDA、6FDA反应得到的聚酰亚胺在非质子强极性溶剂中具有良好的溶解性。用IR、热力学分析等手段对DDBT类聚酰亚胺进行了表征,并对可溶性DDBT-DSDA聚酰亚胺膜作了进一步的研究,推导出了苯在DDBT-DSDA聚酰亚胺膜中动态吸附初期的吸附方程。实验结果表明DDBT-DSDA聚酰亚胺膜对苯具有特殊的亲和力。     

聚酰亚胺气体分离膜的进展

本文叙述了近年来聚酰亚胺气体分离膜的发展概况。讨论了聚合物结构、共聚改性、交联改性和成膜历史对聚酰亚胺透气性能的影响。脂环族聚酰亚胺和六氟二酐(6FDA)型聚酰亚胺兼具有高透气性和高透气选择性,是一类具有发展前途的气体分离膜材料。     

过渡金属有机络合物添加剂对聚酰亚胺气体分离膜性能的影响

采用具有庞大取代基团的过渡金属有机络合物作为添加剂制备了聚酰亚胺气体分离膜,研究了过渡金属盐、有机配体和金属络合物对聚酰亚胺均质膜和非对称膜氢、氮气体透过性能的影响,结果表明过渡金属盐添加剂提高了分离系数,但降低了气体透过速率;有机配体添加剂增大了气体透过速率却降低了分离系数;以络合物作添加剂时,可在不降低分离系数的情况下使气体透过速率得到提高,是一种改进气体分离膜性能的有效方法。     

抗溶胀型聚酰亚胺气体分离膜的制备及其研究进展

膜分离技术具有绿色、高效、低能耗等特点.聚酰亚胺膜具有优异的气体分离性能及机械性能,但在分离高压天然气及生物气时,聚酰亚胺膜易被CO2溶胀塑化,导致膜的选择性下降.近年来,已经报道了多种可用于提高聚酰亚胺膜抗溶胀的技术.本文介绍了由于CO2渗透引起的聚合物膜塑化机理,并详述了热退火、热交联、化学交联、热重排、与纳米材料共混及与聚合物共混等用于抑制聚酰亚胺膜塑化的方法,提出了用于天然气及生物气分离的膜材料,未来的主要研究方向是开发同时具备高气体渗透性及高抗CO2塑化的聚酰亚胺膜材料.     

芳香聚酰亚胺气体分离膜

芳香聚酰亚胺一直在电子、复合材料及粘接剂等领域广泛地应用。最近,聚酰亚胺膜已用于气体的分离过程。这是因为芳香聚酰亚胺是具有高玻璃化温度的玻璃态聚合物,它对小分子比大分子有更大的选择透过性,高选择性是与玻璃态聚合物的僵硬主链,对不同尺寸的分子提供筛分作用相连系的。新开发的芳香聚酰亚胺膜是用联苯四甲酸二酐与芳香二胺缩聚制备的聚酰亚胺溶液制造的。这种中空纤维状的膜是由一个多孔结构支撑的一个很薄的外表面组成的。它可通过聚合物溶液采用干——湿法过程纺丝而成,经溶剂交换干燥,外层的致密部分由计算可知厚度低于0.1μm。它对H_2与CO、CH_4.N_2及其它气体的分离有高度的选择性。由于它具有聚酰亚胺特有的耐高温性能,所以可以在很广的气体加工条件下使用。这种膜对水蒸气有很高的透过性,因而也可用于有机蒸气的脱水,或空气干燥。此膜对水蒸气的透过速度为乙醇的100～200倍。30%的乙醇水溶液,经一次膜分离,浓度可提高到99%。空气干燥系统可产出达到-50℃露点的空气。     

温度和压力对六氟二酐型聚酰亚胺的透气性能的影响

本文研究了温度和压力对五种六氟二酐（６ＦＤＡ）型聚酰亚胺膜对Ｈ_２、ＣＯ_２、Ｏ_２、Ｎ_２和ＣＨ_４五种气体透过性能的影响．在３０－１００℃区间，五种聚酰亚胺的透气系数与温度的关系均符合Ａｒｒｈｅｎｉｕｓ关系式；在０．３－１．２ＭＰａ区间，压力对透气系数的影响很小．６ＦＤＡ－４，４＇－二氨基二苯酮（ＤＡＢＰ）和６ＦＤＡ－３，３＇－二甲基二苯甲烷二胺（ＤＭＭＤＡ）在１００℃仍然具有较大的透气选择系数，是比较好的气体分离膜材料．     

