聚丙烯腈纳米纤维的高效制备及结晶取向性能

分别采用传统静电纺丝装置和自行搭建的离心-静电纺丝装置制备出聚丙烯腈(PAN)纳米初生纤维,并在热空气浴中和一定外力作用下进行牵伸,牵伸后使其伸长至原长的1倍到3倍.通过广角X射线衍射(WAXD)、扫描电子显微镜(SEM)等方法对2种纺丝方法制备的PAN纳米初生纤维及经过热空气浴牵伸后的PAN纳米纤维的晶态结构、取向及形貌等进行了表征.研究表明:(1)离心-静电纺丝效率远高于静电纺丝,可达静电纺丝的120倍(离心-静电纺丝纺丝液流速为2 m L/min,静电纺丝纺丝液流速1 m L/h);(2)无论是离心纺丝还是静电纺丝制得的纳米初生纤维结晶度均很低(离心纺丝为25%,静电纺丝为10.1%),但离心纺丝制得的纳米初生纤维有一定的取向(60.5%),而静电纺丝基本没有;(3)经过热空气浴牵伸后,2种纺丝方式制得的纳米纤维结晶度均有所提高(分别为45.8%和36.2%),取向度也有所提高(分别为72.5%和59.8%),随着牵伸温度的提高和牵伸应力的增大,纤维的平均直径不断减小(离心纺丝由675 nm降至510 nm,静电纺丝由460 nm降至355 nm).纳米纤维在制备过程晶态结构及取向的效果有限,但通过热空气浴牵伸可以使晶态结构及取向得到进一步完善.     

聚合物的静电纺丝

静电纺丝法是聚合物溶液或熔体在静电作用下进行喷射拉伸而获得纳米级纤维的纺丝方法.由纳米纤维制得的无纺布,具有孔隙率高、比表面积大、纤维精细程度与均一性高、长径比大等优点,从而赋予了静电纺丝纤维广泛的应用前景,它已在国内外引起了广泛的关注.本文介绍了静电纺丝的装置、基本原理及静电纺丝制备纳米纤维的研究进展,同时也叙述了其在各个领域的应用,最后展望了静电纺丝制备纳米纤维的发展方向及前景.     

基于静电纺丝技术的取向纳米纤维

纳米纤维作为一维纳米材料的一个重要分支,有着广泛的应用前景。静电纺丝技术是一种制备一维纳米纤维的有效方法。然而,传统制备工艺制得的纳米纤维常为无序排列的结构,极大限制了其应用。近十几年来,通过对喷丝装置、纤维分化区及接收装置的改进获得了取向纳米纤维(aligned nanofibers, ANFs),引发了研究者的广泛关注,但对于取向纳米纤维的制备与应用未见系统性的论述。本文系统总结了采用静电纺丝技术制备取向纳米纤维的方法,并评述了这种取向结构在生物组织工程修复、传感器、增强材料及能源等领域中的应用。鉴于ANFs在生物组织工程中得到广泛的关注,本文对其进行了着重介绍。而在能源领域,本文主要阐述在质子交换膜燃料电池方面的应用。最后,本文总结了ANFs存在的问题,并展望了其未来的发展。     

静电纺聚丙烯腈纳米纤维晶态结构及取向的形成

采用新型流动水浴收集方式制备出连续单向排列的静电纺聚丙烯腈(PAN)纳米初生纤维,收集静电纺丝不同阶段的静电纺PAN纳米纤维,并在热水中进行后牵伸,使其伸长至原长的2倍、3倍.通过扫描电子显微镜(SEM)、广角X射线衍射(WAXD)等方法对静电纺丝过程不同阶段的PAN纳米纤维的形貌、直径、致密性、晶态结构及取向进行了表征.研究表明,(1)在静电纺丝过程中PAN纺丝液射流受到牵伸作用,静电纺PAN纳米纤维的晶态结构形成并逐渐完善.纳米纤维的直径随着静电纺丝过程逐渐减小(从664 nm减小至353 nm),结晶度从42.55％增加至47.76％,晶区取向由37.48％提高至43.93％.纳米纤维致密性也逐渐提高(密度由1.1917 g/cm3增加至1.1943 g/cm3).(2)静电纺丝过程进入PAN射流溶剂含量较低的阶段后,继续通过静电纺丝过程提高纳米初生纤维晶态结构及取向的效果很有限,而通过热水后牵伸过程可进一步使晶态结构及取向得到有效果的完善.研究同时发现,静电纺初生纤维的晶态结构及取向与其在热水牵伸过程中的进一步完善具有相关性.     

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。     

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。     

静电纺丝技术在二次电池和电催化领域的应用进展

静电纺丝技术是一种简单、高效制备一维纳米纤维的方法,其制备的纳米纤维一般经过后期热处理得到含碳复合物,具有操作简单、方法可控、产量可观等优点,得到的材料具有良好的导电性和快速的电子、离子传输路径,因此可用来广泛制备电极及催化材料.基于此,静电纺丝技术在二次电池(如锂/钠离子电池)和电催化领域有着广泛的应用.本综述不仅介绍了静电纺丝技术的原理,并且总结了其在纳米电极材料及催化领域的优势和标志性成果,并针对相关领域的问题进行了合理的探讨.此外,本文简要总结了现有的发展进程并指出了未来的发展方向,可对静电纺丝技术在先进能源材料的设计与制备上提供指导.     

