牵伸倍率对联苯型聚酰亚胺纤维形貌、取向及性能的影响

均苯四甲酸二酐(PMDA)和联苯二酐(BPDA)与3,3′-二甲基联苯二胺(OTOL)共聚得到聚酰亚胺(PI)溶液,通过干喷-湿法纺制成纤维.利用扫描电镜(SEM)、广角X射线衍射(WAXD)、纤维力学性能测试仪、动态力学分析仪(DMA)和热失重分析仪(TGA)等表征手段,研究不同牵伸倍率对联苯型聚酰亚胺纤维形貌结构、...     

基于柔性羧酸配体和含氮辅助配体的金属有机配位聚合物的合成、结构及表征（英文）

本文通过水热法制备得到了一个新型二维金属有机配位聚合物[Co2(L1)(4,4’-bipy)(3H2O)·2H2O]n(1,H4L1=3,3’-(1,4-苯二氧基)二邻苯二甲酸;4,4’-bipy=4,4’-联吡啶),并对其结构进行了系统的表征。研究表明,3,3’-(1,4-苯二氧基)二邻苯二甲酸配体中的羧酸采用μ1-η1-η0和μ1-η1-η1两种桥联方式与2个钴离子配位形成十四圆环,形成的十四圆环被3,3’-(1,4-苯二氧基)二邻苯二甲酸配体连接进一步形成之字形的一维链状结构。最终,辅助配体4,4’-联吡啶将这些一维链状结构连接起来形成二维的(44)-sql网状拓扑结构。在本文中,我们还进一步研究了配位聚合物1的红外光谱以及热稳定性。     

基于柔性羧酸配体和含氮辅助配体的金属有机配位聚合物的合成、结构及表征

本文通过水热合成的方法制备得到了一个新型的二维金属有机配位聚合物[Co2(L1)(4,4’-bipy)(3H2O).2H2O]n (1), (H4L1 = 3,3'-(1,4-苯二氧基)二邻苯二甲酸; 4,4’-bipy = 4,4’-联吡啶),并对其结构进行了系统的表征。研究表明3,3'-(1,4-苯二氧基)二邻苯二甲酸配体中的羧酸采用μ1-η1-η0和μ1-η1-η1两种桥联的方式跟两个钴离子配位形成十四圆环,形成的十四圆环被3,3'-(1,4-苯二氧基)二邻苯二甲酸配体连接进一步形成之字形的一维链状结构。最终,辅助配体4,4’-联吡啶将这些一维链状结构连接起来形成二维的(44)-sql网状拓扑结构。在本文中,我们还一步研究了这个配位聚合物的红外光谱以及热稳定性。     

含二苯胺2,6-二咔唑基吡啶共轭化合物的合成

以咔唑,2,6-二溴吡啶和二苯胺为原料,经Ullmann和碘代反应合成了4个含二苯胺2,6-二咔唑基吡啶共轭化合物:3-二苯胺基-2,6二咔唑基吡啶,3,3’-二(二苯胺基)-2,6-二咔唑基吡啶,3,3’,6-三(二苯胺基)-2,6-二咔唑基吡啶和3,3’,6,6’-四(二苯胺基)-2,6-二咔唑基吡啶,其结构经1H NMR和IR确证。     

新型六[间-(β-噻吩基)苯基]苯衍生物的合成

3,3’-二溴二苯乙炔与β-噻吩频哪醇硼酸酯发生Suzuki偶联反应制得3,3’-二(2,5-二十二烷基-3-噻吩)二苯乙炔(7);Co2(CO)8催化7自身环三聚合成了新型六[间-(β-噻吩基)苯基]苯衍生物——六{3-[2’,5’-二(十二烷基)-3-噻吩]苯基}苯,产率86%,其结构经1H NMR和MS表征。     

