静电纺丝制备聚丙烯腈纳米碳纤维

利用静电纺丝制备连续的聚丙烯腈纳米碳纤维;介绍了静电纺丝的原理、影响静电纺丝的主要因素以及制备纳米碳纤维、纳米活性炭纤维、纳米碳纤维复合材料的方法和原理;分析了静电纺丝产率低,难以得到单向平铺的纤维等问题,影响静电纺丝的参数主要有溶液特性、纺丝工艺参数、纺丝环境参数。由静电纺丝得到纳米聚丙烯腈纤维,然后再经预氧化和碳化制备纳米碳纤维,或把纳米纤维预氧化,经活化、碳化制备纳米活性炭纤维。并指出纳米碳纤维具有巨大的潜在应用空间。     

Fabrication and characterization of carbon nanofibers with a multiple tubular porous structure via electrospinning

Carbon nanofibers with a multiple tubular porous structure were prepared via electrospinning from a polymer blend solution of polyacrylonitrile (PAN) and polylactide (PLA) followed by carbonization. The electrospun composite nanofibers underwent pre-oxidization and carbonization, which selectively eliminated PLA phases and transformed the continuous PAN phase into carbon, thereby porous structure formed in the carbon nanofibers. The morphologies of as-spun, pre-oxidized and carbonized nanofibers were studied by scanning electron microscope (SEM) and transmission electron microscopy (TEM). It was found that carbon nanofibers with an average diameter about 250 nm and a multiple tubular porous structure were obtained. The chemical changes during thermal treatment were studied by Fourier transform infrared spectrometer (FTIR), Raman spectra, differential thermal analysis (DTA) and thermogravimetric analysis (TG). The results showed that PLA phases were effectively removed and the continuous PAN phase was completely carbonized. The obtained carbon nanofibers had more disordered non-graphitized structures than non-porous nanofibers.     

Biocidal nanofibers via electrospinning

To achieve biocidal properties, a cyclic N‐halamine precursor, 7,7,9,9‐tetramethyl‐1,3,8‐triazaspiro[4.5]‐decane‐2,4‐dione (TTDD), was synthesized and introduced into nanosized polyacrylonitrile fibrous mat by an electrospinning technique. It was rendered antimicrobial by exposure to dilute hypochlorite solution. Synthesis routes and characterization data are presented. Scanning electron microscopy (SEM) demonstrated that the ultrafine fiber possessed average diameter 414 nm (from 240 to 650 nm). The chlorinated nanofibrous composites provided about 4.9 log reductions of both Gram‐positive bacteria Staphylococcus aureus (ATCC 6538) and Gram‐negative bacteria Escherichia coli O157:H7 (ATCC 43895) within 5 min of contact time. This is indicative of promising possible applications in the filtration of water and air. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

电场纺丝法制备纳米纤维材料研究进展

从原理、装置、研究体系以及应用等方面阐述了电场纺丝技术近几年的发展情况,着重介绍了国内外在电场纺丝所得纤维的具体形态方面的研究.与传统方法相比,用该方法制备的纤维受到很多因素的影响,因而表面形态各异,比表面积较大,在医药、功能材料等方面都有广泛应用.虽然存在纺丝过程效率较低,溶剂存在环保等问题,但依旧是一种很有前途的纤维制造技术.     

Polymeric nanofibers via flat spinneret electrospinning

Electrospun nanofibers are most often produced by needle electrospinning process, which has inherent disadvantages like clogging and low efficiency. In this study, an alternative needleless electrospinning process is reported for the fabrication of nanofibers based on a novel spinneret. Firstly, a spinneret with a 0.5‐mm diameter hole in the middle of a flat plastic cap was custom‐made that may be readily scaled up for mass production. Then, polyethylene oxide (PEO) aqueous solution with 6.0 wt% concentration was used to demonstrate the needleless electrospinning process. The processing window for the jet formation in the flat spinneret electrospinning process was determined. The relationships between various processing parameters (applied voltage, working distance, and flow rate) and the resultant PEO nanofibers were also investigated. It was found that stable fluid jet launched from the tip of the coned droplet anchored at the rim of the hole and formed fibers. The morphology and diameter of electrospun fibers were examined using scanning electron microscopy. The results show that PEO nanofibers produced by this needleless electrospinning have similar structure and morphology to those from the single needle source. Finally, the hole number of spinneret was increased to four holes, which was still able to produce smooth nanofibers with a higher production rate. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Activated porous carbon nanofibers using Sn segregation for high-performance electrochemical capacitors

