Fabrication of refining mesoporous silica nanofibers via electrospinning

Refining mesoporous silica nanofibers were fabricated by electrospinning method. A triblock copolymer (Pluronic, P123, H(C₂H₅O)₂₀(C₃H₇O)₇₀(C₂H₅O)OH) was used as the structure direction agent and polyvinyl pyrrolidone (PVP) was employed to prepare refining nanofibers. SEM images showed that the refining fibers had an average diameter about 200-300 nm with smooth surface. FT-IR spectrum and TGA curve proved that P123 and PVP were removed from the fibers after a thermal treatment. It was found that the obtained silica nanofibers had mesoporous structure. The pore structures were characterized by XRD and the N₂ adsorption-desorption isotherm.     

Fabrication and characterization of FePt magnetic nanofibers via electrospinning technique

L1₀-structured platinum–iron (FePt) nanofibers were successfully synthesized by electrospinning technique, followed by calcination and reduction processes. In the preparation procedure, ferrous chloride tetrahydrate [Fe(Cl)₂?4H₂O] and iron nitrate nonahydrate [Fe(NO₃)₃?9H₂O] were, respectively, used as iron sources contained in precursor solution for electrospinning. Subsequently, the FePt nanofibers were obtained from the calcination in air and the followed reduction in hydrogen (H₂) of the as-spun FePt/PVP composite nanofibers. The FePt nanofibers were characterized by X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, and superconducting quantum interference device magnetometry. It was found that the different iron salt used in the spinning solutions could highly affect the FePt nanofiber morphology, crystallite size, and the magnetic properties. The FePt nanofibers, resulted from the spinning solution containing iron dichloride tetrahydrate, were of better crystallinity and well-defined fibrous morphology with an average diameter of about 110 nm. Additionally, the considerably large coercivity of 10.27 kOe was recorded from the above FePt nanofibers.     

并列型静电纺丝法制备扭曲螺旋结构的复合微/纳米纤维与表征

采用并列型静电纺丝法成功制备出新型的扭曲螺旋结构的复合微/纳米纤维.主要使用扫描电镜、Smile View图像分析软件对样品的微观形貌及结构进行了表征和分析.分析结果表明,高收缩性聚酯弹性体TPEE和相对收缩率较低的PBT,在并列型电纺过程中因断裂伸长率不同产生不同程度的收缩,从而形成三维扭曲螺旋结构的复合纤维.所得纤...     

利用静电纺丝技术制备纳米黏土/聚乳酸复合纳米纤维与其表征

利用静电纺丝技术制备了纳米黏土/聚乳酸(PLA)复合纳米纤维,并将该复合纳米纤维收集成无纺布薄膜,采用SEM和TEM观察了复合纳米纤维的微观形貌和结构,分别利用XRD和TGA测试了复合纳米纤维的结晶行为及热学行为,并分析了复合纳米纤维薄膜的拉伸力学性能随纳米黏土含量的变化关系。结果表明:当PLA含量为10wt%、纳米黏土含量为1wt%、CHCl3与DMF体积比为3∶1溶剂条件下,所制备的纳米黏土/PLA复合纳米纤维的细度和均匀性均得到改善;XRD测试结果表明,纳米黏土成功附着在PLA中。TGA和力学测试结果表明,纳米黏土/PLA复合纳米纤维的热稳定性和力学性能相对于纯PLA纤维有较大幅度提高,当纳米黏土含量为1wt%时,其初始分解温度提高了60℃,拉伸强度、断裂伸长率和弹性模量分别提高了111.3%、74.9%和20.0%。     

Toward facile synthesizing of diamond nanostructures via nanotechnological approach: Lonsdaleite carbon nanofibers by electrospinning

