低聚离子液体的体相与界面及其电化学储能应用

近年来,随着单阳离子液体的发展,新型低聚物离子液体被合成并应用。这类离子液体可看作是由几个重复的单阳离子组合而成,可以通过改变阳离子带电基团、间隔连接的长度或种类、末端链的长度以及阴离子种类来获得更多不同的结构。因此,低聚离子液体有更复杂的微观结构和内部相互作用,决定了其多特征的物化性质和电化学特性,有望满足更多对溶剂性能有特定要求的应用。例如,与单阳离子液体相比,低聚离子液体具有更大的可调节性、更宽的液态温度范围、更高的热稳定性等优点,使其在电化学储能设备中得到越来越多的应用,如用作超级电容器和锂离子电池的电解液。在本综述中,我们系统地总结并详细解释了低聚离子液体的性质和结构（包括单个离子的结构和本体液内部的纳米组织）之间的关联,主要是双阳离子液体和三阳离子液体;概括了低聚离子液体作为超级电容器和锂离子电池的电解液的相关研究,重点阐述了由低聚离子液体和不同类型电极组成的双电层的结构和性能,以及与相应单阳离子液体电解液的比较结果;提供了降低低聚离子液体粘度和加速离子扩散的优化措施,提出了低聚离子液体电解液未来可能面临的主要问题和发展前景。     

Circular dichroism induced by Fano resonances in planar chiral oligomers

We present a general theory of circular dichroism in planar chiral nanostructures with rotational symmetry. It is demonstrated, analytically, that the handedness of the incident field's polarization can control whether a nanostructure induces either absorption or scattering losses, even when the total optical loss (extinction) is polarization‐independent. We show that this effect is a consequence of modal interference so that strong circular dichroism in absorption and scattering can be engineered by combining Fano resonances with planar chiral nanoparticle clusters.

     

Preparative isolation and purification of antioxidative stilbene oligomers from Vitis chunganeniss using high‐speed counter‐current chromatography in stepwise elution mode

Preparative high‐speed counter‐current chromatography (HSCCC) was successfully applied to the isolation and purification of three stilbene oligomers from Vitis chunganeniss using stepwise elution with a pair of two‐phase solvent systems composed of n‐hexane–ethyl acetate–methanol–water at (2:5:2:5, v/v) and (1:2:1:2, v/v). The preparative HSCCC separation was performed on 800 mg of crude sample yielding hopeaphenol (21.1 mg), amurensin G (37.2 mg) and vitisin A (95.6 mg) in a one‐step separation, with purities over 95% as determined by HPLC. The structures of these three compounds were identified by MS, ¹H NMR and ¹³C NMR. In addition, their antioxidant activities were screened by DPPH assay, where vitisin A showed strong antioxidant activity. Further EPR experiments with spin‐trapping technique demonstrated that vitisin A is a potent and selective singlet oxygen quencher, which may be used in singlet oxygen‐mediated diseases as a pharmacological agent.     

聚苯乙烯齐聚物的高效尺寸排除色谱的研究——Ⅱ.折光指数增量的分子量依赖性

对齐聚物中各半分散组分的折光指数增量、尺寸排除色谱响应面积与重量分数之间的相互关系作了数学分析。折光指数增量的分子量依赖性完全起源于端基效应。提出了一个对高分子的尺寸排除色谱谱图,作折光指数增量改正的理论方程,其中包含端基与结构重复单元的分子量以及两者折光指数增量的比值,此比值可事先用Lorenz-Lorentz或Gladstone-Dale方程计算得到。理论的推断从苯乙烯齐聚物的HPSEC实验数据得到了证实。     

Preparation of fluoroalkyl end-capped cooligomers/silica nanoparticles: A new approach to fluorinated nanoparticle inhibitors of Human Immunodeficiency Virus Type 1 and Simian Immunodeficiency Virus (SIVmac)

Fluoroalkyl end-capped acrylic acid and sulfonic acid cooligomers reacted with tetraethoxysilane (TEOS) and silica/nanoparticles under alkaline conditions to afford the corresponding cooligomers/silica nanoparticles (mean diameters: 32-173 nm) with a good dispersibility and stability in aqueous and organic media. Interestingly, fluorinated nanoparticles containing carboxy groups were found to exhibit a potent and selective anti-HIV-1 activity in vitro. In contrast, fluorinated cooligomers containing sulfo groups were shown to have a potent and selective anti-SIV_mac activity in vitro.     

