Gas transport properties of novel poly(arylene ether ketone)s containing dibenzoylbiphenyl and benzonaphthone moieties

In this work we present the results from studies on novel poly(arylene ether ketone)s, including gas permeability, wide-angle x-ray diffraction (WAXD), and dynamic mechanical analysis (DMA). Poly(arylene ether ketone)s containing 2,2′- and 3,3′-dibenzoylbiphenyl (DBBP) moieties were characterized to study the effect of biphenyl substitution on gas transport properties. Gas permeabilities of naphthalene-containing poly(arylene ether ketone)s were also measured. Higher permeabilities were observed for polymers prepared with 6F-BPA, compared to 9,9-bis(4-hydroxyphenyl)fluorene (HPF). The naphthalene-containing polymers exhibited higher permeabilities than the DBBP polymers, except for a polymer having the 2,2′-DBBP and tetramethylbiphenyl moieties. Based on our work, and results reported in the literature, the 3,3′-DBBP polymers showed the lowest permeabilities for DBBP-containing poly-(arylene ether ketone)s. The low permeabilities are due to more efficiently packed chains brought on by greater flexibility of the backbone, compared to the other polymers studied. DMA studies confirmed the higher barriers to rotation which are believed to be responsible for 2,2′-DBBP polymers having similar selectivities compared to 3,3′-DBBP polymers. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 425–431, 1998     

Dielectric and dynamic mechanical relaxation studies on poly(aryl ether ketone)s

The relaxation behavior of four amorphous poly(aryl ether ketone)s was investigated using dielectric relaxation spectroscopy and dynamic mechanical analysis. The temperature dependence of the relaxation times of the glass transition process and the cooperative nature of this process were unaffected by changes in polymer structure. The temperature location of the loss peaks for all polymers progressed smoothly between the low frequency of the mechanical measurements and the higher frequencies of the dielectric probe. Differences were observed in mechanical activation energy and dielectric relaxation strength for one polymer which contained a significant concentration of meta linkages, compared with the para-linked polymers, while relaxation broadness was generally greater in the dynamic mechanical mode. Changes in chemical structure had little effect on the shape, intensity, and location of the β-relaxation peak, the main observation being that the Arrhenius activation energy measured by dynamic mechanical analysis was significantly higher than that calculated from the dielectric data. The dielectric β-relaxation was sensitive to absorbed moisture. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 851–859, 1998     

Open spaces and molecular motions of polyether-based network polymers probed by positron annihilation

The lifetimes of positrons have been measured for network polymers based on polyethers. From the temperature dependence of the lifetime of ortho-positronium (o-Ps), τ₃, for the network polymer of poly(ethylene oxide-co-propylene oxide) [P(EO/PO)], an onset temperature for limited local motions of molecules, T_γ, and the glass transition temperature, T_g, were determined to be 57 and 201 K, respectively. For the network polymer of poly[EO-co-2-(2-methoxyethoxy)ethyl glycidyl ether] [P(EO/MEEGE)], T_γ and T_g were determined to be 57 and 185 K, respectively. For both specimens, above 270 K, the observed linear temperature dependence of τ₃ was attributed to the thermal expansion of open spaces in a liquid state. In the temperature range between T_γ and 270 K, for the P(EO/MEEGE) network, τ₃ was longer and its intensity was smaller than those for the P(EO/PO) network. These results were attributed to the increase in the size of open spaces for the P(EO/MEEGE) network polymer and the blocking of these regions by motions of side chains and chain ends. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 1919–1925, 1998     

Miscibility and crystallization behavior of solution-blended PEEK/PI blends

Miscibility and crystallization behavior of solution-blended poly(ether ether ketone)/polyimide (PEEK/PI) blends were investigated by using DSC, optical microscopy and SAXS methods. Two kinds of PIs, YS-30 and PEI-E, which consist of the same diamine but different dianhydrides, were used in this work. The experimental results show that blends of PEEK/YS-30 are miscible over the entire composition range, as all the blends of different compositions exhibit a single glass transition temperature. The crystallization of PEEK was hindered by YS-30 in PEEK/YS-30 blends, of which the dominant morphology is interlamellar. On the other hand, blends of PEEK/PEI-E are immiscible, and the effect of PEI-E on the crystallization behavior of PEEK is weak. The crystallinity of PEEK in the isothermally crystallized PEEK/YS-30 blend specimens decreases with the increase in PI content. But the crystallinity of PEEK in the annealed samples almost keeps unchanged and reaches its maximum value, which is more than 50%. The spherulitic texture of the blends depends on both the blend composition and the molecular structure of the PIs used. The more PI added, the more imperfect the crystalline structure of PEEK. © 1998 John Wiley & Sons, Inc. J. Polym. Sci. B Polym. Phys. 36: 2267–2274, 1998     

Electrochemical fabrication of all organic heterojunction for polythiophene and its derivatives

