电机械聚合物人工肌肉材料的研究进展

模拟肌肉组织进行信息传递、能量转换、传动的人工肌肉驱动器成为新材料研发焦点。智能聚合物可以对外界刺激发生响应,产生形变,是制备人工肌肉的良好材料,已被广泛地用于机器人与智能机械系统,成为众多肌肉驱动器中的研究重点。本文主要总结电机械聚合物人工肌肉材料的研究进展,论述了静电作用、电热驱动、水/湿度驱动三种驱动方式的工作机理和研究进展,分析了聚合物人工肌肉材料驱动器发展过程中受到限制的关键因素,并对未来人工肌肉材料研究提出展望。     

仿生材料电活性聚合物“人工肌肉”的研究进展

自古以来,自然界就是人类各种技术思想、工程原理及重大发明的源泉.20世纪中期,人们越来越深刻认识到大自然的启发对于开发新材料和新技术的重要性,从而提出仿生学概念并建立仿生学这一学科.随着研究的发展,仿生学已成为自然科学的一个前沿和焦点.进入21世纪以来,随着机器人开发的不断深入以及人们对智能机械系统的强烈需求,作为机器人和智能机械系统驱动关键的人工肌肉已成为仿生领域的研究重点.电活性聚合物驱动器具有应变高、柔软性好、质轻、无噪声等特点,与肌肉有着极为相似的特性,甚至在一些方面的性能已经超过了肌肉,被公认为是最合适的仿肌肉材料,称之为"人工肌肉".近二十年来,在电活性聚合物驱动材料方面取得的研究进展使得仿生的"人工肌肉"研究得以飞速发展.     

烯碳材料在人工肌肉领域的应用进展

随着仿生机器人、智能控制及人工智能等领域的发展,传统的机械驱动方式已无法满足相关领域对致动系统提出的柔性、高效及多源刺激响应性等要求,因此需发展新型的人工肌肉材料。以碳纳米管和石墨烯为代表的烯碳材料具有轻质、高强、高电导率和柔性等特征,在人工肌肉领域展现出了巨大的应用潜力。以烯碳材料为基元构筑宏观组装体材料,或以烯碳材料为添加相制备纳米复合材料,可在微观和宏观架起桥梁,实现烯碳材料在人工肌肉领域的应用。本文基于上述两种应用形式,综述了烯碳材料在人工肌肉领域的应用进展。首先从一维纤维和二维薄膜的烯碳人工肌肉宏观表现形态出发,介绍了既作为结构材料,又提供了响应、驱动功能的烯碳材料在人工肌肉中的应用。接着从机电性能、可编程的响应形变以及传感功能三个方向,介绍了烯碳材料作为增强赋能相在人工肌肉材料中的功能性应用。最后阐述了基于烯碳材料人工肌肉的机遇与挑战。     

水凝胶仿生柔性电子学

水凝胶力学性质与生物组织相似,生物相容性好,在生物电子学领域具有独特的优势.受生物组织——如皮肤、神经、肌肉等启发,发展了具有仿生结构和功能的水凝胶材料.以这种水凝胶材料制作而成的柔性电子器件具有感知温度、压力、应变、电场等外界刺激的功能,可模拟生物组织的传感能力,在仿生电子皮肤,人工肌肉,人工神经等领域具有重要的应用...     

响应性交联液晶高分子仿生致动器的研究进展

交联液晶高分子兼具液晶取向有序性和交联聚合物熵弹性等特点,能够以动态可调节和可逆的方式来模仿生物体的行为,在仿生器件、柔性机器人、智能表面、生物医药等领域具有良好的应用前景.本综述总结了近几年智能响应性交联液晶高分子在仿生致动器方面的研究进展,从响应性交联液晶高分子的结构和驱动机理出发,讨论了响应性交联液晶高分子的合成工艺、制备技术和成型方法,以及响应性交联液晶高分子对光、热、磁、湿度的响应.此外,介绍了响应性交联液晶高分子致动器在柔性机器人、人工肌肉、微流体运输等领域的应用.最后,对响应性交联液晶高分子的发展前景进行了展望.这项工作主要讨论了响应性交联液晶高分子,旨在为具有新颖功能和更有挑战性的智能微型致动器提供新的设计思路.     