水热法制备ZnS:Cu,Al纳米X射线发光粉及其光谱特性

采用水热法低温(200℃)处理12h直接制备ZnS∶Cu,Al纳米晶,并探讨其光致(PL)和X射线激发(XEL)光谱特性及后续退火处理的影响.XRD和TEM分析表明,水热法直接制备的ZnS∶Cu,Al粒径约为15nm,尺寸分布窄,分散性好,具有纯立方相的球形结构.其PL和XEL光谱均为宽带谱,n(Cu)/n(Zn)=3×10-4和n(Cu)/n(Al)=0.5时PL和XEL光谱强度最大,XEL峰值在470nm处.在此条件下,水热处理3h直接合成的纳米晶在氩气保护下于800℃退火1h后样品的XEL发光进一步增强.XEL光谱强度约是退火前样品的8倍,此时峰值波长在520nm,团聚形成径为200～500nm的类球形六方相结构.发光强度增强,但粒径很小,对提高成像系统分辨率非常有意义.通过比较样品的XEL和PL光谱,讨论了XEL和PL光谱的发光机理和激发机制及退火对其特性的影响.     

一种新型氧氮杂大环化合物的光合成

以乙腈为溶剂,二苯甲酮为光敏化剂,6,6’-二甲基-4,4’-(三亚甲二氧基)-二-2-吡喃酮与N,N’-亚甲基双丙烯酰胺经光二重[2+2]环加成反应,位置选择性地合成了一种新型氧氮杂大环化合物,其结构经1H NMR,12C NMR,FT-IR和HR-MS表征。最佳光反应条件为:1 3.2 mmol,n(1)∶n(二苯甲酮)=1.0∶1.5,于300 W光照18 h,收率37%。     

二维层状硫代二丙酸桥联锌配位聚合物{[Zn(C_6H_8O_4S)(C_(10)H_8N_2)]·(H_2O)_2}_n的合成、结构与性质研究

合成了1个新的二维层状配位聚合物{[Zn(C6H8O4S)(C10H8N2)]·(H2O)2}n(C6H8O4S-=3,3’-硫代二丙酸根,C10H8N2=4,4-联吡啶),并对其进行了元素分析、红外光谱表征、TG分析和单晶X射线的表征.结果表明:该配位聚合物属单斜晶系,P2/n空间群,晶胞参数a=1.055 9(2)nm,b=0.556 98(11)nm,c=1.550 0(3)nm,β=94.82(3)°,Z=2,F(000)=448,最终R=0.062 8,wR=0.134 7.在配位聚合物分子中,锌离子与2个不同的3,3’-硫代二丙酸根中的2个羧酸O原子及2个不同的4,4’-联吡啶分子中的2个N原子配位,形成了扭曲的四面体结构.每个硫代二丙酸根桥联2个锌原子形成一维链状结构.链与链之间进一步通过4,4’-联吡啶分子连接,形成了一个二维层状结构.分子间氢键作用的结果使配合物具有三维网络结构.     

新型手性聚酰胺酰亚胺的合成及其热稳定性

L-异亮氨酸与3,3’,4,4’-联苯四甲酸二酐在乙酸中回流反应制得具有联苯酰亚胺结构的手性N,N’-(4,4’-二邻苯二甲酰基)-二[(S)-(+)-异亮氨酸](3);以3和二苯基甲烷二异氰酸酯为单体,通过缩聚反应合成了新型手性聚酰胺酰亚胺(5),其结构经1H NMR和IR表征。DSC测试结果表明,5在氮气氛中5%失重温度超过370℃;600℃时残余质量为60%,显示出良好的热稳定性。     

单向拉伸聚酰亚胺薄膜

分别以聚酰胺酸法和部分酰亚胺化的“凝胶法”研究了均苯二酐/二苯醚二胺(PMDA/ODA)和联苯二酐/对苯二胺(BPDA/PPD)体系聚酰亚胺薄膜在制膜过程中对单向拉伸比的影响,研究了薄膜在热膨胀系数和力学性能方面的差别。结果表明,“凝胶法”薄膜可以有较高的拉伸比,可以使薄膜有较低的热膨胀系数(对于PMDA/ODA,由35.1×10-6/℃降低到12.5×10-6/℃),可以明显提高拉伸方向的强度和模量,PMDA/ODA可以分别达到236MPa和1.7GPa;BPDA/PPD可以分别达到613MPa和9.3GPa,但伸长率有所降低。     