Activated porous carbon nanofibers (CNFs) with three different types of porous structures, which were controlled to contain 1, 4, and 8 wt% of Sn–poly(vinylpyrrolidone) (PVP) precursors in the core region and 7 wt% polyaniline (PAN)–PVP precursors in the shell region during electrospinning, were synthesized using a co-electrospinning technique with H₂-reduction. The formation mechanisms of activated porous CNF electrodes with the three different types of samples were demonstrated. The activated porous CNFs, for use as electrodes in high-performance electrochemical capacitors, have excellent capacitances (289.0 F/g at 10 mV/s), superior cycling stability, and high energy densities; these values are much better than those of the conventional CNFs. The improved capacitances of the activated porous CNFs are explained by the synergistic effect of the improved porous structures in the CNF electrodes and the formation of activated states on the CNF surfaces.     

Synthesis of multi-branched porous carbon nanofibers and their application in electrochemical double-layer capacitors

Multi-branched carbon nanofibers with a porous structure have been synthesized on a Cu catalyst doped with Li, Na, or K. The products were characterized by field emission scanning electron microscopy, transmission electron microscopy, high-resolution transmission electron microscopy and Raman spectroscopy. Using this new type of nanofiber as polarized electrodes, an electrochemical double-layer capacitor with a specific capacitance of ca. 297 F/g was obtained using 6 M KOH as the electrolyte.     

Synthesis and characterization of calcium zirconate nanofibers produced by electrospinning

Calcium zirconate fibers were produced by electrospinning and characterized in this work. The solution was prepared from zirconium and calcium salts, using polyvinyl-pyrrolidone (PVP) as processing aid. The decomposition of the organic fraction and crystallization of calcium zirconate were followed by thermogravimetry and differential scanning calorimetry (TG/DSC). Raman Spectroscopy was used to measure the vibrational modes in the green as well as in the calcined fibers. The final phase composition was studied by means of X-ray diffraction (XRD). The fiber morphology was investigated by confocal laser scanning microscopy (CLS) and scanning electron microscopy (SEM). The formation reaction of calcium zirconate was observed at about 740 °C. Highly crystalline fibers were obtained already at 800 °C, but the crystallinity and calcium zirconate yield improved when the temperature was increased to 1000 °C.     

Fabrication of cadmium titanate nanofibers via electrospinning technique

Here we present an electrospinning technique for the fabrication of cadmium titanate/polyvinyl-pyrrolidone composite nanofibers. The composite nanofibers are then annealed at 600 °C to obtain ilmenite rhombohedral phase cadmium titanate nanofibers. The structure, composition, thermal stability and optical properties of as synthesized and annealed cadmium titanate nanofibers are characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy and ultraviolet–visible spectroscopy. The average diameter and length of the nanofibers are found to be ～150–200 nm and ～100 μm, respectively.     

Conductive polypyrrole nanofibers via electrospinning: Electrical and morphological properties

Conductive polypyrrole nanofibers with diameters in the range of about 70-300 nm were obtained using electrospinning processes. The conductive nanofibers had well-defined morphology and physical stability. Two methods were employed. Electrospun nanofibers were prepared from a solution mixture of polypyrrole (PPy), and poly(ethylene oxide) (PEO) acted as a carrier in order to improve PPy processability. Both the electrical conductivity and the average diameter of PPy nanofibers can be controlled with the ratio of PPy/PEO content. In addition, pure (without carrier) polypyrrole nanofibers were also able to be formed by electrospinning organic solvent soluble polypyrrole, [(PPy3)⁺ (DEHS)⁻]_x, prepared using the functional doping agent di(2-ethylhexyl) sulfosuccinate sodium salt (NaDEHS) [Jang KS, Lee H, Moon B. Synth Met 2004;143:289-94. [24]]. Electrospun blends of sulfonic acid (SO₃H)-bearing water soluble polypyrrole, [PPy(SO₃H)-DEHS], with PEO acting as a carrier, are also reported. The factors that facilitate the formation of electrical conduction paths through the electrospun nanofiber segments are discussed.     

