Pore-filling membrane for direct methanol fuel cells based on sulfonated poly(styrene-ran-ethylene) and porous polyimide matrix

We have synthesized a porous co-polyimide film by coagulating a polyimide precursor in the non-solvent and thermal imidization. Factors affecting the morphology, pore size, porosity, and mechanical strength of the film were discussed. The porous polyimide matrix consists of a porous top layer and a spongy sub-structure with micropores. It is used as a porous matrix to construct sulfonated poly(styrene-ran-ethylene) (SPSE) infiltrated composite membrane for direct methanol fuel cell (DMFC) application. Due to the complete inertness to methanol and the very high mechanical strength of the polyimide matrix, the swelling of the composite membrane is greatly suppressed and the methanol crossover is also significantly reduced, while high proton conductivity is still maintained. Because of its higher proton conductivity and less methanol permeability, single fuel cell performance test demonstrated that this composite membrane outperformed Nafion membrane.

PEMFC催化剂的研究:自制Pt/C电催化剂的性质

研究了一种用于质子交换膜燃料电池(PEMFC)的自制Pt/C电催化剂(标记为THYT-1)的物理化学和电化学性质.将THYT-1电催化剂与E-TEK公司的同类电催化剂的组成、形态及电催化性能进行了比较.单电池测试结果显示,THYT-1的电催化性能优于E-TEK电催化剂.CV测试结果表明CO在这两种电催化剂上的电氧化性能相近;TEM分析表明两种催化剂上Pt晶粒在炭载体上呈均匀分布,平均粒径均为2～3nm;XPS和XRD测试结果表明两种催化剂中Pt主要以金属态存在.这些数据表明THYT-1催化剂的物理化学性质与E-TEK公司的相类似.

Determination of ultra-trace rare-earth elements in human plasma by inductively coupled plasma mass spectrometry

Inductively coupled plasma mass spectrometry (ICP-MS),a highly sensitive inorgnic analytic technique,fits to determine ultra-nace rare-earth elements in human plasma. Under the optimized conditions detection limits for 15 rare-earth elements are in the range of 0.7 (for Eu)-5.4 (for Gd) ng.L-1. Indium as an internal standard element is used to compensate for matrix suppression effect and sensitivity drift. Three kinds of preparation methods, diluted with 1% HNO3, digested with HNO3-H2O2 and with HNO3-HClO4, are checked and compared,and the former is the simplest way to be measured. The samples diluted with 1% HNO3, stored in 4 degrees C, are very steady for 16 days. With the method, 11 healthy plasma samples in Changchun area of China are analysed.

人体血浆中15种超痕量稀土元素的电感耦合等离子体质谱法测定

本文用电感耦合等离子体质谱法测定了人体血浆中的稀土元素。在优化的条件下 ,以内标法测得的各种纯水溶液的检测限在 0 .7(Eu)～ 5 .4(Gd) ng·L- 1范围内。研究了 K,Na,Ca,Fe等基体元素对稀土测定的影响。以 In为内标元素补偿样品基体效应以及灵敏度飘移。比较了直接稀释、HNO3- H2 O2 消解及 HNO3-HCl O4消解 3种样品处理方法 ,用 1% HNO3直接稀释样品可满足轻稀土元素的定量分析要求 ,方法的定量测定下限≤ 1μg·L- 1。

A rule to design high spin molecules with hetero-spin centers

The series of biradicals with m-phenylene coupling unit and hetero-spin centers were calculated compared with those possessing home-spin centers using AM1-CI method. A simple rule was proposed to design high spin molecules with ferromagnetic coupling unit and hetero-spin centers. Two neutral (or charged) hetero-spin centers resulted in high spin ground state, one neutral and another charged hetero-spin centers correspond to low spin ground state. The latter was ascribed to the huge splitting of two partially occupied molecular orbitals.

Synthesis and characterization of poly(amide imide)s containing cyclohexylidene moieties with bulky substituents

Novel poly(amide imide)s (PAI) containing alkyl-substituted cyclohexylidene moieties were synthesized by conventional polycondensation of trimellitic anhydride chloride with novel aromatic diamines followed by chemical imidization using acetic anhydride and pyridine. The inherent viscosities of the resulting PAIs are relatively high and range from 71 to 112 mt g(-1). The prepared PAIs show excellent thermal stability and good solubility. The glass transition temperatures (T-g) measured by DSC are observed in the range of 312-342 degrees C. Furthermore, all the polymers are readily soluble in less hygroscopic organic solvents like cyclohexanone, gamma-butyrolactone as well as aprotic polar solvents.

聚烯烃／极性聚合物界面的分子状态

为了克服高分子共混物界面不易表征的缺点，提出用溶剂选择性溶解方法使界面暴露．结合Ｘ－射线光电子能谱（ＸＰＳ）表征手段，研究了官能化聚合物，接枝型共聚物及带有反应性基团的聚合物作为共混物增容剂时在界面区域的分子状态．实验结果表明，作增容剂时，官能化聚合物在界面区内采取最有利的分子构象，充分发挥增容作用；接枝型共聚物主链、侧链向相应本体聚合物内扩散；而带有反应性基团的聚合物与某个本体聚合物发生反应之前存在反应基团在界面富集的过程

Preparation and characterization of polymer-supported rare earth complexes

The polymers containing different ligand groups of atoms (mainly O, N, and S) and their rare earth complexes were prepared, characterized and classified based on the type of metal-ligand tending. The catalytic activities of the complexes are briefly discussed. The polymer-supported rare earth complexes showed much greater activities than the corresponding complexes with a low molecular weight.

Synthesis and properties of thermotropic liquid crystalline copolyesters containing bis(4-hydroxyphenyl)methanone(IV)

A series of thermotropic liquid crystalline copolyesters were synthesized by thermal polycondensation of p-hydroxybenzoic acid, terephthalic acid, bis (4-hydroxyphenyl) methanone and diols. The resulting copolyesters were characterized by WAXD,DSC and PLM. All the copolyesters formed a nematic phase.

不对称取代钛茂/甲基铝氧烷催化体系丙烯聚合立构控制

利用一种新合成途径制备了单取代钛茂化合物(η~5-环戊二烯)[η~5-(1-(4-甲氧基苯基)环已烯基)环戊二烯]二氯化钛(Ⅰ),以衍射法确定其晶体结构属正交晶系,空间群P2_12_12_1,晶胞参数a=0.9680(5)nm,b=1.2846(5)nm,c=1.6944(6)nm,Z=4,R=0.066.详尽考察了不同聚合温度条件下Ⅰ/甲基铝氧烷(MAO)催化体系对丙烯聚合的立体化学控制,发现随着聚合温度的变化,能够生成等规、无规、间规三种不同立构取向的聚丙烯;其中等规、间规聚丙烯是由对映结构活性中心及链末端共同控制生成,而无规聚丙烯则受Bernoullian生成方式控制.

电化学扫描隧道显微镜的研制及银、镍的现场电沉积研究

本文报道电化学扫描隧道显微镜(ECSTM)的研制技术,包括电子线路及绝缘探针尖的制备。研制的ECSTM中,试样和探针的电位能同时控制。绝缘探针的制备包括先用电化学腐蚀形成针尖,然后再在光学显微镜下绝缘,用扫描电子显微镜评定了绝缘针尖的性能。最后用研制的ECSTM现场研究了银、镍在高定向裂解石墨(HOPG)上的电沉积。