A new kind of all-organic heterojunction consisting of polythiophene and its derivatives was prepared by the electrochemical method in the presence of boron trifluoride diethyl ether as supporting electrolyte on indium–tin oxide glass electrode. It was observed that sequential-different oxidation potential among layers of polythiophenes is a prerequisite for the heterojunction to show rectification effect. The carrier-flow of the three semiconductors for PBrT/PT/PMT heterojunction was discussed in detail. Its rectification ratio, barrier height, and ideality factor were 392 (±2 V), 0.89 eV, and 8.1, respectively. © 1998 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 36: 2905–2910, 1998     

Micelle-like macromolecular systems for controlled release of daunomycin

Soluble macromolecular conjugates for the delivery of the strongly hydrophobic anticancer drug daunomycin (DM) or rubomycin with its controlled release were prepared. The solution properties of these conjugates consisting of DM bonded to copolymer of maleic anhydride and divinyl ether (DIVEMA) and a few model compounds were investigated using adsorbance spectroscopy, as well as surface activity and solubilization of water-insoluble dye measurements. The data of these studies indicated that in water solutions conjugates are associated, probably intramolecularly. This micellization in parallel with an H-bonded ionic complex between DM and polymer carrier determines the DM release. It is concluded that the desirable drug release can be achieved through changing the structure of conjugates by means of varying the constituents hydrophobicity. © 1998 John Wiley & Sons, Ltd.     

压缩比和CO2对二甲醚燃料均质压燃燃烧的影响

在一台2-135柴油机上实现了纯二甲醚(DME)的均质充量压燃(HCCI)的燃烧方式.为了扩展发动机适用工况,控制HCCI着火,进一步通过调节试验发动机压缩比以及在优化的压缩比下在进气道中加入气体CO2的方法来改进和控制HCCI的燃烧.试验结果表明,DME的HCCI燃烧模式不但可以实现无烟燃烧,还可以有效控制发动机NOx排放,使其接近于零排放.在试验负荷范围内,CO排放随负荷增加而降低;HC的排放随负荷增加而减少.对DME的HCCI燃烧机理等进行研究表明,由于纯DME十六烷值高导致着火较早(上止点前28°左右),该发动机只能在中低负荷较小范围内运行.改进的燃烧方法可以有效地控制HCCI燃烧,拓展HCCI发动机运转范围.     

二乙二醇十八烷基醚单甲基丙烯酸酯及其聚合物的制备和表征简

以二乙二醇十八烷基醚和甲基丙烯酰氯为原料,采用醇钠-酰氯法合成了二乙二醇十八烷基醚单甲基丙烯酸酯(DEGOEMA),并利用自由基聚合得到聚(二乙二醇十八烷基醚单甲基丙烯酸酯)(PDEGOEMA). 采用凝胶渗透色谱(GPC)分析测试了PDEGOEMA的分子量和分子量分布. 通过傅里叶变换红外光谱(FTIR)、核磁共振氢谱(1H NMR)、差示扫描量热(DSC)、热重(TG)和X射线衍射(XRD)对DEGOEMA和PDEGOEMA的结构、相变行为、热稳定性和晶体结构进行了研究. 结果表明,这种新型单体及其聚合物是一种具有稳定的结构、良好的结晶性能、高相变焓及良好热稳定性的相变材料. PDEGOEMA的起始吸热温度为41 ℃,起始放热温度为36 ℃,热焓为73 J/g,在314 ℃以下热稳定性良好,可用于加工或使用温度较高的环境.     

冠醚修饰卟啉的合成及其荧光开关性能

设计合成了一个5,15-meso-meso冠醚修饰的卟啉1（化合物1）作为荧光开关的模型化合物,选择Cu+离子作为淬灭剂,激发该化合物不同发光单元时,分别记录化合物1的荧光淬灭效果,发现不同激发光的使用可以调节激发电子的流向,同时有效地表现出Cu+离子调控下的荧光开关性能.文中对目标化合物进行了详细的表征,同时对化合物1的开关性能进行了合理的解释.     

冠醚配合物:[Na3(15-C-5)3(SCN)][Zn(NCS)4]的合成与晶体结构

研究了15冠5与Na2[Zn(SCN)4]的反应,得到了配合物[Na3(15-C-5)3(SCN)][Zn(NCS)4].通过熔点、红外光谱、元素分析、单晶X-射线衍射对该配合物进行了表征.配合物为正交晶系,空间群为P2(1)2(1)2(1),晶体学数据a=1.421(5)nm、b=1.920 4(8)nm、c=2.239 4(10)nm,α=β=γ=90°,V=5.342(4)nm3,Z=4,Dcald=1.350g/cm3,F(000)=2272,R1=0.0532,WR2=0.126 3.配合物由一个{[Na3(15-C-5)]3(SCN)}2+配阳离子和一个[Zn(NCS)4]2-配阴离子组成.在配阳离子{[Na3(15-C-5)]3(SCN)}2+中,两个Na分别与一个SCN基团S和N成键,第三个Na与SCN中C≡N基团存在Na+-π相互作用.配阴离子[Zn(SCN)4]2-与配阳离子{[Na3(15-C-5)]3(SCN)}2+通过静电相互作用形成中性配合物.