Low cost synthesis of the diamond is a dream for the scientists. In this study, different forms of carbon were obtained due to utilizing of different cobalt-based catalytic materials in the graphitization of poly(vinyl alcohol) (PVA) electrospun nanofibers. The utilized cobalt-based catalysts were cobalt acetate tetrahydrate (CoAc), cobalt NPs, and CoAc/palladium NPs. Calcination in argon atmosphere of the polymeric nanofibers containing the aforementioned catalytic materials led to obtain different products. High yield and good nanofibrous morphology were obtained in case of CoAc-containing nanofibers, however cobalt nanoparticles destroyed the nanofibrous morphology and revealed low yield. Interestingly, diamond-like lonsdaleite carbon nanofibers were produced when CoAc–Pd NPs catalytic system was utilized; however normal graphite powder and nanofibers were obtained when Co NPs and CoAc have been used, respectively. The obtained Co-graphite and Co–Pd–lonsdaleite nanofibers could be also synthesized in the form of thin films supported on graphite disks when polyacrylonitrile disks were used as collectors. Calcination of the obtained disks with the attached electrospun nanofibers produced well affixed Co-graphite and Co–Pd–lonsdaleite nanofibers on graphite disks. Electrical properties study of the obtained films indicated that the Co–Pd–lonsdaleite nanofibers behave as semiconductor while Co-graphite nanofibers show ohmic conductivity. Magnetically, Pd has a negative impact on the magnetic properties of the cobalt.     

Preparation and electrical characterization of polyamide-6/chitosan composite nanofibers via electrospinning

We report on the preparation and electrical characterization of polyamide-6/chitosan composite nanofibers. These composite nanofibers were prepared using a single solvent system via electrospinning process. The resultant nanofibers were well-oriented and had good incorporation of chitosan. Current-voltage (I-V) measurements revealed interesting linear curve, including enhanced conductivities with respect to chitosan content. The electrical conductivity of the polyamide-6/chitosan composite nanofibers increased with increasing content of chitosan which was attributed to the formation of ultrafine nanofibers. In addition, the sheet resistance of composite nanofibers was decreased with increasing chitosan concentration.     

Preparation of pure iron nanofibers via electrospinning

In this paper, iron nanofibers were successfully produced by electrospinning of ferric nitrate-PVA solutions to corresponding PVA/Fe(NO₃)₃ composite nanofibers followed by calcinations and reduction. The thermal stability of the as-prepared PVA/Fe(NO₃)₃ composite nanofibers were investigated by TG-DSC. The morphologies and structures of the as-prepared samples were also characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results obtained indicated that: the thermal transformation of ferric nitrate and the decomposition of PVA in PVA/Fe(NO₃)₃ composite nanofibers ended at 310 °C and 460 °C respectively. The as-prepared iron nanofibers showed a continuous morphology and a very high degree of crystallization. Furthermore, the average diameter was about 180 nm.     

Fabrication of WO3 nanofibers by high voltage electrospinning

Mixtures of 0.1, 0.3, and 0.5 mmol ammonium metatungstate hydrate (AMH), and poly (vinyl alcohol) (PVA) were electrospun by a + 20 kV direct voltage to synthesize fibers. Those of 0.5 mmol AMH were further calcined to have PVA removed and crystalline degree improved. At 500 °C and 2 h calcination, WO₃ nanofibers, including two main stretching modes, 3.24 eV direct energy gap, and 378 nm wavelength violet emission were detected. A possible formation mechanism of WO₃ nanofibers was proposed according to the experimental results.     

Preparation and electrochemical performances of LiFePO4/C composite nanobelts via facile electrospinning

LiFePO₄/C composite nanobelts were synthesized by calcination of the [LiOH + Fe(NO₃)₃ + H₃PO₄]/polyvinyl pyrrolidone (PVP) electrospun nanobelts. PVP was used as the electrospinning template and carbon source. During the calcination, [LiOH + Fe(NO₃)₃ + H₃PO₄] were transformed to lithium iron phosphate (LiFePO₄) and PVP was decomposed into carbon. The morphology and properties of the as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller (BET) specific surface area analysis, electrochemical impedance spectroscopy and galvanostatic charge–discharge measurements. The results indicate that the mean width of LiFePO₄/C composite nanobelts is 2.50 ± 0.33 μm, the average thickness is about 162 nm and the BET specific surface area is 19.4 m² g^?1. The addition of carbon does not affect the structure of LiFePO₄, but improves its electrochemical performances. At the current density of 0.2 C, the initial discharge capacity of LiFePO₄/C electrode is 123.38 mAh g^?1 and there is no obvious capacity fading after 50 cycles. The formation mechanism of LiFePO₄/C composite nanobelts was also proposed.     

