含有二色性染料的PDLC的光电性能

用聚合分相法,在Ｅ－７液晶中掺入二色性液晶分散蓝,制成聚合物分散液晶膜。测定了它的光电性能。与不加二色性染料的聚合物分散液晶膜比较,膜对比度提高,响应时间τｏｎ保持不变,松驰时间τｏｆｆ略有增加。     

聚合物分散液晶膜

聚合物分散液晶膜是将液晶和聚合物结合,得到的一种综合性能优异的膜材料,液晶分子赋予了聚合物分散液晶膜显著的电光特性,使其受到了广泛的研究,并有着广阔的应用前景。而聚合物作为成膜材料,起着辅助但是重要的作用,其结构和固化过程是影响聚合物分散液晶膜电光特性的重要因素。本文简要综述了聚合物分散液晶膜的制备方法、电光特性的影响因素及研究手段。     

环氧树脂基PDLC膜的制备及其电光性能研究

将双酚Ａ环氧树脂、环氧氯丙烷和低分子量聚酰胺和Ｍｅｒｋ－Ｅ７液晶按不同比例混合，加热固化后制得聚合物分散液晶膜。研究不同配比制成的树脂基的折光度，使之与Ｍｅｒｋ－Ｅ７液晶相匹配。进一步调节聚合物与液晶的百分比，得到对比度很高的聚合物分散液晶显示材料。并对该材料作电光性能测试，以三维图形说明该材料的对比度对电压和温度和依赖性，并用实验证实了折光率与对比度成４次指数关系。     

聚合物稳定液晶材料研究进展

聚合物稳定液晶材料在显示传感、温度调控、智能材料等方面表现出优异性能,成为液晶材料领域的研究热点.针对向列相液晶、胆甾相液晶、铁电相液晶、蓝相液晶和其他相态液晶,分别介绍了聚合物网络在不同相态液晶中的作用,阐述了不同聚合物稳定液晶材料的特点及光学性能,综述了聚合物稳定液晶材料的研究进展,并指出了聚合物稳定液晶材料面临的...     

烯烃易位聚合研究新进展 在合成嵌段共聚物及功能高分子上的应用

本文详述了利用环烯烃开环易位聚合合成，ＡＢ，ＡＢＡ和星形嵌段共聚物，接枝共聚物，氧化还原性聚合物，侧链液晶高分子，导电高分子及含金属纳米聚合物材料，并对其具体合成线路作了概述。     

聚吡咯/聚合物固体电解质双层复合膜研究

在聚合物固体电解质（聚乙二醇不饱和聚酯网络－LiClO4)中进行吡咯聚合原位制得了聚吡咯／聚合物固体电解质双层复合膜。用扫描电镜观察复合膜的界面结构,用循环伏安和交流阻抗法研究了复合膜的电化学杂脱掺杂性能。结果表明,聚吡咯／聚合物固体电解质双层复合膜具有相互穿插渗透的固／固密接界面结构,这种界面结构改善了聚吡咯和聚俣物固体电解质间的界面接触,提高了聚吡咯在聚俣物固体电解质中的电化学掺杂脱掺杂性能。     

具有宽波反射特性的胆甾相液晶固体薄膜材料的研究

采用两步聚合法得到了具有宽波反射特性的固体胆甾相液晶薄膜,首先通过聚合物稳定胆甾相液晶制备了螺旋结构的高分子网络,然后灌入具有不同螺距的可聚合的胆甾相小分子液晶单体混合物,经紫外光照射聚合后获得了能够反射可见光区(450～780 nm)覆盖红蓝绿三色光的胆甾相液晶固体薄膜.扫描电镜测试结果表明,胆甾相液晶固体薄膜的断面...     

聚合物 分散液晶体系的相分离结构对温度依赖性的研究

在不同温度下采用紫外光引发相分离法制备了聚合物分散液晶样品．用光学显微镜及扫描电镜研究了样品的相分离结构．采用对样品施加电压观察其微结构轮廓，或测量液晶微粒相变点的简单方法研究了聚合温度对相分离结果的影响．结果表明，在一定温度范围内，随着温度的增高，液晶微粒的平均尺寸趋于减小，而且形成的液晶微粒也逐渐变纯．作者给出了这些测试结果并进行了讨论．     

《液晶高分子材料》专辑序言——老学科的新活力

正19世纪80年代后期,奥地利植物学家Reinitzer和德国物理学家Lehmann共同发现了液晶,创立了液晶科学。20世纪70年代,液晶显示技术实现了革命性突破,风靡全球。液晶高分子的研究始于1937年的生物高分子液晶,随即受到广泛关注,尤其是杜邦公司基于溶致液晶芳香族聚酰胺的液晶纺丝技术在1972年推出的Kevlar系列高性能纤维产品,极大地推动了液晶高分子的飞速发展。近几十年来,基于热致液晶芳香族聚酯的高性能工程塑料如雨后春笋般不断涌现,高性能液晶高分子结构材料也成为全球研究热点。同时,侧链高分子液晶、聚合物分散液晶、聚合物稳定液晶、全息聚合物分散液晶以及新型结构的高分子液晶、超分子液晶在显示、传感、防伪、数据存储和电子封装等领域的应用也成为高性能液晶高分子功能材料的研究亮点。其中让我们倍感骄傲的是,我国科学家周其凤院士于1987年设计、合成了甲壳型液晶高分子,为液晶高分子科学与材料的发展做出了原创性贡献。当前,液晶材料的高分子化、高分子材料的液晶化已成为化学、材料、光学工程和信息工程等相关学科的重要研究方向,尤其近期在光存储、5G通讯领域中的应用备受关注。     