具有可编程形状变形的热响应超分子水凝胶

形状记忆水凝胶(SMHs)作为一种智能软材料备受关注.目前复杂的制备工艺和缓慢单一的形状变形阻碍了其在智能柔性驱动器中的应用.本研究以丙烯酰胺(AAm)、α-甲基丙烯酸(MAA)、丙烯腈(AN)为原料,N,N,N′,N′-四甲基乙二胺(TEMED)为促进剂,利用氢键和偶极-偶极相互作用的协同效应,简单自由基聚合方法构建了热响应形状记忆超分子水凝胶(P(AMA)).研究结果表明,水凝胶具有高韧性(1.11±0.06 MJ/m³),高拉伸强度(0.22±0.02 MPa)和超过1000%的应变.可逆物理交联点的解离和重建赋予了水凝胶优异的热响应形状记忆行为:在10℃条件下5 min即可固定为临时形状,并在37℃条件下10 s内恢复原始形状.本研究构建的P(AMA)形状记忆超分子水凝胶具有易制备、低成本、坚韧和可编程形状变形等优点,在柔性驱动器、软机器人和电子皮肤等领域具有良好的应用前景.     

纤维素基电致驱动器结构可能性与影响因素分析

验证了电致驱动纸(Electro-Active Paper-EAPap)作为驱动器的可能性,同时对其驱动影响因素进行了讨论。EAPap驱动器以纤维素基材料-纸制品作为基体,在基体两面层压了银质电极构成。当在电极上施加一个适当的电压时,EAPap驱动器将产生伸缩、弯曲等位移。实验结果表明,EAPap的驱动性能依赖于样品形式的选取,适宜的驱动电压和驱动频率,同时环境因素对驱动器性能的影响至关重要。另外,在对EAPap驱动器的驱动影响因素的研究中发现,胶的品种也对EAPap驱动器的驱动效果有一定的影响。研究结果表明,EAPap驱动器的电致驱动效应属于电致收缩效应。由于EAPap很容易制造而且轻便,很多领域可以得到应用,如柔性扬声器、活性吸音材料和智能成型控制元件等。     

光响应形变液晶聚合物的结构与应用

液晶聚合物能够在外界刺激下发生形状变化,是一类重要的柔性智能材料。其中液晶有序排列的改变诱导材料的宏观形变。光响应聚合物具有可远程操作、易于控制等特点,在刺激响应性聚合物的设计中受到了广泛关注。将具有光响应性的基团引入到液晶聚合物体系中,可以得到一系列具有重要应用前景的光致形变材料。本文综述了近年来光响应形变液晶聚合物的研究进展,总结了光响应液晶聚合物的分子设计与响应原理,包括光致异构化响应型、光致生热响应型和多重刺激响应型;介绍了光响应液晶聚合物柔性执行器在仿生功能、能量转换和柔性机器人等领域的应用;展望了未来的研究方向与应用前景。     

光致形变液晶高分子

交联液晶高分子兼具液晶的各向异性和高分子网络的弹性,并且具有优异的分子协同作用.在交联液晶高分子中引入光响应基团,例如偶氮苯后,即可赋予其光致形变性能,利用分子协同作用可以将光化学反应引起的分子结构变化放大为宏观形变,从而将光能直接转化成机械能.通过合理的分子结构和取向设计可以使液晶高分子产生诸如伸缩、弯曲、扭曲、振动等多种形式的光致形变,并用于各类光控柔性执行器件的构筑,在人工肌肉、微型机器人、微量液体操控等领域呈现出独特的优势和广阔的应用前景.本文总结和评述了光致形变液晶高分子的研究,包括材料结构对光致形变性能的影响、新型可加工光致形变材料的研究、利用可见光和近红外光触发形变的策略,以及光致形变液晶高分子微执行器在微量液体操控中的应用,最后展望了该领域的发展方向.     

基于液晶弹性体的软体机器人

作为热门的机器人研究方向,软体机器人通常由软材料制成,具有众多的自由度、能够承受大变形、连续变形和柔顺接触等优势,在微小物体操作和空间受限环境运动等特殊应用领域具有重要的研究价值。其中,液晶弹性体,作为一种最具代表性的智能材料,同时具有液晶各向异性和橡胶弹性,在外界刺激(热、光、电、磁、pH、湿度等)下,其相态或分子结构会产生变化,进而改变液晶基元的排列顺序,从而导致材料本身发生宏观形变,当撤去外界刺激后,液晶弹性体可以恢复到原来的形状。这种独特的双向形状记忆性能使液晶弹性体成为制备软体机器人最适宜的材料之一。目前,根据驱动方式的不同,液晶弹性体软体机器人的研究主要分为热驱动软体机器人、光驱动软体机器人、电驱动软体机器人及其他驱动类型软体机器人,如磁场驱动和湿度驱动液晶弹性体软体机器人等。本文综述了液晶弹性体软体机器人的研究进展,详细介绍了不同驱动方式的液晶弹性体软体机器人体系,并对液晶弹性体软体机器人的发展前景进行了展望。     

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.     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

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.     

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.     

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.     

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.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.