Fabrication and characterization of Fe-Ni alloy/nickel ferrite composite nanofibers by electrospinning and partial reduction

A novel synthetic process has been developed to fabricate the magnetic alloy/spinel ferrite composite nanofibers. By employing the electrospinning technique and subsequent partial reduction, Fe-Ni alloy/nickel ferrite composite nanofibers with an average diameter of around 170 nm were successfully prepared. The synthesized composite nanofibers consist of the face centered cubic and body centered cubic phases of Fe-Ni alloy and the spinel phase of nickel ferrite, and have novel magnetic properties with much enhanced coercivity and saturation magnetization as compared with the pristine nickel ferrite nanofibers.     

Fabrication of TiO2/ZnO composite nanofibers by electrospinning and their photocatalytic property

TiO₂/ZnO composite nanofibers with diameters in the range of 85–200 nm were fabricated via the electrospinning technique using zinc acetate and titanium tetra-isopropoxide as precursors, cellulose acetate as the fiber template, and N,N-dimethylformamide/acetone 1:2 (v/v) mixtures as the co-solvent. After treated with 0.1 mol/L NaOH aqueous solution, TiO₂/zinc acetate/cellulose acetate composite nanofibers were transformed into TiO₂/Zn(OH)₂/cellulose composite nanofibers. TiO₂/ZnO composite nanofibers were obtained by calcinating the hydrolyzed composite fibers at 500 and 700 °C for 5 h. The structure and morphology of composite nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, energy dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. With the blending of ZnO into TiO₂, a new crystallite ZnTiO₃ was formed in addition to the ZnO and TiO₂ crystallites, and the ultraviolet light absorption efficiency was enhanced according to the UV–vis diffuse reflectance spectroscopy. The photocatalytic activity of TiO₂/ZnO composite nanofibers toward the decomposition of Rhodamine B and phenol was investigated. Almost 100% Rhodamine B and 85% phenol were decomposed in the presence of TiO₂/ZnO composite nanofibers under mild conditions. The results demonstrated that the blending of ZnO in the TiO₂/ZnO composite nanofibers increased the photocatalytic efficiency. The optimum ZnO content in the TiO₂/ZnO composite nanofibers was 15.76 wt% to reach the most efficient photocatalytic activity. A schematic diagram of photocatalytic mechanism of TiO₂/ZnO composite nanofibers was also presented.     

Preparation of photocrosslinkable polystyrene methylene cinnamate nanofibers via electrospinning

Nanoscaled photocrosslinkable polystyrene methylene cinnamate (PSMC) nanofibers were fabricated by electrospinning. The PSMC was prepared by the modification of polystyrene as a starting material via a two-step reaction process, chloromethylation and esterification. The chemical structure of PSMC was confirmed by 1H NMR and Fourier transform infrared spectroscopy (FT-IR). The photosensitivity of the PSMC was investigated using ultraviolet (UV) spectroscopic methods. Electrospun PSMC nanofiber mat showed excellent solubility in many organic solvents. UV irradiation of the electrospun mats led to photodimerization to resist dissolving in organic solvents. The morphology of the nanofiber was observed by scanning electron microscopy (SEM) and the result indicated that the average diameter of nanofibers is 350 nm and the crosslinked nanofibers were not collapsed after dipping into organic solvent showing good solvent-stability. This photocrosslinked nanofibers has the potential application in filtration, catalyst carrier and protective coating.     

Fabrication of aligned poly (vinyl alcohol) nanofibers by electrospinning

Electrospinning has become a versatile tool for fabricating nanofibers from materials of diverse origins. Normally, mats of randomly-aligned fibers were obtained. A number of techniques have been proposed to arrive at uniaxially-aligned fibers. This work reports a new technique, i.e., dual vertical wire technique, for fabrication of uniaxially-aligned fibers. This technique utilized two stainless steel wires that were vertically set in a parallel manner between a charged needle and a grounded collector plate. This technique allowed simultaneous collection of aligned fibers (between the parallel vertical wires) and a randomly-aligned fiber mat (on the collector plate). Application of the technique on poly(vinyl alcohol) (PVA) to prepare uniaxially-aligned fibers was found to be successful at short collection times. Unexpected formation of a large fiber tow consisting of individual as-spun nanofibers that were bound into a bundle was observed at long collection times. Morphological appearance and size of the fiber tow was affected by the change in the distance between the two vertical wire electrodes, while the average diameter of the individual fibers was not (i.e., about 340 to 350 nm). Lastly, mechanical properties and thermal behavior of the fiber tow were also investigated.     