丙烯酸酯/液晶体系的光聚合反应动力学对PDLC电光性质的影响

采用光-示差扫描量热法(P-DSC)和光-流变学(P-Rheology)技术,测定了丙烯酸酯/液晶体系的光聚合反应动力学和凝胶化时间.基于自催化模型和凝胶时间-温度关系,计算了体系的光聚合反应速率常数和活化能,探讨了单体结构与组成、反应温度对体系光聚合动力学的影响,并研究了聚合物分散液晶(PDLC)的电光响应行为与相分离结构对光聚合动力学的依赖性.结果表明,升高反应温度、增加体系的单体反应活性和平均官能度,均提高了体系的光聚合速率常数,缩短了光聚合凝胶时间.随着单体反应活性和平均官能度的提高,体系的光聚合反应活化能明显降低,且凝胶化前的光聚合反应活化能低于光聚合全过程的平均反应活化能.当液晶含量为50%时,形成的PDLC呈亚微米尺度的双连续相结构.随着光聚合反应温度的升高,光聚合速率加快,导致凝胶时间缩短、相分离程度降低,使PDLC中液晶相尺寸变小、聚合物网络致密化,PDLC的弛豫时间延长、饱和电压降低,而开启时间和阈值电压变化不大.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

Toward new camptothecins. Part 6: Synthesis of crucial ketones and their use in Friedländer reaction

In the context of the preparation of camptothecin and luotonin A analogs, the synthesis of some key keto-precursors and their use in Friedländer condensation are described. This paper also focuses on the stability of these keto intermediates and emphasizes the major differences between indolizinones and pyrroloquinazolinones series. Noteworthy is also the report of some original structures isolated as by-products of some experiments.     

CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

Highly regioselective Buchwald–Hartwig amination at C-2 of 2,4-dichloropyridine enabling a novel approach to 2,4-bisanilinopyridine (BAPyd) libraries

The highly regioselective Buchwald–Hartwig amination at C-2 of the cheap and readily accessible reagent, 2,4-dichloropyridine with a range of anilines and heterocyclic amines is described. This new methodology is robust and provides a facile access to 4-chloro-N-phenylpyridin-2-amines on 0.25 mol scale. These intermediates undergo a further Buchwald–Hartwig amination at higher temperature to enable rapid exploration of the chemical space at C-4 and to provide a library of 2,4-bisaminopyridines.     

KMnO4-mediated oxidative CN bond cleavage of tertiary amines: Synthesis of amides and sulfonamides

KMnO₄-mediated oxidative CN bond cleavage of tertiary amines producing secondary amine was introduced, which was trapped by electrophiles (acyl chloride and sulfonyl chloride) to form amides and sulfonamides. The reaction could take place at mild condition, tolerating a wide range of function groups and affording products in moderate to excellent yields.     

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

The review contains a concise historical account and information on the most significant researches undertaken by the staff at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences on the Chemistry of Heterocyclic Compounds. Dedicated to Academician of the Russian Academy of Sciences B. A. Trofimov on his 70th jubilee. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1443–1502, October, 2008.     

Sulfur-directed metal-free and regiospecific methyl C(sp3)–H imidation of thioanisoles

Regiospecific and direct imidation of the methyl C(sp³)–H bond of thioanisoles is realized under mild and metal-free conditions with N-fluorobis(benzenesulfonyl)imide as an oxidant and nitrogen source. Proposed mechanism suggests that thionium ion intermediates and a Pummerer-type reaction are involved. The imidation has advantages such as high step-economy, excellent functionality tolerance, and regiospecificity, giving structurally diverse imidation products.     

Selective syntheses of 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones via temperature-dependent Rh(II)-carbenoid-mediated 2H-azirine-ring expansion

The Rh(II)-catalyzed reaction of 2-carbonyl-substituted 2H-azirines with ethyl 2-cyano-2-diazoacetate or 2-diazo-3,3,3-trifluoropropionate provides an easy access to 2H-1,3-oxazines and 1H-pyrrol-3(2H)-ones. These compounds can be selectively prepared from the same starting material using temperature as the only varied parameter. The 2-azabuta-1,3-diene intermediate, a common precursor for both heterocyclic products, isomerizes into 2H-1,3-oxazine under kinetic control, while 1H-pyrrol-3(2H)-one is the sole product of the reaction at elevated temperatures. According to DFT-calculations a one-atom oxazine ring contraction involving ring-opening to a 2-azabuta-1,3-diene intermediate, followed by a 1,5- and 1,2-prototropic shift leads to the consecutive formation of imidoylketene and azomethine ylide, which then further undergo cyclization to the pyrrole derivative.     

Synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives

Different approaches for the synthesis of 1-benzyloxypyrazin-2(1H)-one derivatives from simple amino acids have been investigated. A library of 33 precursors for the preparation of N-hydroxy pyrazinones was obtained in moderate to good yields.