反式1，4-聚丁二烯的形态和结构研究

高分子材料一般都具有某种特定的结构，这种结构将直接决定着材料的性能。当高聚物从一种结构变为另一种结构时，其材料的性能将发生改变。近来，M.Hikosaka根据聚乙烯结晶的特点，提出了“链滑移扩散理论”，认为对聚合物热处理时，其晶体片层增厚快慢与分子链的滑移扩散能力有关。反式1,4-聚丁二烯(TPBD)在常压下能以六方相稳定存在，是少有的几种具有六方相结构的聚合物。因为其六方相分子链具有较高的构象数，而各个构象之间由于能垒相差不大，构象之间很容易发生转变；因而分子链运动时相对容易，决定了六方相分子链之间的滑移扩散能力较强。为了验证M.Hikosaka的理论，特对样品在六方相温度范围进行热处理。另外由于TPBD在不同的温度下能以两种晶型稳定存在，这两种晶型之间是怎样转变的也是我们关心的问题，而且通过电镜第一次摄得了单斜相和六方相共存的电子衍射。针对上述问题我们进行了下列研究。(1)以三氯化钒体系，稀土催化剂体系合成了两种分子量的反式1,4-聚丁二烯，用IR，NMR分析高分子量样品的反式1,4结构含量为96.2%，低分子量样品反式l,4结构含量为91.2%。对两种分子量样品进行DSC研究，结果表明低分子量样品的转变温度。熔融温度均比高分子量样品低；用Thomoson-Gibbs方程计算了该样品的片层厚度，并与样品的SAXS实验结果对照，认为这种转变温度和熔点的差异除了与1,2-结构的含量有关外，也与不同分子量具有不同的片层厚度有很大关系。(2)对不同分子量的TPBD进行WAXD实验，研究了其在不同温度下的相行为及单斜相向六方相的相转变过程。以PLM为手段跟踪观察了低分子量样品的相态转变，发现许多晶粒在相转变时从视场中消失。用电镜观察到了单斜相电子衍射，六方相电子衍射及单斜相和六方相共存的电子衍射， 并发现两相结构的形貌没有大的差别。(3)用Cerius~2软件模拟了单斜相结构和六方相结构的分子链堆砌，认为单斜相向六方相发生转变时，六方相分子链构象与单斜相分子链构象相比，有序度较低，从而使其堆砌结构变得松散。同时也模拟了单斜相和六方相在晶带轴为[001]方向的电子衍射，实验观察只能得到计算机模拟所得的单斜相和六方相内层的几个电子衍射点。(4)对低分子量样品在64 ℃热处理1小时后进行的DSC，WAXD，SAXS研究表明，样品的片层厚度显著增大，结晶度也相应提高。(5)研究了高分子量样品在85 ℃和低分子量样品在53 ℃热处理不同时间后，所得的DSC曲线。结果表明随时间增加，TPBD的转变峰温度值明显增加；而且发现在前5分钟内处理样品时，结晶度都有明显增加，处理样品5分钟以后结晶度增长缓慢。对高分子量样品四次升降温时，发现降温曲线有肩峰出现，但升温曲线没有肩峰出现，把肩峰的出现归结于有小尺寸亚稳定晶体的形成。(6)对高分子量样品的六方相等温结晶数据及对由熔体快速冷却到一定温度生成单斜相的等温结晶数据进行处理，得到平衡熔点为476K，比文献值高。并利用Thomoson-Gibbs方程，得到了单斜相和六方相的温度对尺寸倒数的相图，确定了在一定尺寸下单斜相和六方相稳定存在的温度范围。(7)用电镜观察了在70 ℃热处理不同时间后所得形貌图，并讨论了样品在六方相中热处理时，样品聚集体的聚集方式。(8)研究了两种分子量样品溶液结晶时所得的球晶形貌，发现其结晶形貌与分子量有关，而且发现摄得的电子衍射是六方相电子衍射，而不是室温下稳定存在的单斜相电子衍射，认为是由于电子辐照使样品升温而发生了晶型转变。(9)用修饰后的Avrami方程，Ozawa，方程分别处理了TPBD非等温结晶数据，由Jeziorny修饰的Avrami方程分析显示TPBD的非等温结晶明显地分为一次结晶和二次结晶两个阶段，指数值n意味着一次结晶和二次结晶的成核种类，Ozawa方程分析不能很好地适用于TPBD的六方相非等温结晶数据，主要是由于Ozawa理论的不精确假定，如二次结晶，结晶温度对片层厚度相关性及整个结晶过程中恒定的冷却函数等。并由Kissinger方程得到六方相的结晶活化能为167.9kJ/mol。

