聚丙烯酸/SiO2杂化纤维的制备与表征

采用溶胶凝胶-原位聚合法以正硅酸乙酯(TEOS)为硅源、乙烯基三乙氧基硅烷(VTEOS)为偶联剂制备了活性SiO2溶胶,经水解、缩合,再于引发剂AIBN作用下与丙烯酸进行原位聚合杂化,制得聚丙烯酸/SiO2杂化溶胶,陈化后用拉丝法制得聚丙烯酸/SiO2杂化纤维。研究了溶胶的杂化机理、成纤性能;采用红外光谱、扫描电子显微镜分析了杂化纤维的结构和微观形态;进行了杂化纤维的TGA和耐水性能测试。结果表明,该聚丙烯酸/SiO2杂化溶胶拉丝性能好,可拉丝时间达1h,杂化溶胶在粘度为1400～3000mPa.s时成纤性能好,可通过拉丝法制得形态良好的杂化纤维;聚丙烯酸与SiO2之间通过化学键作用,在纤维内部有机无机两相间形成均一的连续相;聚丙烯酸/SiO2杂化纤维的耐热和耐水性能均优于纯PAA。     

非共价键合杂化体系中聚己内酯的非等温结晶动力学

非共价键合杂化体系中聚己内酯的非等温结晶动力学;聚己内酯;有机-无机杂化材料;差示扫描量热法;非等温结晶动力学     

有机-无机杂化分离膜研究进展

有机-无机杂化膜材料结合了有机膜材料和无机膜材料的优良性能,已成为分离膜材料研究的一个热点。本文以有机、无机组分间相互作用类型对其进行分类,着重介绍组分间以化学键相结合的有机-无机杂化膜的优良特性,总结了影响此类杂化膜结构和性能的主要因素,概括了它在膜分离中的应用,提出了目前研究工作中存在的不足,并做出了简要的述评。     

溶胶-凝胶法制备光固化聚氨酯丙烯酸酯杂化材料的研究

以溶胶-凝肢法制备的硅溶胶为无机相,聚氨酯丙烯酸酯为有机相,以γ-甲基丙烽酰氧丙基三甲氧基硅烷(TMSPM)为两相间的偶联剂,制得了光固化杂化材料。研究了未固化的杂化体系的稳定性问题,并对其进行了结构表征和性能研究。无机相与有机相通过共价键相连。使得杂化体系光固化膜高硬度的获得并没有以柔韧性的损失为代价。在无机物含量较低时,聚氨酯丙烯酸酯／二氧化硅杂化体系先固化膜的耐磨性略有提高。     

巯基-内酰胺引发活性自由基接枝聚合制备凹凸棒土/聚苯乙烯杂化粒子的研究

通过γ-巯丙基三甲氧基硅烷(MTS)与凹凸棒土(ATP)表面上的羟基发生脱醇反应,制得表面巯基化的改性粒子ATP-MTS;基于“引发剂转移终止剂”(iniferter)原理,构建巯基-己内酰胺(thiol-caprolactam)双组份引发剂转移终止体系引发苯乙烯活性自由基接枝聚合,制得表面接枝聚苯乙烯的杂化粒子ATP-g-PS.通过红外光谱(FTIR)、X射线光电子能谱(XPS)、热失重分析(TGA)、高分辨率透射电镜(TEM)等方法对杂化粒子ATP-g-PS的结构、组成、形貌进行了表征.结果表明,巯基-己内酰胺双组份引发剂转移终止体系可有效实现苯乙烯的活性接枝聚合,聚苯乙烯成功接枝到改性粒子ATP-MTS表面;模拟实验表明聚合体系呈现活性聚合的特征,单体转化率和PS的分子量均随反应时间的增加而增大,TGA结果表明制得的杂化粒子表面PS接枝率为33.3％.     

溶胶-凝胶法制备光学杂化功能材料

在简述溶胶-凝胶法基本原理的基础上,介绍了设计杂化材料的原则及预掺杂法、后掺杂法和原位化学合成法三种溶胶-凝胶法制备光学杂化功能材料的途径;综述了稀土发光材料、波导材料和光致变色材料三种光学杂化功能材料,并结合国内外的研究提出开展光学杂化功能材料研究的重要方向.     

有机-硅胶杂化整体柱的制备及应用研究进展

有机-硅胶杂化整体柱结合了有机聚合物整体柱和硅胶整体柱的优势, 具有制备简单、机械强度高和通透性好等优点, 近年来备受关注. 有机-硅胶杂化整体柱的制备方法主要有常规溶胶-凝胶法、“一锅法”和其它聚合方法. 目前, 杂化整体柱已被广泛应用于微纳尺度分离分析、样品预处理和固定化酶反应器基质中. 本文综述了有机-硅胶杂化整体柱的制备方法及应用研究进展, 并展望了其今后的发展前景.     

含倍半硅氧烷的杂化聚合物

从杂化材料的形成方式 ,说明含倍半硅氧烷类杂化材料是基于化学键合作用形成的分子内杂化体系 ,是一类新型高性能的有机_无机杂化材料。介绍了倍半硅氧烷的结构、合成方法及性能特点 ,重点阐述了多面齐聚倍半硅氧烷类杂化聚合物的性能特点及其发展趋势。     

全氟磺酸树脂/二氧化钛杂化薄膜的制备与表征

利用可溶性全氟磺酸树脂和二氧化钛前躯体钛酸丁酯液-液相体系, 结合蒸汽水热结晶方法制备了全氟磺酸树脂/二氧化钛杂化薄膜, 并通过扫描电子显微镜(SEM)、X-射线衍射(XRD)、红外光谱分析仪(FT-IR)及紫外-可见分光光度计(UV-vis)等测试方法对杂化薄膜的形貌、晶型、结构及光学性能进行了表征. 结果表明: 蒸汽水热结晶法能促进全氟磺酸树脂/二氧化钛杂化薄膜的结晶和相变; 水热后该杂化薄膜表面平整光滑, 没有裂纹, 二氧化钛晶型为锐钛矿并以球形微粒均匀分散在全氟磺酸树脂基体中; 随着杂化体系中二氧化钛含量的增多, 其粒径逐渐减小、团聚现象消失且杂化薄膜的紫外吸收性能显著提高.     

溶胶-凝胶法制备二氧化钛纳米粒子及在光固化体系中的稳定分散

选用3种不同的稳定剂,乙酰丙酮(acac),异丙氧基三(焦磷酸二辛酯)钛(TTPO)和可聚合有机磷酸酯(MAP),采用钛酸四正丁酯(TBT)通过溶胶-凝胶法合成了一系列二氧化钛溶胶,并与树脂/单体相混合,制备成有机-无机杂化光固化涂料.利用FT-IR监测了TBT水解缩合形成溶胶的过程及杂化体系的光聚合过程.杂化固化膜SEM结果显示,在合成溶胶过程中添加不同的稳定剂对杂化固化膜中无机粒子粒径尺寸等形态有显著影响,其中使用TTPO作为稳定剂得到的无机粒子分散最均匀,粒径最小,约20 nm.物理性能测试表明光固化杂化膜在硬度和柔韧性方面都有明显的改善.     

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.