含有聚醚链段的可溶性聚酰亚胺气体分离膜材料及其性能

将4,4'-六氟亚异丙基-邻苯二甲酸酐(6FDA)和1,3-苯二胺(mPDA)与二端氨基聚醚缩聚, 得到含有聚醚柔性链段的聚酰亚胺气体分离膜材料. 所合成的共聚聚酰亚胺在N-甲基吡咯烷酮(NMP)和四氢呋喃(THF)等有机溶剂中具有良好的溶解性能. 研究了O2, N2, H2, CH4和CO2在聚酰亚胺均质膜中的渗透性能, 考察了二端氨基聚醚的含量、链长和化学结构对气体渗透性能的影响. 结果表明, 聚醚链段的引入增大了气体的扩散系数, 气体的渗透系数显著增大; 聚醚链段与CO2相对较强的相互作用, 增大了对CO2/N2的溶解选择性, CO2/N2的分离性能优于CO2/CH4, 同时CO2比H2优先透过膜.     

The effect of morphology on sorption and transport of carbon dioxide in a polyimide from 3,3′,4,4′-biphenyltetracarboxylic dianhydride and 4,4′-oxydianiline

Sorption and transport of CO₂ have been investigated for polyimide films prepared from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-oxydianilline (ODA) as well as for a chemically identical commercial polyimide film, Upilex-R. The BPDA-ODA polyimide films annealed above the glass transition temperature (270°C) are found to have some degree of ordering owing to molecular aggregation of polymer chains, whereas the films as-cast are amorphous. The solubility, permeability, and diffusion coefficients decrease significantly with increasing density or increasing average degree of molecular aggregation. The influence of morphology on the parameters in the dual-mode sorption and transport model has also been investigated. With an increase in density, the Langmuir capacity constant and the diffusion coefficients for Henry's law and Langmuir populations decrease by a larger factor than the Henry's law solubility constant. These results can be tentatively interpreted by assuming either a one-phase or two-phase structure for these polyimide films.     

引入三氟甲基侧基对对苯醚型聚酰亚胺薄膜吸水性及水蒸汽透过性的影响

合成了3种含三氟甲基的芳香二胺,进而与3,3′,4,4′-联苯四甲酸二酐(BPDA)缩聚,得到3种对苯醚型含氟聚酰亚胺薄膜,并由4,4′-二氨基二苯醚（4,4′-ODA）与BPDA缩聚得到聚酰亚胺薄膜。 对4种聚酰亚胺薄膜的水蒸汽透过率、吸水性和热学性能的测试结果表明,其中聚合物PI-1（2,2′-BTF-4,4′-BADE+BPDA;BTF：双三氟甲基;BADE：二氨基二苯醚）的水蒸汽透过率为7.70 g/（h·m2）,吸水率为0.67%,玻璃化转变温度为259.74 ℃,质量损失5%的温度为521.40 ℃,具有良好的水蒸汽透过性和低吸水性。     

一种可溶性聚酰亚胺的合成与性能研究

选用三苯二醚四酸二酐 (HQDPA)和二甲基二苯甲烷二胺 (DMMDA)为单体 ,在NMP中通过低温溶液缩聚 化学亚胺化法合成了高分子量可溶性聚醚酰亚胺PI(HQDPA DMMDA) .通过FT IR、WAXD、TG DTG以及DSC等手段对聚酰亚胺的结构和性能进行了表征 .结果表明 ,合成的PI为无规高分子结构 ,平均分子链间距为 0 5 16 3nm ;易溶于N 甲基吡咯烷酮、N ,N 二甲基乙酰胺和四氢呋喃等极性溶剂中 ;其 10 %的分解温度为5 2 8℃ ,玻璃化转变温度Tg 为 2 5 1℃ ;断裂伸长率为 2 4 % ,断裂强度为 10 7MPa ;2 5℃时 ,PI均质膜的透H2 系数为 3 80 9Barrer ,H2 N2 、H2 CH4 的理想分离系数为 16 6 9、2 14 0 ;其透N2 、O2 、CO2 和CH4 系数均在 0 0 18～0 5 76Barrer之间     