钯/铁双金属对土壤中2,2′,3,4,4′,5,5′-七氯联苯的催化脱氯研究

采用Fe0还原、钯催化法对土壤中2,2′,3,4,4′,5,5′-七氯联苯的的还原特性进行了实验研究.结果表明,Pd/Fe双金属能有效地进行2,2′,3,4,4′,5,5′-七氯联苯的催化脱氯.在钯化率为0.05%、钯/铁加入量1 g、初始pH为5.6、反应时间5 d的条件下,钯/铁双金属对土壤中2,2′,3,4,4′,5,5′-七氯联苯去除率达54%.实验还考察了钯化率、初始pH、反应时间、钯/铁投加量、2,2′,3,4,4′,5,5′-七氯联苯初始浓度等参数对2,2′,3,4,4′,5,5′-七氯联苯脱氯效果的影响.研究表明,较高的钯化率、钯/铁加入量,较低的2,2′,3,4,4′,5,5′-七氯联苯初始浓度及弱酸性等条件更有利于Pd/Fe对2,2′,3,4,4′,5,5′-七氯联苯的还原脱氯.在Pd/Fe双金属表面,2,2′,3,4,4′,5,5′-七氯联苯的脱氯符合一级动力学反应,反应速率常数为0.014 2/h,其半衰期为49 h.利用实验数据,对钯/铁双金属作用下的2,2′,3,4,4′,5,5′-七氯联苯还原脱氯的反应机制也进行了分析.

均相钕系催化剂合成窄相对分子质量分布的高顺式-1，4-聚丁二烯

考察了由Nd（vers）3（简称Nd）、Al（i—Bu）2H（简称Al）和Al（i—Bu）2Cl（简称Cl）组成的均相催化剂体系在5L釜中于70℃聚合丁二烯的反应规律，并在2m^3装置上进行了放大试验。结果表明，该均相钕系催化剂具有高的稳定性；Al／Nd（摩尔比）是影响相对分子质量分布的重要因素，当Al／Nd低于20时，产物的相对分子质量分布在3．00以下；改变Nd／Bd（摩尔比）或使用不同组成的Al，可改变聚合产物的门尼黏度，但对相对分子质量分布无明显影响。在2m^3装置上，采用均相钕系催化剂可以得到收率大于90％、相对分子质量分布小于3.00和顺式-1，4-结构摩尔分数大于97．0％的聚丁二烯

The synthesis and characterization of novel liquid crystalline, meso-tetra[4-(3,4,5-trialkoxybenzoate)phenyl]porphyrins

Five, novel, meso-tetra[4-(3,4,5-trialkoxybenzoate)phenyl]porphyrins and their metal complexes were synthesized and their molecular structures were confirmed by H-1 NMR, FTIR spectroscopy and elemental analysis. Mesomorphic studies using DSC, polarizing optical microscope and X-ray diffraction revealed that all compounds exhibited thermotropic columnar mesophases over a wide mesophase temperature range and low liquid crystalline-crystal line transition temperature. (c) 2007 Elsevier Ltd. All rights reserved