Properties,Morphology and Structure of BPDA/PPD/TFMB Polyimide Fibers

The mechanical properties of fibers were notably improved by incorporating 2,2′-bis(trifluoromethyl)- benzidine(TFMB) into 3,3′,4,4′-biphenyltetracarboxylic dianhydride(s-BPDA) and p-phenylenediamine(PPD) backbone. The best strength and modulus of BPDA/PPD/TFMB polyimide(PI) fiber(diamine molar ratio of PPD/TFMB= 90/10) were 1.60 and 90 GPa, respectively, which was over two times that of BPDA/PPD PI fiber. SEM image showed that the cross-section of fibers at each stage was round and voids free. Besides, the “skin-core” and microfibrillar structure were not observed. The thermal properties of PI fibers were also investigated. The results showed that the fibers owned excellent thermal stability, moreover, the structural homogeneity of fibers were significantly improved by heat-drawn stage. The T_g values were found to be around 300℃ by dynamic mechanical analysis(DMA). Wide angle X-ray diffraction(WAXD) and small angle X-ray scattering(SAXS) experiments indicated that the order degree of longitudinal and lateral stacks, the molecular orientation and the structural homogeneity of fibers were improved in the preparation process of fibers.     

含磷聚酰亚胺纤维的制备及其力学与阻燃性能

采用廉价的三苯基氧膦和混酸合成了一种含磷二胺单体,二（3-氨基苯基）苯基膦氧(DAPPO)。在4,4′-二胺基二苯醚（ODA）、3,3′,4,4′-联苯四酸二酐（BPDA）和均苯四酸二酐（PMDA）聚合体系中引入该单体,制备含磷聚酰亚胺纤维。热失重分析（TGA）结果表明,聚酰亚胺纤维的热稳定性随含磷量的增加而明显提高。当n（DAPPO）：n（ODA）为7：93时,纤维的极限氧指数达到了43,说明纤维的阻燃性能显著提高。     

Structure and properties of polyimide fibers containing benzimidazole and Amide Units

Co‐polyimide (co‐PI) fibers with outstanding mechanical properties were fabricated via thermal imidization of polyamic acids, derived from a new design of combining the amide and benzimidazole diamine monomers, 4‐amino‐N‐(4‐aminophenyl)benzamide (DABA) and 2‐(4‐aminophenyl)‐5‐aminobenzimidazole (BIA), with 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (BPDA). The crystalline structure and micromorphology of the prepared co‐PI fibers were investigated by synchrotron wide‐angle X‐ray diffraction (WAXD) and small‐angle X‐ray scattering (SAXS). The two‐dimensional WAXD spectra imply that the co‐PI fibers possess a structure between smectic‐like and three‐dimensionally ordered crystalline phase, and all the obtained fibers are highly oriented along the fiber axis. SAXS patterns exhibit a pair of meridional scattering streaks for the homo‐PI (BPDA/BIA) fiber, suggesting the presence of periodic lamellar structure. The incorporation of DABA into the polymer chains destroyed the lamellar structure but led to smaller size of microvoids upon increasing DABA moiety, based on SAXS analysis. The co‐PI fibers, with the molar ratio of BIA/DABA being 7/3, exhibited the optimum tensile strength and modulus of 1.96 and 108.3 GPa, respectively, attributed to the well‐defined ordered and dense structure. The chemical structure and molecular packing significantly affected the thermal stability of fibers, resulting in the different glass transition temperatures (T_g) from 350 to 380 °C. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 183–191     

含磷聚酰亚胺纤维的制备与性能

合成了一种含磷二胺单体, 二(4-胺基苯氧基)苯基膦氧(DAPOPO). 该单体与4,4'-二胺基二苯醚(ODA)、 均苯四酸二酐(PMDA)和3,3',4,4'-联苯四酸二酐(BPDA)共聚得到聚酰胺酸溶液, 通过干喷湿纺法纺丝得到聚酰胺酸纤维, 聚酰胺酸纤维经过热亚胺化和热牵伸得到含磷的聚酰亚胺纤维. 利用纤维强度仪、 扫描电子显微镜、 热失重分析仪和氧指数测定仪等研究了含磷聚酰亚胺纤维的力学性能、 形貌、 热稳定性能和阻燃性能. 结果表明, 随着含磷量的增加, 纤维的热稳定性明显提高, 而极限氧指数从35上升到了45, 说明纤维的阻燃性能得到很大提高.     