基于静电纺丝技术的多级结构聚合物纳米纤维复合材料的研究进展

静电纺丝技术是目前制备纳米纤维最重要的方法之一,以其制备的纤维具有直径可控、比表面积大、孔隙率高等优点,因而被广泛应用于过滤、催化、传感器及生物医学等众多领域.以静电纺丝纤维为模板可进一步构建多级结构的功能性聚合物纳米纤维复合材料,拓宽其应用范围.本文着重概述了近年来基于静电纺丝技术的简单共混型、核壳结构及多级结构的聚合物纳米纤维复合材料的制备、结构及性能,并展望了其应用研究前景.     

静电纺丝法制备纳米抗菌纤维的研究进展

纳米抗菌材料是防止细菌等致病微生物对人们生产、生活的破坏而发展起来的一类新型材料.在纳米抗菌材料的众多制备方法中,静电纺丝是一种成本低,工艺可控的技术,制备的纳米纤维具有比表面积大、孔隙率高、纤维均匀等特点.本文作者首先简述了静电纺丝技术以及该技术制备纳米抗菌纤维材料的特点;接着按照菌剂种类不同,对静电纺丝技术制备的抗菌纤维材料进行归类,将其分为无机抗菌纤维材料、天然抗菌纤维材料和复合抗菌纤维材料3类,并对其研究进展进行了评述;最后对静电纺丝技术制备纳米抗菌纤维的研究现状进行了总结与展望.     

静电纺丝法制备纤维素纳米纤维的研究进展

纤维素纳米纤维很好的结合了纤维素的重要属性和纳米材料的各项特性,但纤维素大分子之间存在大量氢键,使得纤维素较难溶于普通溶剂,导致通过静电纺丝法直接制备纤维素纳米纤维具有一定的难度.而先采用静电纺丝法制备纤维素衍生物纳米纤维,再对纤维素衍生物纳米纤维进行水解也是制备纤维素纳米纤维的一种有效方法.本文对近年来这两种纤维素纳米纤维制备方法的研究进行了综述,并对静电纺制备纤维素纳米纤维的发展前景做出了展望.     

Controlled Nanofiber Composed of Multi‐Wall Carbon Nanotube/Poly(Ethylene Oxide)

We have successfully fabricated poly(ethylene oxide) (PEO) nanofibers containing embedded multi‐wall carbon nanotubes (MWCNTs). An initial dispersion of the MWCNTs in distilled water was achieved using sodium dodecyl sulfate. Subsequently, the dispersion was decanted into a PEO solution, which enabled separation of the MWCNTs and their individual incorporation into the PEO nanofibers on subsequent electrospinning. Initially, the carbon nanotube (CNT) rods were randomly oriented, but owing to the sink‐like flow in the electrospinning wedge, they became gradually oriented along the streaming direction, in order that oriented CNTs were obtained on entering the electrospun jet. Individual MWCNTs became embedded in the nanofibers, and were mostly aligned along the fiber axis. Evidence of load transfer to the nanotubes in the composite nanofiber was observed from the field‐emission scanning electron microscopy, transmission electron microscopy and conductivity data.     

Improved survival of cardiac cells on surface modified electrospun nanofibers

Polycaprolactone (PCL) is a popular synthetic polymer used in the field of cardiac tissue engineering (CTE) due to its non-toxic degraded by products and low cost manufacturing method. However, hydrophobic nature of this material limits its wide spread application in different cell interaction processes. Therefore, current study aims to chemically modify PCL made random and aligned nanofibers with collagen coating mimicking the oriented matrix of the cardiac cells. Morphological and chemical properties of the electrospun PCL nanofibers were evaluated by SEM, FTIR, XRD and water contact angle measurement. Results indicated that the anisotropic characteristics of aligned nanofibers promoted cell attachment and alignment, which closely match the requirements of native cardiac cells. Thus, aligned nanofibers could be preferred for cardiac tissue regeneration and defects over random nanofibers.     

Resorbable polymer electrospun nanofibers: History,shapes and application for tissue engineering

Resorbable polymer electrospun nanofiber-based materials/devices have high surface-to-volume ratio and often have a porous structure with excellent pore interconnectivity,which are suitable for growth and development of different types of cells.Due to the huge advantages of both resorbable polymers and electrospun nano fibers,re sorbable polymer electrospun nanofibers(RPENs)have been widely applied in the field of tissue engineering.In this paper,we will mainly introduce RPENs for tissue engineering.Firstly,the electrospinning technique and electrospun nanofiber architectures are briefly introduced.Secondly,the application of RPENs in the field of tissue engineering is mainly reviewed.Finally,the advantages and disadvantages of RPENs for tissue engineering are discussed.This review will provide a comprehensive guide to apply resorbable polymer electrospun nanofibers for tissue engineering.     