Highly cis-1,4 selective polymerization of dienes with homogeneous Ziegler-Natta catalysts based on NCN-pincer rare earth metal dichioride precursors

The first aryldiimine NCN-pincer ligated rare earth metal dichlorides (2,6-(2,6-C6H3R2N=CH)(2)C6H3)LnCl(2)(THF)(2) (Ln = Y, R = Me (1), Et (2), Pr (3); R = Et, Ln = La (4), Nd (5), Gd (6), Sm (7), Eu (8), Tb (9), Dy (10), Ho (11), Yb (12), Lu (13)) were successfully synthesized via transmetalation between 2,6-(2,6-C2H3-R2N=CH)(2)-C6H3Li and LnCl(3)(THF)(1 similar to 3.5). These complexes are isostructural monomers with two coordinating THF molecules, where the pincer ligand coordinates to the central metal ion in a kappa C:kappa N: kappa N' tridentate mode, adopting a meridional geometry.

Polyimides Derived from 1,4-Bis [3-oxy-(N-aminophthalimide)] Benzene

A novel diamine, 1,4-bis [3-oxy-(N-aminophthalimide)] benzene (BOAPIB), was synthesized from 1,4-bis [3-oxy-(N-phenylphthalimide)] benzene and hydrazine. Its structure was determined via IR, H-1 NMR, and elemental analysis. A series of five-member ring, hydrazine-based polyimides were prepared from this diamine and various aromatic dianhydrides via one-step polycondensation in p-chlorophenol. The inherent viscosities of these polyimides were in the range of 0.17-0.61 dL/g. These polymers were soluble in polar aprotic solvents and phenols at room temperature. Thermogravimetric analysis (TGA) showed that the 5% weight-loss temperatures of the polyimides were near 450 degrees C in air and 500 degrees C in nitrogen. Dynamic mechanical thermal analysis (DMTA) indicated that the glass-transition temperatures (T(g)s) of these polymers were in the range of 265-360 degrees C. The wide-angle X-ray diffraction showed that all the polyimides were amorphous.

Polyamide thin film composite membranes prepared from 3,4',5-biphenyl triacyl chloride, 3,3',5,5'-biphenyl tetraacyl chloride and m-phenylenediamine

Two novel of tri- and tetra-functional biphenyl acid chloride: 3,4',5-biphenyl triacyl chloride (BTRC) and 3,3',5,5'-biphenyl tetraacyl chloride (BTEC), were synthesized, and used as new monomers for the preparations of the thin film composite (TFC) reverse osmosis (RO) membranes. The TFC RO membranes were prepared on a polysulfone supporting film through interfacial polymerization with the two new monomers and m-phenylenediamine (MPD). The membranes were characterized for the permeation properties, chemical composition, d-space between polymer chains, hydrophilicity, membrane morphology including top surface and cross-section. Permeation experiment was employed to evaluate the membranes performance including salt rejection and water flux. The surface structure and chemical composition of membranes were analyzed by attenuated total reflectance infrared (ATR-IR) and X-ray photoelectronic spectroscopy (XPS). The results revealed that the active layer of membranes was composed of highly cross-linked aromatic polyamide with the functional acylamide (-CONH-) bonds. The TFC membranes prepared from biphenyl acid chloride exhibit higher salt rejection compared with that prepared from trimesoyl chloride (TMC) at the expanse of some flux.

Synthesis and properties of novel organosoluble polyimides derived from 1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride and various aromatic diamines

