抗菌聚合物纳米纤维的研究进展

静电纺丝技术是制备功能聚合物纳米纤维的一种简单而有效的方法。由电纺纳米纤维堆砌而成的无纺织物具有巨大的比表面积,赋予其广泛的应用前景。通过在电纺聚合物纳米纤维中添加各类抗菌剂或对其表面进行化学改性,制备具有优异抗菌性能的新型功能聚合物纳米材料,将进一步拓展电纺纳米纤维在生物医学、过滤、精密制造等领域的应用。本文基于抗菌纳米纤维的分类进行总结,介绍国内外抗菌聚合物纳米纤维的研究现状,并对抗菌纳米纤维的未来发展进行了探讨。     

静电纺丝——从无规纳米纤维膜到取向连续长纱

静电纺丝是通过对聚合物溶液或熔体施加外电场制造纳米纤维的有效方法.电纺过程中,在静电力作用下聚合物射流快速鞭动,形成的纳米纤维无规堆砌,得到无纺布状的无规纳米纤维膜.这种纳米纤维膜具有极大的比表面积,已用于超高效过滤,在刨伤修复、组织工程、水处理等领域有广泛的应用前景.为了进一步拓展纳米纤维在纤维工业、纺织品、微制造等领域的应用,电纺纳米纤维的取向和连续长纱的制备研究受到科学家的重视,文献报道了多种纳米纤维取向方法.本文分析了纳米纤维膜无规堆砌结构的形成机理,总结了纳米纤维取向研究和连续长纱制备研究进展,特别介绍了基于静电作用分析提出的共轭电纺方法,讨论了取向纳米纤维的应用以及纳米纤维未来的研究方向.     

电纺法制备聚合物纳米纤维的研究进展

电纺技术是一种制备聚合物纳米纤维的新方法,它可制备出直径为纳米级的超细纤维,最小直径可至1nm.电纺法制备聚合物纳米纤维具有设备简单、操作容易以及高效等优点,它是目前能直接、连续制备聚合物纳米纤维的有效方法.本文介绍了电纺过程、原理及影响纤维性能的主要因素,综述了电纺技术在生物医学材料,复合增强纤维,无机纳米纤维,导电纳米纤维等方面的应用进展,最后对电纺技术在制备聚合物纳米纤维方面的发展前景作出了展望.     

静电纺丝纳米纤维膜固定化酶及其应用*

静电纺丝是一种简单有效的制备聚合物纳米纤维的技术,在组织工程、药物控释和传感器等方面具有广泛的应用。采用静电纺丝技术制备得到的纳米纤维膜具有比表面积大、孔隙率高和易于分离回收等优点,可以作为一种优良的酶固定化载体,目前在酶固定化领域受到了广泛的关注。本文综述了近年来静电纺丝纳米纤维膜固定化酶的研究进展,在阐述静电纺丝纳米纤维膜制备技术的基础上,详细介绍了纳米纤维膜表面担载法和包埋法固定化酶的原理和方法,分析了不同固定化方法的优缺点,并讨论了静电纺丝纳米纤维膜固定化酶的应用前景,对静电纺丝纳米纤维膜固定化酶的发展方向进行了展望。     

静电纺丝制备图案化无机纳米纤维

静电纺丝技术近几年在制备纳米纤维领域得到了广泛的应用,被认为是批量制备纳米纤维材料最简单有效的方法。本文综述了近几年高压静电纺丝技术制备图案化无机物纳米纤维的纺丝装置和过程,特别详细综述了纺丝过程中纤维直径的变化,利用带电流体动力学(EHD)理论推导出纤维直径变化的运动方程,并对方程进行一定程度的修订,以符合电纺无机物纳米纤维直径的变化;并综述了取向纳米纤维、中空纳米纤维、壳-核结构纳米纤维、纳米线、纳米带、纳米管及多层次结构纳米纤维的构建及其基本性能。最后对电纺制备图案化无机纳米纤维未来发展方向,特别是功能化多层次结构电纺无机纳米纤维制备进行了展望。     