The crystal structures and thermal shrinkage properties of aromatic polyimide fibers

Three aromatic polyimides based on 3,3,4,4-biphenyl-tetracarboxylic dianhydride (BPDA) and three different diamines 2,2-bis(trifluoromethyl)-4,4-diaminobiphenyl (PFMB), 2,2-dimethyl-4, 4-diaminophenyl (DMB) or 3,3-dimethylbenzidine (OTOL) have been synthesized. These polyimides are soluble in hotp-chlorophenol,m-cresol or other phenolic solvents. Fibers have been spun from isotropic solutions using a dry-jet wet spinning method. The as-spun fibers generally exhibit low tensile properties, and can be drawn at elevated temperatures (>380° C) up to a draw ratio of 10 times. Remarkable increases in tensile strength and modulus are achieved after drawing and annealing. The crystal structures of highly drawn fibers were determinedvia wide angle X-ray diffraction (WAXD). The crystal unit cell lattices have been determined to be monoclinic for BPDA-PFMB and triclinic for both BPDA-DMB and BPDA-OTOL. Thermomechanical analysis (TMA) was used to measure thermal shrinkage stress and strain. A selfelongation has been found in the temperature region around 450°C. This phenomenon can be explained as resulting from the structural development in the fibers as evidencedvia WAXD observations.Dedicated to Profeseor Bernhard Wunderlich on the occasion of his 65th birthdayThis work was supported by SZDC's Presidential Young Investigator Award from the National Science Foundation (DMR-9175538) and NSA/EPIC/Ohio Industry Center of Molecular and Microstructure Composites at Case Westen Reserve University and The University of Akron.     

Effect of Draw Ratio on the Morphologies and Properties of BPDA/PMDA/ODA Polyimide Fibers

3,3,4,4-Biphenyltetracarboxylic dianhydride/pyromellitic dianhydride/4,4-oxydianiline（BPDA/PMDA/ODA） polyimide copolymer fibers with different draw ratios were prepared from the imidization of polyacrylic acid（PAA） fibers via a dry-jet wet-spinning process.Their morphologies,microcrystal orientations,thermal stabilities,and mechanical properties were investigated via scanning electron microscopy（SEM）,wide angle X-ray diffraction（WAXD）,thermogravimetric analysis（TGA）,and tensile experiments.In order to acquire fibers with better mechanical performance,we aimed at obtaining the optimal draw ratio.Drawing during thermal imidization resulted in a decreased diameter of fiber from 25.8 μm to 16.9 μm corresponding to draw ratio from 1 to 3.5.WAXD results show that the degree of the orientation of the undrawn sample is 64.1％,whereas that of the drawn sample is up to 82％.The as-spun fiber and those with different draw ratios all exhibit high thermal stabilities,i.e.,the temperature at a mass loss of 5％ can reach as high as 570 ℃.The tensile strengths and tensile modulus of the fibers increase with the draw ratios,and the maximum tensile strength and modulus are 0.90 and 12.61 GPa,respectively.     