The synthesis and characterization of polyimide homopolymers based on 5(6)‐amino‐1‐(4‐aminophenyl)‐1,3,3‐trimethylindane

The isomeric diamine monomer 5(6)‐amino‐1‐(4‐aminophenyl)‐1,3,3‐trimethylindane (DAPI) was successfully synthesized via the dimerization of α‐methylstyrene followed by nitration and reduction. High molecular weight, soluble polyimides were synthesized via ester–acid solution imidization techniques and had glass‐transition temperature values ranging from 247 to 369 °C. The polymers were soluble in common organic solvents because of the asymmetric and nonplanar nature of DAPI and displayed good short‐term thermal stability by thermogravimetric analysis, as shown by their 5% weight‐loss values above 500 °C in air. The DAPI/(3,4‐dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) polyimide also showed 2‐h thermal stability at 400 °C under nitrogen, despite the partial aliphatic character. Refractive index values as low as 1.571 were observed for DAPI/6FDA, which allows an estimated dielectric constant of 2.47 to be derived. The permeation of O₂ and N₂ was conducted on thin dense films. The bulky, bent, and isomeric nature of DAPI imparted film‐forming membranes that permitted high O₂ permeability. In combination with 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride (BTDA), DAPI had a good combination of O₂ permeability and O₂/N₂ selectivity values of 2.8 Ba and 7.3, respectively. The polymerization method utilized to facilitate the cyclization of DAPI/BTDA to the polyimide affected the final thermal properties of the resulting polymer. The chemical imidization of DAPI/BTDA generated a polyimide with a glass‐transition temperature value of 311 °C and a 5% weight‐loss value in air of 457 °C. However, thermal and ester–acid imidization routes yielded an increase in the thermal properties. The ester–acid solution imidization of DAPI/BTDA produced a polymer glass‐transition temperature value of 333 °C and a 5% weight‐loss value of 525 °C in air. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2840–2854, 2000     

Stable second‐order NLO semi‐IPN system based on bipyridine‐containing polyimide and alkoxysilane dye

An organosoluble polyimide based on bipyridyl moiety and an alkoxysilane dye have been developed for second‐order non‐linear optics (NLOs). This bipyridine‐containing polyimide exhibits a glass transition temperature of 254°C and a degradation temperature of 400°C. An NLO‐active semi‐interpenetrating network (IPN) system was prepared by blending the polyimide with the alkoxysilane dye via in situ sol‐gel process of alkoxysilane. The selection of this bipyridine‐containing polyimide as the polymeric matrices provides improved solubility and thermal stability, and most importantly enhanced intermolecular interactions. No aggregation of the NLO chromophores in the polyimide matrices was observed through morphology and NLO studies. Under the limitation of chromophore degradation at elevated temperatures, the pristine poled/cured alkoxysilane dye exhibits poorer long‐term stability. By introducing the polyimide upon a silica network by the semi‐IPN system, randomization of the oriented chromophores can be effectively suppressed. Using in situ contact poling, the r₃₃ coefficients of 2.2–17.0 pm/V were obtained for the optically clear semi‐IPN NLO materials. Excellent temporal stability (100°C) was also achieved for these semi‐IPN materials. Copyright © 2005 John Wiley & Sons, Ltd.     