聚合物/TiO2杂化纳米纤维微孔膜的制备及其在染料敏化太阳能电池中的应用

利用静电纺丝技术,制备了不同的聚合物/TiO2杂化纳米纤维微孔膜,吸附液体电解质后形成聚合物/TiO2杂化纳米纤维微孔膜准固态电解质,应用于制备准固态染料敏化太阳能电池(DSSCs).测试了电纺聚合物纳米纤维微孔膜电解质的吸液率、孔隙率、离子电导率等参数,研究了纳米纤维微孔膜准固态电解质DSSCs的光伏性能.结果显示,TiO2的掺入可提高聚合物/TiO2杂化纳米纤维微孔膜对液态电解质的浸润扩散性能,从而提高纳米纤维微孔膜对液态电解质的吸附能力.组装的DSSCs的光电转换效率可达液态电解质的90%以上,并具有较好的长期工作稳定性.     

静电纺丝法制备聚酰亚胺新型材料

静电纺丝(eleetrospinning)是一种制备纳米尺度连续长丝的便捷高效的纺丝技术,其应用前景相当广阔.聚酰亚胺(polyimide,PI)是一类具有广泛应用的耐高温、高强度、综合性能优异的高分子材料.近10年来,利用电纺制备PI新型材料的报道层出不穷,包括利用PI电纺纤维为前躯体制备碳纤维材料,电纺制备PI纳米...     

静电纺荧光纳米纤维膜在痕量爆炸物检测中的应用

爆炸物检测作为打击爆炸恐怖主义的重要措施之一,正日益彰显出广阔的应用前景.其中,静电纺荧光纳米纤维膜在爆炸物检测领域已展现出其独特的优点,可满足爆炸物检测所需的检测速度快、检测灵敏度高等要求.本文总结了近年来静电纺荧光纳米纤维膜在爆炸物检测中的代表性成果,简要介绍了爆炸物荧光传感机理、静电纺丝技术原理、静电纺荧光纳米纤维膜的制备方法及其爆炸物检测性能的影响因素;系统、重点梳理了有机小分子体系、共轭聚合物体系、聚集诱导发光体系及其他荧光材料体系的静电纺荧光纳米纤维膜在爆炸物检测中的应用,并针对该领域尚未解决的问题和未来可能的发展方向进行了展望,可为实际爆炸物检测中静电纺荧光纳米纤维膜的设计提供指导.     

聚丙烯腈电纺纤维的功能化

聚丙烯腈是一种性能优异、应用广泛的成纤聚合物,静电纺丝技术则可用于制备聚丙烯腈纳米纤维,本文对聚丙烯腈纳米纤维的功能化进行了综述.通过表面仿生修饰、碳纳米管填充等方法改性的聚丙烯腈电纺纤维被尝试作为酶固定化的载体材料,在显著提高载酶量的同时,能大幅度提高酶活性.糖基功能化的纳米纤维对特定的蛋白质具有较高的识别效率,可望用于蛋白质的分离与纯化.卟啉化的聚丙烯腈电纺纤维则在显示出荧光特性的同时,在催化、传感等方面具有潜在的应用前景.     

可控核/壳结构聚合物电纺纤维的制备与应用

核/壳结构纳米纤维是一种兼具核层与壳层优异性能的功能化复合纤维, 通常具有优于核层和壳层自身的性能, 如可控的机械强度和较好的热传导系数等。其特殊的结构极大地提高了纤维的使用价值, 拓宽了纤维的应用领域, 因此, 核/壳结构纳米纤维成为纤维领域的研究热点之一。静电纺丝技术因其简单有效的特点, 近些年来在众多纳米纤维制备技术中一直备受关注, 制备结构和形貌可控的核/壳结构纤维的方法对于指导其在实际中的应用尤为重要。本文系统介绍了以静电纺丝技术制备核/壳结构纳米纤维的方法, 主要包括单喷头相分离法、同轴静电纺丝法、乳液静电纺丝法以及模板法, 重点讨论了影响核/壳结构的主要因素以及核/壳结构对纤维性能的影响。综述了近几年来国内外关于可控核/壳结构电纺纤维制备的研究新进展及其在药物缓释体系、组织工程支架、多功能敷料、污水处理材料、疏水性材料等领域的潜在应用价值。     

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%.     

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.     

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%).     

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.     

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.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

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.