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991.
992.
The reaction of 7‐mercapto‐4‐methylcoumarin (4) with 1‐mono‐ and 1,1‐dimethyl propargyl alcohols in H3PO4 afforded the corresponding β‐(7‐coumarinthio)ketones with a rearrangement of the carbon chain of propargyl. A possible mechanism of this rearrangement was proposed. 相似文献
993.
994.
Jianxin Mu Guibin Wang Chunling Zhang Xiujie Li V. V. Kireev 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9):742-747
A series of hyperbranched poly(ether ether ketones) with different chain length between branching point (L) were prepared using a A2+B3 methodology, in which the A2 is hydroxyl‐terminated PEEK oligomer. The L affects the properties of the polymers such as the inherent viscosity, the degree of crystallinity, the thermal properties of the polymers etc. The polymer with a L2≈8 had T g (122.4°C), T c (200.2°C), and broad T m (247.4°C). With the increment of L, up to the point L2≈20 and L2≈35, the polymers become semi‐crystalline, with a melting point of 300.9°C and 317.9°C, respectively. Their wide angle X‐ray scattering (WAXS) pattern indicated that their crystal structure is exactly the same as that of the linear homopolymer. 相似文献
995.
New fluorinated aromatic poly (ether ketone amide)s containing cardo structures were prepared by a heterogeneous palladium‐catalyzed polycondensation of fluorinated aromatic diiodides with ether ketone units, aromatic diamines containing cardo groups, and CO. Polymerizations were conducted in N,N‐dimethylacetamide at 120°C using 6 mol% of magnetic nanoparticles‐supported bidentate phosphine palladium (II) complex [Fe3O4@SiO2‐2P‐PdCl2] as catalyst and 1,8‐diazabicyclo[5,4,0]‐7‐undecene as base and resulted in fluorinated cardo poly (ether ketone amide)s with inherent viscosities up to 0.75 dL/g. All the polymers were readily soluble in many organic solvents and could afford transparent, flexible, and strong films by solution casting. These polymers showed good thermal stability with the glass transition temperature of 237°C–258°C, the temperature at 5% weight loss of 462°C–477°C in nitrogen. These polymer films also exhibited good mechanical properties, excellent electrical and dielectric performance, and high optical transparency. The incorporation of bulky fluorinated groups and cardo structures into polymer backbone has played an important role in the improvement of solubility, dielectric performance, and optical properties. Importantly, the heterogeneous palladium catalyst can easily be recovered from the reaction mixture by simply applying an external magnet and recycled up to 7 times without significant loss of catalytic activity. 相似文献
996.
通过溶液流延法制备了磺化聚醚醚酮/锂皂石(SPEEK/Lap)复合膜, 对其物理化学性质、 机械性能、 化学稳定性及单电池性能进行了测试. 在SPEEK基质中引入的Lap有效改善了复合膜的质子传导率、 溶胀率和机械性能. 当Lap添加量(质量分数)从0.2%增到1.5%时, 复合膜的质子传导率随之增加(19.9~23.6 mS/cm). SPEEK/Lap-0.2复合膜的自放电时间为57.2 h, 是Nafion 117膜的2.4倍和纯SPEEK膜的1.5倍. 在80 mA/cm 2电流密度下, SPEEK/Lap-0.2复合膜的电压效率(VE, 86.5%)和能量效率(EE, 84.0%)明显高于Nafion 117膜(VE: 83.8%, EE: 80.7%)和纯SPEEK膜(VE: 81.4%, EE: 78.9%). 同时, SPEEK/Lap-0.2复合膜经100次充放电循环测试后具有良好的循环稳定性和结构稳定性. 相似文献
997.
由3,3′-双(4-羟基苯基)苯并吡咯酮(HPP)和4,4′-二氟二苯酮经亲核缩聚合成聚芳醚酮(PEK-H),再经与环氧氯丙烷(ECH)的亲核取代反应,制得了一种含量可控的环氧侧基酚酞聚芳醚酮(PEK-HE)。 改变ECH的投料量,可调控环氧侧基在聚合物中的含量。 采用FTIR、1H NMR和TGA等技术对聚合物进行了结构表征与性能测试,并考察了经自固化后聚合物涂膜的性能。 涂膜热稳定性较固化前明显提高,5%热失重温度均在450 ℃以上。 涂膜具有优异的热性能和机械性能:耐温(350±20) ℃;冲击强度高于100 kg·cm。 相似文献
998.
Soufiane Touil Mohamed Taieb Ben Dhia Hedi Zantour Belgacem Baccar 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):295-302
Abstract The Lawesson reagent (L.R) reacts with phenylhydrazones of ketones γ-disubstituted phosphonates and phosphine oxide 1 to give 1,2,3-diazaphospholine derivatives 2 and 2′. Two diastereomers were obtained in some cases. The structure of the products 2 and 2′ is confirmed by NMR and IR spectroscopy. 相似文献
999.
Abstract An efficient one-step synthesis of branched functionalized benzenoid compounds from aryl methyl ketones mediated by SOCl2/EtOH is described; some novel C 3-symmetrical molecules were prepared with satisfactory yields. The method enjoys short reaction time and simple operation, and avoids use of organometallic reagents. 相似文献
1000.
Zheng Zhou Shuling Zhang Jianxin Mu Xigui Yue Zhenghua Jiang Guibin Wang 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(7):571-577
Two types of antioxidants (a phenolic antioxidant and a phosphorous antioxidant) were used to improve the stability of poly (ether ether ketone) (PEEK). To evaluate the effect of the antioxidants on the properties of PEEK and the stabilization mechanism, some characterization methods were carried out, such as rheometer, TGA, and electron spin resonance (ESR). The results indicated that the efficiency of the phosphorous antioxidant (DS) in improving the stability of PEEK was better than that of the phenolic antioxidant (DN) and the thermal stability of PEEK sample containing 0.07 wt% DS was the best among all samples due to the decrease of the free radicals density, as proven by ESR measurement. The possible stabilization mechanism of the antioxidants to PEEK was proposed to reveal the reason that caused the different performances of the two types of antioxidants to PEEK. 相似文献