通过掺杂柔性二胺单体增强聚酰亚胺性能:分子动力学模拟

聚酰亚胺(PI)被视为一类以其卓越性能而闻名的高性能聚合物材料。传统聚酰亚胺的一个关键问题是其熔体的加工性能较差。在本研究中,设计了一种新的聚酰亚胺单体Am-Di,其特点是由氮原子连接的苯环组成的柔性结构。通过详尽的研究,我们对Am-Di掺杂到聚酰亚胺中对其玻璃化转变温度、均方位移、力学性能和相对介电常数等性质的影响进行了深入探讨。结果表明,在聚酰亚胺体系中,掺杂新型二胺可以加速聚酰亚胺分子链的运动,从而降低聚酰亚胺体系的玻璃化转变温度。在Am-Di掺杂量为20%的情况下,PI-20%表现出最高的弹性模量(4.505Gpa),比纯PI高1.2倍。此外,随着掺杂比例的增加,聚酰亚胺的相对介电常数降低。这些发现表明,Am-Di的掺杂对聚酰亚胺材料的性能具有积极影响,特别是在增强机械性能和调控电气性能方面,为进一步改进聚酰亚胺材料的设计和应用提供了有价值的见解。     

含硫醚结构均苯型聚酰亚胺的合成及表征

以4,4′-二氨基二苯硫醚(SDA)和均苯四酸酐(PMDA)为原料,通过溶液缩聚法-热酰亚胺/化学酰亚胺化的方法制备了一种含硫醚结构均苯型聚酰亚胺.利用高级旋转流变仪建立了在线跟踪反应进程的方法,采用热失重分析仪研究反应条件对热酰亚胺化及化学酰亚胺化法的影响,这些方法的建立为进一步制备高性能的聚酰亚胺提供有效的实验手段.采用小角激光光散射法、红外光谱、元素分析、接触角仪、DSC等方法对聚合物的结构与性能进行表征.结果显示,硫醚结构的引入,可有效改善聚合物薄膜的表面性能,其与铜箔之间的粘附功明显大于传统聚酰亚胺,在无胶挠性线路板应用方面显示出较好的应用前景.所获聚合物的Mw为(6.7±1.6)×104,分解温度均高于560℃;DSC的结果显示所制备的两种酰亚胺化聚合物均具有较高的玻璃化转变温度,相比之下,化学酰亚胺化更有利于获得高酰亚胺化程度的聚合物,产物的玻璃化转变温度也更高.     

Polyimides from isomeric diphenylthioether dianhydrides

3,3′,4,4′‐Diphenylthioether dianhydride (4,4′‐TDPA), 2,3,3′,4′‐diphenylthioether dianhydride (3,4′‐TDPA), and 2,2′,3,3′‐diphenylthioether dianhydride (3,3′‐TDPA) were synthesized from 3‐chlorophthalic anhydride and 4‐chlorophthalic anhydride. A series of polyimides derived from the isomeric diphenylthioether dianhydrides with several diamines were prepared. The properties, such as the solubility, thermal and mechanical behavior, dynamic mechanical behavior, wide‐angle X‐ray diffraction, and permeability to some gases, were compared among the isomeric polyimides. Both 3,3′‐TDPA‐ and 3,4′‐TDPA‐based polyimides had good solubility in polar aprotic solvents and phenols. The 5% weight loss temperatures of all the obtained polyimides was near 500 °C in nitrogen. The glass‐transition temperatures decreased according to the order of the polyimides based on 3,3′‐TDPA, 3,4′‐TDPA, and 4,4′‐TDPA. The 3,4′‐TDPA‐based polyimides had the best permeability and lowest permselectivity, whereas the 4,4′‐TDPA‐based polyimides had the highest permselectivity and the lowest permeability of the three isomers. Furthermore, the rheological properties of thermoplastic polyimide resins based on the isomeric diphenylthioether dianhydrides were investigated, and they showed that polyimide 3,4′‐TDPA/4,4‐oxydianiline had the lowest melt viscosity among the isomers; this indicated that the melt processibility had been greatly improved. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 959–967, 2006     

Molecular Dynamics Simulation of Glass Transition Behavior of Polyimide Ensemble

The prediction of glass transition temperature from chemical structure has a great significance to select and design new high-properties materials. However, for the estimation and correlation methods, the deficiency of parameters for newer groups will lead to invalidity of Tg prediction or greater deviation from experiment. In the present work, we predicted Tg for a polyimide (PI) ensemble with rigid moieties, and analyzed structural factor that regards to the rotation barrier of the bridging…