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81.
Baijun Liu Gilles P. Robertson Michael D. Guiver Yi‐Ming Sun Yin‐Ling Liu Juin‐Yih Lai Serguei Mikhailenko Serge Kaliaguine 《Journal of Polymer Science.Polymer Physics》2006,44(16):2299-2310
A series of sulfonated poly(aryl ether ether ketone ketone)s statistical copolymers with high molecular weights were synthesized via an aromatic nucleophilic substitution polymerization. The sulfonation content (SC), defined as the number of sulfonic acid groups contained in an average repeat unit, could be controlled by the feed ratios of monomers. Flexible and strong membranes in sodium sulfonate form could be prepared by the solution casting method, and readily transformed to their proton forms by treating them in 2 N sulfuric acid. The polymers showed high Tgs, which increased with an increase in SC. Membranes prepared from the present sulfonated poly(ether ether ketone ketone) copolymers containing the hexafluoroisopropylidene moiety (SPEEKK‐6F) and copolymers containing the pendant 3,5‐ditrifluoromethylphenyl moiety (SPEEKK‐6FP) had lower water uptakes and lower swelling ratios in comparison with previously prepared copolymers containing 6F units. All of the polymers possessed proton conductivities higher than 1 × 10?2 S/cm at room temperature, and proton conductivity values of several polymers were comparable to that of Nafion at high relative humidity. Their thermal stability, oxidative stability, and mechanical properties were also evaluated. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2299–2310, 2006 相似文献
82.
Two novel dithienylethenes with ferrocene units were synthesized by Wittig reaction. The structure of 2a has been established by X‐ray diffraction studies. They could reversibly interconvert between two thermally stable forms, an open and a closed one, using light of different wavelengths as triggers. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
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85.
纳秒级激光闪光光解装置可用于有机光化学、光物理过程,瞬态发光和吸收的动力学过程的研究,在不改变原装置整体布局和结构的基础上,建立了有机非线性光学材料的二阶非线性系数测定方法,并为国家863专家委员会承担过仲裁测定。 相似文献
86.
聚合物电致发光材料研究进展 总被引:5,自引:0,他引:5
本文较详细地综述了聚合物电致发光材料的研究进展,重点介绍了聚对苯撑乙烯(PPV),并提出了有关聚合物电致发光材料及器件构造研究的一些观点。 相似文献
87.
X荧光滤纸片薄样法测定铅锌矿选矿流程样中Pb,Zn,Cu,Fe 总被引:3,自引:1,他引:3
本法将X荧光滤纸片薄样法用于具有复杂组分的铅锌矿选矿样品中Pb,Zn,Cu,Fe的分析,样品经化学溶样后滴于定量滤纸片上,标准样品可直接用纯试剂人工配制,用同样制成滤纸片薄样标准系列,因薄样测定可不作基体效应校正,标样使用数量少,又无需化学法标定。故方法实验周期短,样品测定手续简便快速,元素分析含量适应范围宽,可适用于组分复杂,元素含量变化范围大的试样分析,样品分析结果与化学法相符,方法准确度与精 相似文献
88.
A binuclear complex [Cu2(DTB)(DMF)4(H2O)]·2DMF (DTB = 1,4-dinitro-2,3,5,6-tetracarboxylatobenzenic anion; DMF = N,N-dimethylformamide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex Cu ion is located in a distorted square pyramidal environment with two oxygen atoms O(1) and O(3) from two carboxylate groups, another two oxygen atoms O(7) and O(8) from terminal ligands of two DMF molecules, and a fifth coordinated oxygen atom O(9) from the terminal ligand of one H2O molecule, in which the O(8) atom is situated in the apex of the pyramid. DTB as bridging ligand coordinates two Cu ions through its four carboxylate groups. The variable-temperature magnetic susceptibility of the complex was measured in the 5–300 K range. The magnetic coupling parameter is consistent with a ferromagnetic exchange between the two copper(II) centers and the data fit a binuclear magnetic exchange model based on the Hamiltonian operator ( = -2J12, 1 = 2= 1/2), giving the ferromagnetic coupling parameter of 2J = 1.80 cm- 1. This is the first example of a tetracarboxylatobenzenic bridging complex exhibiting ferromagnetic interaction. 相似文献
89.
Juan?Feng Qian?Wang Xujia?Zhang Youguo?Huang Xicheng?Ai Xingkang?Zhang Jianping?ZhangEmail author 《中国科学B辑(英文版)》2004,47(1):80-90
The LH2 complex from Rhodopsudomonas (Rps.) palustris is unique in the heterogeneous carotenoid compositions. The dynamics of triplet excited state Carotenoids (3Car* has been investigated by means of sub-microsecond time-resolved absorption spectroscopy both at physiological temperature
(295 K) and at cryogenic temperature (77K). Broad and asymmetric T
n
←T
1 transient absorption was observed at room temperature following the photo-excitation of Car at 532 nm, which suggests the
contribution from various carotenoid compositions having different numbers of conjugated C=C double bonds (Nc=c). The triplet absorption bands of different carotenoids, which superimposed at room temperature, could be clearly distinguished
upon decreasing the temperature down to 77 K. At room temperature the shorter-wavelength side of the main Tn04T1 absorption band decayed rapidly to reach a spectral equilibration with a characteristic time constant of ∽1 μs, the same
spectral dynamics, however, was not observed at 77 K. The aforementioned spectral dynamics can be explained in terms of the
triplet-excitation transfer among heterogeneous carotenoid compositions. Global spectral analysis was applied to the time-resolved
spectra at room temperature, which revealed two spectral components peaked at 545 and 565 nm, and assignable to the Tn04 T1 absorption of Cars with Nc=c=11 and Nc=c=13, respectively. Surprisingly, the decay time constant of a shorter-conjugated
Car, i.e. 0.72 ώs (aerobic) and 1.36 ώs (anaerobic), is smaller than that of a longer-conjugated Car, i.e. 2.12 us (aerobic)
and 3.75 ώs (anaerobic), which is contradictory to the general rule of carotenoids and relative polyenes. The results are
explained in terms of triplet-excitation transfer among different types of Cars. It is postulated that two Cars with different
conjugation lengths coexist in an α, β-subunit in the LH2 complex. 相似文献
90.
A novel method for preparing silver nanoelectrode ensembles(SNEEs) and gold nanoelectrode ensembles (GNEEs) has been developed. Silver colloid particles were first absorbed to the gold electrode surface to form a monolayer silver colloid. N-hexadecyl nercaptan was then assembled on the electrode to form a thoil monolayer on which hydrophilic ions cannot be transfered. The SNEEs was prepared by removing thiol from silver colloid surface through applying and AC voltage with increasing frequency at 0.20V(vs.SCE). Finally,GNEEs was obtained by immersing a SNEEs into 6 mol/L HNO3 to remove the silver colloid particles. By comparison with other methods such as template method ect., this method enjoys some advantages of lower resistance, same diameter,easy preparation,controllable size and density. 相似文献