A novel triptycene-based dianhydride, 1,4-bis[4-(3,4-dicarboxylphenoxy)]triptycene dianhydride, was prepared from 4-nitro-N-methylphthalimide and potassium phenolate of 1,4-dihydroxytriptycene (1). The aromatic nucleophilic substitution reaction between 4-nitro-N-methylphthalimide and I afforded triptycene-based bis(N-methylphthalimide) (2), which hydrolyzed and subsequently dehydrated to give the corresponding dianhydride (3). A series of new polyimides containing triptycene moieties were prepared from the dianhydride monomer (3) and various diamines in in-cresol via conventional one-step polycondensation method. Most of the resulting polyimides were soluble in common organic solvents, such as chloroform, THF, DMAc and DMSO. The polyimides exhibited excellent thermal and thermo-oxidative stabilities with the onset decomposition temperature and 10% weight loss temperature ranging from 448 to 486 degrees C and 526 to 565 degrees C in nitrogen atmosphere, respectively. The glass transition temperatures of the polyimides were in the range of 221-296 degrees C. The polyimide films were found to be transparent, flexible, and tough. The films had tensile strengths, elongations at break, and tensile moduli in the ranges 95-118 MPa, 5.3-16.2%, and 1.03-1.38 GPa, respectively. Wide-angle X-ray diffraction measurements revealed that these polyimides were amorphous.

Water resistant sulfonated polyimides based on 4,4'-binaphthyl-1,1',8,8'-tetracarboxylic dianhydride (BNTDA) for proton exchange membranes

A series of sulfonated polyimides (SPIs) were synthesized in in-cresol from 4,4'-binaphthyl- 1,11,8,8'-tetracarboxylic dianhydride (BNTDA), 4.4'-diaminodiphenylether-2,2-disulfonicacid (ODADS), and 4.4'-diamino-diphenyl ether (ODA) in the presence of triethylamine and benzoic acid. The resulted polyimides showed much better water resistance than the corresponding sulfonated polyimides from 1,4,5,8-naphthatenetetracarboxylic dianhydride (NTDA) and ODADS, which is contributed to the higher electron density in the carbonyl carbon atoms of BNTDA. Copolyimides S-75 and S-50 maintained their mechanical properties and proton conductivities after aging in water at 100 degrees C for 800 h. The proton conductivity of these SPIs was 0.0250-0.3565 S/cm at 20 degrees C and 100% relative humidity (RH), and increased to 0.11490.9470 S/cm at 80 degrees C and 100% RH. The methanol permeability values of these SPIs were in the range of 0.99-2.36 x 10(-7) cm(2)/S, which are much lower than that of Nafion 117 (2 x 10(-6) cm(2)/s).

Preparation, structure and oxide ion conductivity in Ce6-xYxMoO15-delta (x=0.1-1.4) solid solutions

The Ce6-xYxMoO15-delta solid solution with fluorite-related structure have been characterized by differential thermal analysis/thermogravimetry (DTA/TG), X-ray diffraction (XRD), IR, Raman, scanning electric microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods. The electric conductivity of samples is investigated by Ac impedance spectroscopy. An essentially pure oxide-ion conductivity of the oxygen-deficiency was observed in pure argon, oxygen and air. The highest oxygen-ion conductivity was found in Ce5.5Y0.5MoO15-delta ranging from 5.9 X 10(-5)(S cm(-1)) at 300 degrees C to 1.3 X 10(-2)(S cm(-1)) at 650 degrees C, respectively. The oxide-ion conductivities remained stable over 80 h-long test at 800 degrees C. These properties suggested that significant oxide-ionic conductivity exists in these materials at moderately elevated temperatures.

Effect of La/Ce ratio on the structure and electrochemical characteristics of La0.7-xCexMg0.3Ni2.8Co0.5 (x=0. 1-0.5) hydrogen storage alloys

