The Research Progress of Polymer/Graphene Nanocomposites

石墨烯以其优异的力学、光学、电学和热学性能,得到日益广泛的关注和研究。本文介绍了石墨烯的结构、性能和特点,并对石墨烯的改性方法进行了概括。本文着重综述了高分子／石墨烯纳米复合材料的研究现状和进展,并介绍了高分子／石墨烯纳米复合材料的三种制备方法,即原位插层聚合法、溶液插层法和熔融插层法。此外,还对高分子／石墨烯纳米复合材料的应用前景进行了展望,并对石墨烯复合材料研究存在的问题和未来的研究方向进行了讨论。     

石墨烯/高分子复合薄膜的制备及应用

石墨烯是一种单原子厚度的二维碳纳米材料,具有优异的光、电、热和力学性能,以及巨大的比表面积.石墨烯与高分子之间能够通过共价或非共价作用(氢键、π-π作用、静电作用等)进行复合.这些相互作用既增加了石墨烯在高分子中的溶解性或分散性,也可以提高复合材料的性能或拓展其功能.目前常用的制备石墨烯高分子复合材料的方法有溶液混合、熔融共混和原位聚合等.该类复合材料可以通过蒸发溶剂、溶液涂覆、真空抽滤、层层自组装等途径加工成相应的复合膜.石墨烯高分子复合薄膜在制备高强度结构材料、超级电容器、光伏器件、锂离子电池负极材料以及传感器等方面具有重要的应用价值.本文综述了近年来石墨烯高分子复合薄膜的制备和应用方面的研究进展,并对该领域进行了展望.     

石墨烯复合材料在锂离子电池中的研究进展

石墨烯复合材料因其独特的结构和优异的性质被认为是最有潜力的锂离子电池负极材料之一.石墨烯基复合材料是解决充放电过程中的电极体积变化导致电池的循环性能变差这一问题的有效途径.本文作者综述了多种石墨烯基复合材料作为锂离子电池负极时的电化学性能,并展望了未来的研究方向.     

石墨烯改性树脂基复合材料力学性能研究进展

树脂基复合材料具有比强度高、比模量大、耐高温、耐腐蚀、质轻等诸多优点,在航天军工、生物医疗、电子封装、体育器材等众多领域得到广泛应用。石墨烯作为一种典型的二维纳米材料,凭借其独特结构以及优异的物理化学性能而备受关注。近年来的研究表明石墨烯可以通过对增强纤维改性和对基体树脂改性的方法来提高树脂基复合材料的力学性能。本文介绍了石墨烯改性树脂基复合材料的增强增韧机理,对石墨烯改性纤维(碳纤维、玻璃纤维、芳纶纤维)增强复合材料以及树脂的改性方法进行了综述;着重阐述了石墨烯改性树脂基复合材料力学性能的研究进展,分析了石墨烯改性树脂基复合材料研究中依旧存在的两大问题,即石墨烯的分散性和界面结合问题,并对石墨烯改性树脂基复合材料的未来发展前景进行了展望。     

石墨烯及其聚合物纳米复合材料

石墨烯是一种新型的二维纳米碳材料,具有优异的机械性能、电性能和热性能等,是聚合物纳米复合材料的理想填料。近年来,石墨烯/聚合物纳米复合材料成为聚合物基纳米复合材料的研究热点。本文对石墨烯及其聚合物纳米复合材料的研究进展进行了综述。首先概述了石墨烯的不同制备方法及石墨烯的共价与非共价改性途径。然后重点总结了石墨烯/聚合物纳米复合材料的常用制备方法及其机械性能、导电性、导热性、耐热性及阻隔性能。最后,对该领域所存在的问题进行了总结,并展望了其发展趋势。     

石墨烯基光学复合材料及其光学应用

石墨烯是近年来发现的一种新型二维晶体碳材料,由单层碳原子构成,具有规则六方对称的蜂巢结构,使其表现出优异的力学、电学和光学性能,近年来迅速成为材料学及光电化学等领域研究热点。本文综述了石墨烯基光学复合材料及其光学应用的研究进展,展望了石墨烯基光复合材料的光学应用前景及发展方向。     

电化学法绿色快捷制备石墨烯及其复合材料

石墨烯及其复合材料具有优异的物理和化学性能,在电子、能源、催化、医药以及生物传感等领域应用潜能巨大,因此探究高质量、高产量和规模化的制备方法对石墨烯基复合材料未来的开发和应用至关重要.电化学法是一种有望实现绿色规模化制备石墨烯及其复合材料的方法,本文作者综述了国内外电化学制备石墨烯及其复合材料的主要方法:阳极氧化、阴极还原、电化学还原、离子液体功能化、电沉积、电聚合等,并对其反应原理和主要影响因素进行了详细的分析和介绍,最后对其应用前景进行了深度的展望.     

石墨烯用于金属腐蚀防护的研究

单层无缺陷石墨烯具有优异的屏蔽性能,能阻隔氧气、水分子等腐蚀因子到达金属基体表面,被认为是已知最薄的腐蚀防护涂层。基于石墨烯在金属腐蚀防护领域巨大的应用潜力,本文从石墨烯薄膜防护涂层、石墨烯/有机防护涂层以及石墨烯-导电高分子/有机防护涂层等方面进行系统总结,重点围绕石墨烯薄膜存在的问题以及石墨烯在有机涂层中均匀分散等进行详细分析和介绍,同时对石墨烯基防腐涂料的未来发展进行了展望。     

石墨烯/橡胶纳米复合材料

石墨烯具有极高的力学性质和导电/导热性质,在橡胶复合材料中具有广阔的应用前景.本文首先简要综述了石墨烯的制备和功能化,而后重点介绍了石墨烯/橡胶复合材料的制备方法、性能及相关的结构-性能关系研究的现状,并对石墨烯/橡胶复合材料研究的挑战和机遇进行了展望.     

参杂缺陷石墨烯的高分子复合材料导热特性分子动力学模拟（英文）

传统高分子材料由于内部分子链无规则缠绕的特点,导致其热导率较小。近年来,拥有高导热特性的新型高分子材料在众多领域都显示出了极大的发展潜力。随着研究的不断深入,具有优秀导热能力的石墨烯等低维碳材料引起越来越多人的关注。引入石墨烯制作的高分子复合材料具有较高的导热性能,在热管理方面具有很大的应用前景。本文使用非平衡态分子动力学方法计算了石墨烯点缺陷对石墨烯-高分子复合材料界面热导和整体热导率的影响。石墨烯层的界面热导受点缺陷密度的影响较大。当石墨烯缺陷密度由0%增大到20%时,其界面热导由75.6 MW·m~(-2)·K~(-1)增加为85.9 MW·m~(-2)·K~(-1)。石墨烯点缺陷造成sp~2共价键断裂、结构刚性下降,导致其振动态密度的低频分量增加,增强了与高分子基质间的低频能量耦合,进而提高了界面热导。而点缺陷密度的增大对复合材料整体热导率也具有相似的提升效果(从40.8 MW·m~(-2)·K~(-1)增加为45.6 MW·m~(-2)·K~(-1))。此外,高分子基体在石墨烯界面处会造成局部密度提高,但石墨烯点缺陷对高分子材料局部密度提升并无显著影响。这些计算结果加深了对石墨烯与高分子基体间导热机理的理解,并有助于开发和设计具有优异热学性能的高分子复合材料。     

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.