嵌段共聚物自组装的研究进展

嵌段共聚物自组装在光学、电子、信息、化学及生物领域有着广泛的应用前景.本文从实验观测、理论研究和计算机模拟三个方面概述了嵌段共聚物自组装领域的研究进展.在实验观测方面,着重介绍了嵌段共聚物在体相及膜中的自组装及外场调控作用方面的研究进展;理论方面则分别介绍了强分相理论、弱分相理论、自洽场理论、动态密度泛函方法和元胞动力学等在嵌段共聚物自组装领域的应用;计算机模拟方面就 Monte Carlo 模拟、耗散粒子动力学等方法在该领域的应用作了详细的阐述.     

嵌段共聚物调控纳米粒子自组装的研究进展

嵌段共聚物和纳米粒子复合纳米材料具有优异的性能,在生物医药、光电材料、催化材料等领域具有很大的应用价值,已成为备受关注的研究热点.利用嵌段共聚物自组装能够形成特定形态的纳米结构聚集体,将纳米粒子选择性的分布和定位于嵌段共聚物聚集体中,可以改善纳米粒子的性能及其应用.本文综述了近年来实验上利用自组装制备嵌段共聚物-纳米粒子复合纳米材料的方法,并总结分析了影响纳米粒子在嵌段共聚物聚集体中的分布和定位的各种因素,包括纳米粒子的大小、形状及其表面化学.最后总结了嵌段共聚物-纳米粒子的自组装在理论模拟方面的研究.     

多分散性对嵌段共聚物微观相行为影响的耗散粒子动力学模拟研究进展

嵌段共聚物通过微观相分离形成的各种有序结构在纳米印刷、药物输送、太阳能电池模板制备等领域有着广泛的应用.如何实现这些有序结构的有效调控是大家普遍关心的问题.近期的实验及理论研究表明嵌段长度的多分散性对嵌段共聚物的微观相行为有着不可忽视的影响.本文综述了近年来在AB型两嵌段及ABA型三嵌段共聚物的实验及理论研究中的一些主要进展,重点介绍了基于耗散粒子动力学的模拟研究进展.并对多分散性可能带来潜在重要影响的嵌段共聚物相关体系的未来发展方向进行了展望.     

梳型嵌段共聚物微观相分离的耗散粒子动力学模拟

利用耗散粒子动力学(Dissipative particle dynamics, DPD)模拟方法研究了二维梳型嵌段共聚物的微观相分离, 得到了相形貌与侧链长度及链段间相互作用的依赖关系, 进一步与线型和星型嵌段共聚物微观相分离进行了对比. 模拟结果揭示了本体中影响梳形嵌段共聚物微观相分离的主要因素, 包括嵌段共聚物的组成\, 拓扑结构以及不同粒子间的排斥力.     

稀溶液中Rod-Coil-Rod三嵌段共聚物组装结构的耗散粒子动力学模拟

采用耗散粒子动力学方法模拟研究了rod-coil-rod 三嵌段共聚物在稀溶液中的聚集行为. 分别考察了rod-coil 嵌段的相互作用、溶剂性质、共聚物浓度以及coil 嵌段长度对聚集体形貌的影响. 模拟结果发现,随着rod-coil 相互排斥作用的增加,共聚物由球形转变成洋葱状、笼形和柱状结构. 随着coil 嵌段疏水性的增加,笼形转变成洋葱状和补丁状结构. 给出了聚集体形貌随共聚物浓度和coil 长度变化的相图. 当浓度较小和coil 嵌段较长时,共聚物形成笼状聚集体,反之,则有利于洋葱状结构的形成.     

稀溶液中Rod-Coil-Rod三嵌段共聚物组装结构的耗散粒子动力学模拟（英文）

采用耗散粒子动力学方法模拟研究了rod-coil-rod三嵌段共聚物在稀溶液中的聚集行为.分别考察了rod-coil嵌段的相互作用、溶剂性质、共聚物浓度以及coil嵌段长度对聚集体形貌的影响.模拟结果发现,随着rod-coil相互排斥作用的增加,共聚物由球形转变成洋葱状、笼形和柱状结构.随着coil嵌段疏水性的增加,笼形转变成洋葱状和补丁状结构.给出了聚集体形貌随共聚物浓度和coil长度变化的相图.当浓度较小和coil嵌段较长时,共聚物形成笼状聚集体,反之,则有利于洋葱状结构的形成.     

表面图案诱导两嵌段共聚物形成穿孔层状结构的模拟

利用耗散粒子动力学方法研究了两嵌段共聚物在表面圆形图案诱导下的相行为.通过调节圆形诱导图案的半径和嵌段共聚物薄膜的厚度,体系出现了非常丰富的穿孔层状相结构(PLS).经过区分将这些结构分为4类,并用PLS-Ⅰ,PLS-Ⅱ,PLS-Ⅲ,PLS-Ⅳ表示.绘制了这些结构与圆形图案半径和薄膜厚度关系的相图,并分析了这些结构出现的原因和规律,为设计和发展嵌段共聚物功能薄膜材料提供理论支持.     

耗散粒子动力学与可极化ABEEM力场结合模拟嵌段共聚物自组装形态调控

本文采用介观尺度上的耗散粒子动力学与基于ABEEM可极化力场的全原子分子动力学相结合的方式,从理论上探究了嵌段共聚物结构、对称性、分子组成及温度等对嵌段共聚物最终自组装结构形态的影响.模拟结果表明,这些因素均会对嵌段共聚物在选择性溶剂中的最终自组装结构产生一定影响.这一理论研究为实现可控操纵自组装结构,提供了有意义的参考.     

两亲性/双疏性嵌段共聚物共混体系的自组装行为研究

采用耗散粒子动力学方法,研究了两亲性嵌段共聚物和双疏性嵌段共聚物共混体系的自组装行为,探讨了双疏性嵌段共聚物的浓度以及双疏性嵌段共聚物的嵌段体积分数对聚集体结构的影响.结果表明,随着双疏性嵌段共聚物浓度的增加,聚集体发生自囊泡到棒状胶束再到同心圆多舱胶束的转变,且当浓度较高时,同心圆多舱胶束的同心圆层数量与浓度密切相关.当双疏性嵌段共聚物中的嵌段体积分数降低时,球形胶束由同心圆结构转变为非同心圆结构.此外,利用Minkowski泛函方法表征了多舱胶束的形成过程,发现这是一个先形成大尺度球形结构、再形成小尺度内核结构的分级组装过程.     

均聚物链吸附在胶束表面上的非平衡态耗散粒子动力学

利用平衡态耗散粒子动力学（Dissipative Particle Dynamics, DPD）方法,研究了嵌段共聚物自组装形成胶束以及均聚物链在其表面的吸附。进一步采用非平衡态耗散粒子动力学（Non-Equilibrium Dissipative Particle Dynamics, NEDPD）方法,通过加入剪切,研究了均聚物的脱落和胶束的分裂过程。模拟结果揭示了脱落时间随剪切速率的变化规律。     

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.