电纺法及其在制备聚合物纳米纤维中的应用

在介绍电纺法的基础上,对电纺法制备聚合物和导电聚合物纳米纤维的影响参数和电纺纤维的应用研究进行了综述,同时展望了该方法在制备聚合物纳米纤维方面存在的挑战和机遇。     

Processing and characterization of oriented electrospun poly(vinylidene fluoride) mats

Mats of highly oriented poly(vinylidene fluoride) nanofibers were electrospun by means of a conventional electrospinning equipment; the orientation, however, was obtained using a disk collector rotating at a speed of 4000 rpm and a device that reduced the influence of air displacement during nanofiber orientation. Thermal transitions of the mats were determined by differential scanning calorimetry, the predominant crystalline phase by Fourier transform infrared spectroscopy and wide‐angle X‐ray scattering and the nanofiber orientation and morphology by scanning electron microscopy. Relative permittivity, loss index, stable remnant polarization, and coercive field of the mats were also determined and compared with those obtained for a mat electrospun at 2000 rpm and an oriented commercial film. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 000: 000–000, 2012     

Uniaxially aligned carbon nanofibers derived from electrospun precursor yarns

Unlike conventional electrospun polymer fibers deposited on a target electrode as a randomly oriented mesh, poly(p‐xylenetetrahydrothiophenium chloride) was electrospun into centimeters‐long yarns vertically on the surface of the electrode but parallel to the electric field. The diameter of the yarn was strongly affected by the concentration, spinning rate, and viscosity of the polymer solution, but less dependent on the applied voltage. The subsequent carbonization of thus‐electrospun yarns at 600–1000 °C resulted in uniaxially aligned carbon nanofibers with average diameters of 127–184 nm. On the basis of Raman spectra, the graphitic crystallite size and the molar fraction of graphite were estimated to be 1.2–1.4 and 0.21–0.24 nm, respectively. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 305–310, 2008     

Electrospinning of polyurethane/organically modified montmorillonite nanocomposites

Polyurethane/organically modified montmorillonite (PU/O‐MMT) nanocomposites were electrospun and the effect of O‐MMT on the morphology and physical properties of the PU/O‐MMT nanofiber mats were investigated for the first time. The average diameters of the PU/O‐MMT nanofibers were ranged from 150 to 410 nm. The conductivities of the PU/O‐MMT solutions were linearly increased with increasing the content of O‐MMT, which caused a decrease in the average diameters of the PU/O‐MMT nanofibers. The as‐electrospun PU and PU/O‐MMT nanofibers were not microphase separated. The exfoliated MMT layers were well distributed within the PU/O‐MMT nanofibers and oriented along the fiber axis. When the PU/O‐MMT nanofibers were annealed, the exfoliated MMT layers hindered the microphase separation of the PU. The electrospinning of PU/O‐MMT nanocomposites resulted in PU nanofiber mats with improved Young's modulus and tensile strength. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 3171–3177, 2005     

Electrospun poly(3‐hexylthiophene)/poly(ethylene oxide)/graphene oxide composite nanofibers: effects of graphene oxide reduction

In this article, we report on the production by electrospinning of P3HT/PEO, P3HT/PEO/GO, and P3HT/PEO/rGO nanofibers in which the filler is homogeneously dispersed and parallel oriented along the fibers axis. The effect of nanofillers' presence inside nanofibers and GO reduction was studied, in order to reveal the influence of the new hierarchical structure on the electrical conductivity and mechanical properties. An in‐depth characterization of the purity and regioregularity of the starting P3HT as well as the morphology and chemical structure of GO and rGO was carried out. The morphology of the electrospun nanofibers was examined by both scanning and transmission electron microscopy. The fibrous nanocomposites are also characterized by differential scanning calorimetry to investigate their chemical structure and polymer chains arrangements. Finally, the electrical conductivity of the electrospun fibers and the elastic modulus of the single fibers are evaluated using a four‐point probe method and atomic force microscopy nanoindentation, respectively. The electrospun materials crystallinity as well as the elastic modulus increase with the addition of the nanofillers while the electrical conductivity is positively influenced by the GO reduction. Copyright © 2016 John Wiley & Sons, Ltd.     

Microstructural Study of Nylon-6/Gelatin Composite Nanofibers

Electrospinning is a simple and effective technology for fabricating nanofibers and polymer blending provides strength and minimal defects of electrospun ones. Therefore, in the present study, fabrication, and characterization of nylon-6/gelatin electrospun nanofibers using low-toxic solvents was investigated as means to improve the morphological deficiencies of gelatin nanofibers and facilitate its electrospinnability. The morphology of electrospun nylon-6/gelatin nanofibers were characterized using scanning electron microscope (SEM). SEM results showed that electrospun blend nanofibers had smooth surface with average diameter of from 40 to 100 nm; while, the miscibility of the blend and thermal behavior of nanofibers were determined using Fourier transform-infrared spectroscopy (FTIR) and differential scanning calorimeter (DSC). Water contact-angle measurement (WCA) was employed to investigating the wettability of nanofibers.