Improvement of thermoplasticity for s‐BPDA/PDA by copolymerization and blend with novel asymmetric BPDA‐based polyimides

Asymmetric biphenyl type polyimides (PI) derived from 2,3,3′,4′‐biphenyltetracarboxylic dianhydride (a‐BPDA) and p‐phenylenediamine (PDA) or 4,4′‐oxydianiline (ODA) show higher T_gs, and much better thermoplasticity than the corresponding isomeric PIs from symmetric 3,3′,4,4′‐biphenyltetracarboxylic dianhydride (s‐BPDA). In addition, a‐BPDA‐derived PIs are completely amorphous owing to their bent chain structures and highly distorted conformations, whereas the PIs from s‐BPDA are semicrystalline. a‐BPDA‐derived PIs possessing these properties or the a‐BPDA monomer were used as a flexible blend component or a comonomer to improve the insufficient thermoplasticity of semirigid s‐BPDA/PDA homo polymer. The blends composed of s‐BPDA/PDA (80%) with a‐BPDA‐derived PIs (20%), as well as the s‐BPDA/PDA‐based copolymer containing 20% a‐BPDA, showed a certain extent of thermoplasticity above the T_gs without causing a decrease in T_g. In addition, these blends and copolymer provided comparatively low thermal expansion coefficient (ca. 18 ppm). The improved film properties for the blends are related to good blend miscibility. On the other hand, when s‐BPDA/ODA was used as a flexible matrix polymer instead of a‐BPDA‐derived PIs, the 80/20 blend film annealed at 400°C exhibited no prominent softening at the T_g. This result arises from annealing‐induced crystallization of the flexible s‐BPDA/ODA component. Thus, these results revealed that a‐BPDA‐derived PIs are promising candidates as matrix polymers for semirigid s‐BPDA/PDA for the present purpose. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2499–2511, 1999     

热亚胺化过程中气氛和拉力对BPDA-PDA聚酰亚胺纤维结构与性能的影响

研究了3,3',4,4'-联苯四酸二酐-对苯二胺(BPDA-PDA)型聚酰胺酸(PAA)纤维热亚胺化过程中气氛和拉力对聚酰亚胺(PI)纤维结构和性能的影响. 热处理过程中, 恒温处理5 min时, 虽然不同气氛下纤维的表面形貌并无明显差异, 但N₂气下所得纤维的力学性能明显优于空气下的样品, N₂气保护作用下, 最高断裂强度和初始模量分别达到1.25和65.0 GPa. 恒温处理40 min时, N₂气对纤维表面形貌有明显的保护作用. 但对于力学性能, 气氛的影响仅在450 ℃时表现得非常明显. 低于450 ℃时, 长时间的热处理成为影响纤维力学性能的主要因素, 气氛的影响变得不明显. 高于450 ℃时, 在N₂气和空气中的纤维皆发生明显的降解, 从而严重影响其力学性能. 热亚胺化过程中施加的拉力会促进纤维热酰亚胺化过程中的膨胀. 随着拉力的增加PI纤维长度增加, 同时直径减小. PI纤维轴上(004)晶面的间距、 晶粒尺寸、 线性热膨胀系数(为负值)的绝对值及玻璃化转变温度都随热处理时拉力的增加而增大. 纤维的断裂强度随拉力的变化基本保持在0.90 GPa左右, 断裂伸长率随着拉力增加稍有下降, 纤维的初始模量随拉力的增大而增加.     

Photophysical processes in aromatic polyimides. Studies with model compounds

Emission mechanism in an aromatic polyimide, PI(BPDA/PDA), derived from biphenyltetracarboxylic dianhydride and p-phenylene diamine were studied with ultraviolet visible absorption and fluorescence spectra of a series of the model compounds. The excitation spectrum of the intermolecular charge-transfer (CT) fluorescence peaking around 550 nm of PI(BPDA/PDA) thin film was completely consistent with the absorption spectrum, indicating that the intermolecular CT fluorescence emission of PI(BPDA/PDA) film is not caused by direct excitation of the CT absorption band, but by light absorption due to structural units in the polymer backbone. The UV-vis. absorption spectra of the model compounds corresponding to the structural units in PI(BPDA/PDA) showed that the longest wavelength absorption band is due to the biphenylbisimide moiety. The band was assigned as π, π* transition with the polarization spectrum of the model compound. The fluorescence spectra of the model compounds changed sensitively depending on the conformation around N-phenyl bond. The lifetime measurement for the model compounds suggested that intramolecular CT process occurs very rapidly. © 1993 John Wiley & Sons, Inc.