Bipolymer nanofibers: Engineering nanoscale interface via bubble electrospinning

Modern applications in biomedicine, drug delivery, and tissue engineering demand versatile materials capable of meeting multifaceted requirements. Conventional mono-functional materials fall short of addressing these complex demands. To tackle this challenge, this study introduces an innovative approach utilizing bubble electrospinning for the fabrication of bipolymeric side-by-side nanofibers. These nanofibers incorporate distinct hydrophilic and hydrophobic domains aligned parallel to their axis, achieved through the electrospinning of polyvinyl alcohol (PVA) as the hydrophilic component, alongside either poly(ε-caprolactone) (PCL) or Nylon6 as the hydrophobic component. The optimal diameter of the bubble electrospinning reservoir was theoretically determined via simulation of electric field using Maxwell 3D software and experimentally validated. Successful electrospinning resulted in nanofibers with hydrophilic and hydrophobic domains derived from PVA/Nylon6 and PVA/PCL polymer combinations. This innovative process yielded nanofibers with diameters as fine as 101 nm in the PVA/Nylon6 bipolymeric nanofibers. Transmission electron microscopy images provide compelling insights into the distinct interfaces formed during polymer-polymer interactions within the nanofibers, manifesting the Janus structure. Furthermore, Fourier-transform infrared spectroscopy confirms the presence of both polymers within the nanofiber matrix. This research represents a significant advancement in the efficient production of bipolymer nanofibers, holding promise for a wide range of applications.     

The production of porous carbon nanofibers from cross-linked polyphosphazene nanofibers

Uniform porous carbon nanofibers with an average diameter of 90 nm were fabricated by forming polyphosphazene nanofibers and carbonizing them, without the need for any activation step. The structure and morphology of the carbon nanofibers were characterized by SEM, TEM, EDX, XRD, Raman spectrum and N₂ adsorption. Results showed that the carbon nanofibers have a BET surface area of about 540 m² g⁻¹, a total pore volume of about 0.37 m³ g⁻¹, and a narrow pore size distribution in the micropore range.     

Fabrication of magnetic nanofibers via surface-initiated RAFT polymerization and coaxial electrospinning

A simple and continuous approach for fabricating magnetic polyacrylonitrile nanofibers (MNFs) with the diameter of about 200 nm has been developed by combining surface-initiated reversible addition-fragmentation chain transfer (RAFT) polymerization and coaxial electrospinning. The RAFT polymerization of acrylonitrile was carried out on the surface of RAFT agent immobilized Fe₃O₄ nanoparticles. The room-temperature saturation magnetizations of the prepared MNFs can be easily adjusted. In addition, the aligned fibers can be conveniently obtained via magnetic electrospinning using a specially designed fiber collector.     

Preparation of porous nylon 6 fiber via electrospinning

Porous nylon‐6 fibers were obtained by electrospinning of ultra‐high molecular polyamide 6 (UHMW‐PA6). First, UHMW‐PA6/calcium formate composite nanofibers were prepared as precursors by electrospinning UHMW‐PA6 solutions containing different contents of calcium formate particles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and inner structure of composite nanofibers. It was found that calcium formate particles were distributed both inside and on the surface of nanofibers. Fourier transform infrared (FTIR), differential scanning calorimetry, and thermal gravimetric analysis (TGA) were used to study the structure and properties of these nanofibers. Then, porous UHMW‐PA6 nanofibers were obtained by soaking the electrospun web in water for 24 h, to remove calcium formate particles. The removal of calcium formate particles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of porous structure in these nanofibers. In addition, CaCl₂ was used instead of calcium formate to prepare the UHMW‐PA6 nanoporous fiber. POLYM. ENG. SCI., 55:1133–1141, 2015. © 2014 Society of Plastics Engineers     

Highly porous Ti4O7 reactive electrochemical water filtration membranes fabricated via electrospinning/electrospraying