Fabrication of multi-walled carbon nanotube reinforced polyelectrolyte hollow nanofibers by electrospinning

Hybrid hollow multi-walled carbon nanotubes (MWCNTs)/polyelectrolytes (PE) nanofibers were prepared by a combination of the electrospinning method and layer-by-layer (LbL) technique. The mixed polystyrene (PS)/MWCNTs nanofibers were obtained by electrospinning method, which were employed as templates to self-assembly multilayered polyelectrolytes by LbL technique. Hollow MWCNTs/PE nanofibers were obtained by selectively removed part of the template: PS, which is confirmed by Raman spectra, transmission electron microscopy (TEM) and scanning electron microscopy (SEM).     

静电纺丝法制备氧化物纳米纤维及其气敏特性

静电纺丝技术由于简单的装置和制备过程,以及所使用材料的多样和应用领域的广泛,被认为是制备纳米纤维材料最具发展潜力的方法.简述了静电纺丝技术和影响纺丝质量的相关因素;介绍了静电纺丝制备半导体氧化物纳米纤维的方法及纳米纤维在气体传感器领域的应用;比较了几种纳米纤维和纳米线纳米棒等气敏元件的敏感特性;最后分析了纳米纤维具有优...     

Solution- and air-recoverable photocatalytic nanofibers by facile and cost-effective electrospinning and co-precipitation processes

While nanostructured materials are of particular academic and practical interest, their recoverability and recyclability have been of paramount industrial and environmental concerns. In the present contribution, co-precipitation was demonstrated as a facile and cost-effective approach to incorporate magnetic sensitivity and enhance the recoverability of nanofibrous materials which were frequently utilized in catalysis, energy and medical applications, etc. In particular, reusable magnetic and photocatalytic hybrid nanofibers were generated by electrospinning and co-precipitation method. First, TiO₂ nanofibers were prepared through sol-gel reaction and electrospinning process. To improve their recoverability, CoFe₂O₄ nanoparticles were decorated onto the nanofibers' surfaces via co-precipitation of cobalt and iron ions in the presence of the nanofibers suspension. Furthermore, the resulting CoFe₂O₄-decorated TiO₂ nanofibers maintained their photocatalytic activity after the modification. When suspended in a solution or spread on a dried surfaces, these nanofibers could be recollected with a magnet. These findings suggested that incorporation of ferromagnetic into the nanofibers maintained their photocatalytic performance and reduced production cost as well as the risk of human and environmental exposure through solution and air.     

A simple one-step fabrication of short polymer nanofibers via electrospinning

Short polymer nanofibers were successfully fabricated by electrospinning, a solution composed of a polymer cellulose acetate, acetone, and dimethyl acetamide. The concentration of the polymer in the solution ranged from 13 to 15 wt% and was the most important factor in the fabrication of short nanofibers. The lengths of the short nanofibers were changed via the flow rate of the polymer solution along with the applied voltage. The length was increased by increasing the flow rate of the solution, and it was decreased with an increase in the applied voltage, resulting in a length of short nanofibers that could be controlled at 37–670 μm. The polymer solution jet ejected straight from the needle tip, but then it was spread due to lateral perturbations on the surface of the polymer solution. A rapid increase in the repulsive force from surface charges combined longitudinal forces from the applied voltage split the solution jet and segmented the nanofibers.     

Fabrication of a composite vascular scaffold using electrospinning technology

Intermolecular forces and morphology demonstrated that there was an excellent compatibility between silk fibroin and gelatin. The silk fibroin/gelatin composite vascular scaffold (inner diameter 4.5 mm) was prepared successfully by electrospinning. The scaffold was treated with ethanol to enhance the water-resistant ability and biomechanical properties. After ethanol treatment, the scaffold could hardly dissolve in the water, and FTIR showed that the conformation of the treated silk fibroin/gelatin composite vascular scaffold was mainly β-sheets. The electrospun silk fibroin/gelatin vascular scaffold possessed outstanding biomechanical properties. In vitro cell culture and in vivo subcutaneous implantation demonstrated that the electrospun silk fibroin/gelatin vascular scaffold had an appropriate biocompatibility. The results indicated that the electrospun silk fibroin/gelatin composite vascular scaffold could be considered as an ideal candidate for tissue-engineered blood vessel.