The effect of La/Ce ratio on the structure and electrochemical characteristics of the La0.7-xCexMg0.3Ni2.8Co0.5 (x = 0.1, 0.2, 0.3, 0.4, 0.5) alloys has been studied systematically. The result of the Rietveld analyses shows that, except for small amount of impurity phases including LaNi and LaNi2, all these alloys mainly consist of two phases: the La(La, Mg)(2)Ni-9 phase with the rhombohedral PuNi3-type structure and the LaNi5 phase with the hexagonal CaCU5-type structure. The abundance of the La(La, Mg)(2)Ni-9 phase decreases with increasing cerium content whereas the LaNi5 phase increases with increasing Ce content, moreover, both the a and cell volumes of the two phases decrease with the increase of Ce content. The maximum discharge capacity decreases from 367.5 mAh g(-1) (x = 0.1) to 68.3 mAh g(-1) (x = 0.5) but the cycling life gradually improve. As the discharge current density is 1200 mA g(-1), the HRD increases from 55.4% (x = 0.1) to 67.5% (x = 0.3) and then decreases to 52.1% (x = 0.5). The cell volume reduction with increasing x is detrimental to hydrogen diffusion D and accordingly decreases the low temperature dischargeability of the La0.7-xCexMg0.3Ni2.8Co0.5 (x = 0.1-0.5) alloy electrodes.

Novel hole-transporting materials based on 1,4-bis(carbazolyl)benzene for organic light-emitting devices

Novel hole-transporting molecules containing 1,4-bis(carbazolyl)benzene as a central unit and different numbers of diphenylamine moieties as the peripheral groups have been synthesized and characterized. These compounds are thermally stable with high glass transition temperatures of 141-157 degreesC and exhibit chemically reversible redox processes. Their amorphous state stability and hole transport properties can be significantly improved by increasing the number of diphenylamine moieties in the outer part and by controlling the symmetry of the carbazole-based molecules. These compounds can be used as good hole-tran sporting materials for organic electroluminescent (EL) devices. The device performance based on tri- and tetra-substituted carbazole derivatives is comparable to that of a typical 4,4'-bis[N-(1-naphthyl)-N-phenylamino] biphenyl (NPB)-based device.

Synthesis and properties of soluble polyimides based on isomeric ditrifluoromethyl substituted 1,4-bis(4-aminophenoxy)benzene

A new fluorinated diamine monomer, [1,4-bis(4-amino-3-trifluoromethylphenoxy)benzene (2)], and a known isomeric analog 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (3) were synthesized. A series of organosoluble polyimides Ia-d and IIa were prepared from the diamines (2, 3) and dianhydrides (a-d) by a high-temperature one-step method. The effects of the trifluoromethyl substituents on the properties of polyimides were evaluated through the study of their soluble, thermal, optical, and gas permeability properties. Polyimides (Ia-d) had glass transition temperatures between 229 and 279 degrees C, and the temperatures at 5% weight loss ranged from 510 to 533 degrees C under nitrogen. These polyimides could be cast into flexible and tough membranes from DMAc solutions. The membranes had tensile strengths in the range of 137-169 MPa, tensile modulus in the range of 1.6-2.2 GPa and elongations at break from 11% to 14%. The polyimide la with trifluoromethyl groups ortho to the imide nitrogen exhibited enhanced gas permeability, solubility, transparency, and thermal stability compared with the isomeric polyimide IIa with the CF3 group meta to the imide nitrogen.

Column chromatographic purification free synthesis of long-chain monodisperse oligo(1,4-phenyleneethynylene)s: towards large-scale automatic synthesis of molecular wires

A facile, mild and rapid solid phase synthetic route free of column chromatographic purification to the synthesis of soluble monodisperse long-chain oligo(1,4-phenyleneethynylene)s is presented.

橘红色发光的八羟基喹啉锌和1,4-二乙烯基苯的交替共聚物

经由配位聚合反应 ,合成了八羟基喹啉锌和 1 ,4 二乙烯基苯的交替共聚物。所合成的聚合物通过元素分析和红外光谱进行了表征。在 36 5nm的紫外光照射下 ,聚合物呈现强的橘红色发光 ,在乙氰溶液中的最大发光峰位在 5 71nm。热失重分析表明 ,这种含Znq2 的聚合物具有稳定的热力学性质 ,热失重 5 %的温度大于 4 39℃。这种聚合物的电致发光性质正在研究中