STUDY ON PET-PA66 COPOLYMER

In this work the PET-PA 66 copolymers are obtained. The characterization of chemical structure of copolymer chain by NMR method is also given. It is shown that when the 66 Nylon salt is added in the copolycondensation, the adipic acid and hexamethylenediamine reacted mainly by itself and the obtained copolymer is a random copolymer, and when the Nylon 66 oligomer is added, the obtained copolymer is a block copolymer. The result of NMR analysis is demonstrated by properties investigation.     

聚烯烃低聚物转化为双端正离子活性链及其遥爪三嵌段物的合成

非“活性”的端羧聚丁二烯及端羧聚丁腈胶通过THF开环聚合转变为双端正离子活性链。用液氨或二乙胺终止反应制得伯胺或叔胺端基遥爪聚丁二醇-聚烯烃-聚丁二醇三嵌段低聚物。     

Soluble tin(II) macroinitiator adducts for the controlled ring‐opening polymerization of lactones and cyclic carbonates

Polyesters and poly(ester carbonates) were synthesized via ring‐opening polymerization with new tin(II) macroinitiator adducts containing oligomeric L ‐lactide (LLA), rac‐lactide (rac‐LA), and ?‐caprolactone (CL). The novel initiating species were synthesized by the reaction of LLA, rac‐LA, or CL with Sn(OEt)₂ (monomer concentration/initiator concentration ≤20) and then were dissolved in methylene chloride or toluene and stored in a stoppered flask for the subsequent ring‐opening polymerization of cyclic esters and carbonates. The soluble tin alkoxide macroinitiators yielded predictable and quantitative initiation of polymerization for up to 1 month of storage time at room temperature. The resulting polymers displayed low polydispersity (≤1.5), and a high monomer conversion (>95%) was obtained within relatively short polymerization times (≤2 h). Adjusting the monomer/macroinitiator ratio effectively controlled the molecular weights of the polymers. NMR was used to characterize the initiating species and polymer microstructure, and size exclusion chromatography was used to determine the molecular weight properties of the polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3434–3442, 2002     

Linear all-ortho oligomers of phenol–formaldehyde resins. I. Preparations,characterizations, and solution properties

Three kinds of all-ortho methylene-linked phenolic oligomers, i.e., 4-tert-butylphenol (BP), phenol (AO), and O-methylated BP (BPM), were prepared with good yields and their dilute solution properties were studied. In acetone, all of these oligomers are highly solvated and molecularly dispersed. In chloroform, however, AO and BP molecules strongly form hydrogen bonds among themselves. By intramolecular and intermolecular hydrogen-bondings, a large portion of the dimers and the trimers of AO and BP associate to form bimolecular aggregates in chloroform, assuming pseudo-cyclic conformations analogous to calix [4] arene and calix [6] arene, respectively. By intramolecular hydrogen-bonding, the tetramers and the hexamers also form pseudo-cyclic conformations by themselves in chloroform. © 1993 John Wiley & Sons, Inc.     

Determination of the structural arrangements of ketene oligomers using NMR, FT-IR and ESI-MS

Oligomer of ketene was synthesized using glycine as the source material in presence of free electron rich carbon through free radical mechanism. The structure and the compositions were determined by using ¹³C{¹H} NMR and DEPT – 135 spectroscopy measurements. Two-dimensional heteronuclear (HETCOR) NMR spectroscopy was used to resolve the ¹H NMR spectrum of the polymer. The NMR spectra reveal that the oligomers were generated as oligoester (OE), oligoketene (OK) and oligoacetal (OA) structural units. ESI-MS and ATR-FTIR also support these types of structural units in the crude polymer.