Porous, flexible, reactive electrochemical membranes (REMs) for water purification were synthesized by a novel simultaneous electrospinning/electrospraying (E/E) technique, which produced a network of poly(sulfone) fibers and Ti₄O₇ particles as evidenced by scanning electron microscopy. Cyclic voltammetry indicated that the kinetics for water electrolysis reactions and the Fe(CN)₆^4?/3? redox couple were enhanced by Ti₄O₇ deposition using the E/E technique. Membrane filtration experiments using phenol as a model contaminant showed a 2.6‐fold enhancement in the observed first‐order rate constant for phenol oxidation (k_obs,phenol) in filtration mode relative to cross‐flow operation. Phenol oxidation in filtration mode was approaching the pore diffusion mass transfer limit, and was 6 to 8 times higher than measured in a previous study that utilized a ceramic Ti₄O₇ REM operated in filtration mode and is comparable to rate constants obtained with carbon nanotube flow‐through reactors, which are among the highest reported in the literature to date. © 2015 American Institute of Chemical Engineers AIChE J, 62: 508–524, 2016     

Multiwalled carbon nanotubes incorporated bombyx mori silk nanofibers by electrospinning

In this work, the regenerated silk protein with multiwalled carbon nanotubes (MWNT) was successfully electrospun in formic acid to generate the hybrid silk nanofibers. The morphology, structure and mechanical properties of the resulting silk/MWNT hybrid nanofibers were characterized using field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FI-IR), Raman spectroscopy, wide angle X-ray diffraction (WAXD) and tensile testing. Thermo analysis was also carried out. TEM results confirmed that MWNT were well incorporated into the silk fibers. Addition of MWNT into silk nanofibers resulted in an enhanced mechanical property depending on MWNT content.     

Preparation of porous carbon nanofibers derived from graphene oxide/polyacrylonitrile composites as electrochemical electrode materials

Porous carbon nanofibers (CNFs) derived from graphene oxide (GO) were prepared from the carbonization of electrospun polyacrylonitrile nanofibers with up to 15 wt.% GO at 1200 °C, followed by a low-temperature activation. The activated CNFs with reduced GOs (r-GO) revealed a specific surface area and adsorption capacity of 631 m²/g and 191.2 F/g, respectively, which are significantly higher than those of pure CNFs (16 m²/g and 3.1 F/g). It is believed that rough interfaces between r-GO and CNFs introduce oxygen pathways during activation, help to produce large amounts of all types of pores compared to pure activated CNFs.     

Preparation and characterization of polymer‐Ti3C2Tx (MXene) composite nanofibers produced via electrospinning

MXene, a recently‐discovered family of two‐dimensional (2D) transition metal carbides and/or nitrides, have attracted much interest because of their unique electrical, thermal, and mechanical properties. In this study, poly(acrylic acid), poly(ethylene oxide) (PEO), poly(vinyl alcohol) (PVA), and alginate/PEO were electrospun with delaminated Ti₃C₂ (MXene) flakes. The effect of small additions of delaminated Ti₃C₂ (1% w/w) on the structure and properties of the nanofibers were investigated and compared with those of the neat polymer nanofibers using scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, and Fourier transform infrared spectroscopy. Ti₃C₂ had an effect on the solution properties of the polymer and a greater effect on the average fiber diameter. The Ti₃C₂T_x/PEO solution exhibited the largest change in viscosity and conductivity with an 11% and 73.6% increase over the base polymer, respectively. X‐ray diffractograms demonstrated a high degree of crystallization for Ti₃C₂/PEO and a slight decrease in crystallinity for Ti₃C₂/PVA. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45295.     

Preparation of chitosan bicomponent nanofibers filled with hydroxyapatite nanoparticles via electrospinning

Chitosan (CS) bicomponent nanofibers with an average diameter controlled from 100 to 50 nm were successfully prepared by electrospinning of CS and poly(vinyl alcohol) (PVA) blend solution. Finer fibers and more efficient fiber formations were observed with increased PVA contents. On this contribution, a uniform and ultrafine nanofibrous CS bicomponent mats filled with hydroxyapatite (HA) nanoparticles were successfully electrospun in a well devised condition. An increase in the contents of HA nanoparticles caused the conductivity of the blend solution to increase from 1.06 mS/cm (0 wt % HA) to 2.27 mS/cm (0.5 wt % HA), 2.35 mS/cm (1.0 wt % HA), respectively, and the average diameter of the composite fibers to decrease from 59 ± 10 nm(0 wt % HA) to 49 ± 10 nm (0.5 wt % HA), 46 ± 10 nm (1.0 wt % HA), respectively. SEM images showed that some particles had filled in the nanofibers whereas the others had dispersed on the surface of fibers, and EDXA results indicated that both the nanoparticles filled in the nanofibers and those adhered to the fibers were HA particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010