Fabrication and morphological study of converged SiC-TiC fiber mats by electrospinning

Titanium-containing silicon carbide (SiC) fiber mats were fabricated by an electrospinning method followed with a polymer-derived ceramics route. Titanium isopropoxide was used to cross-link into polycarbosilane (PCS) in toluene and xylene contained in the medium. The mat structure, fiber morphology, and crystallization of the fabricated SiC fibrous mat were analyzed by scanning electron microscopy and X-ray diffraction. According to the analysis results, the ceramic yield of the precursor increased significantly because of the high degree of cross-linking in PCS molecular structure.     

Fabrication and characterization of PCL/gelatin composite nanofibrous scaffold for tissue engineering applications by electrospinning method

In the present study, composite nanofibrous tissue engineering-scaffold consisting of polycaprolactone and gelatin, was fabricated by electrospinning method, using a new cost-effective solvent mixture: chloroform/methanol for polycaprolactone (PCL) and acetic acid for gelatin. The morphology of the nanofibrous scaffold was investigated by using field emission scanning electron microscopy (FE-SEM) which clearly indicates that the morphology of nanofibers was influenced by the weight ratio of PCL to gelatin in the solution. Uniform fibers were produced only when the weight ratio of PCL/gelatin is sufficiently high (10:1). The scaffold was further characterized by Fourier transform infrared (FT-IR) spectroscopy, thermogravimetric (TG) analysis, and X-ray diffraction (XRD). FT-IR and TG analysis indicated some interactions between PCL and gelatin molecules within the scaffold, while XRD results demonstrated crystalline nature of PCL/gelatin composite scaffold. Cytotoxicity effect of scaffold on L929 mouse fibroblast cells was evaluated by MTT assay and cell proliferation on the scaffold was confirmed by DNA quantification. Positive results of MTT assay and DNA quantification L929 mouse fibroblast cells indicated that the scaffold made from the combination of natural polymer (gelatin) and synthetic polymer (PCL) may serve as a good candidate for tissue engineering applications.     

Fabrication of a super-hydrophobic nanofibrous zinc oxide film surface by electrospinning

We report a new approach for fabricating a super-hydrophobic nanofibrous zinc oxide (ZnO) film surface. The pure poly(vinyl alcohol) (PVA) and composite PVA/ZnO nanofibrous films can be obtained by electrospinning the PVA and PVA/zinc acetate solutions, respectively. After the calcination of composite fibrous films, the inorganic fibrous ZnO films with a reduced fiber diameter were fabricated. The wettability of three kinds of fibrous film surfaces were modified with a simple coating of fluoroalkylsilane (FAS) in hexane. The resultant samples were characterized by field emission scanning electron microscopy (FE-SEM), water contact angle (WCA), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). It was found that the pure PVA fibrous films maintained the super-hydrophilic surface property even after the FAS modification. Additionally, the WCA of composite fibrous films was increased from 105 to 132° with the coating of FAS. Furthermore, the surface property of inorganic ZnO fibrous films was converted from super-hydrophilic (WCA of 0°) to super-hydrophobic (WCA of 165°) after the surface modification with FAS. Observed from XPS data, the hydrophobicity of FAS coated various film surfaces were found to be strongly affected by the ratio of fluoro:oxygen on the film surfaces.     

Fabrication of metal-organic framework-based nanofibrous separator via one-pot electrospinning strategy

Metal-organic framework(MOF)/polymer composites have attracted extensive attention in the recent years.However,it still remains challenging to efficiently and effectively fabricate these composite materials.In this study,we propose a facile one-pot electrospinning strategy for preparation of HKUST-1/polyacrylonitrile(PAN)nanofibrous membranes from a homogeneous stock solution containing HKUST-1 precursors and PAN.MOF crystallization and polymer solidification occur simultaneously during the electrospinning process,thus avoiding the issues of aggregation and troublesome multistep fabrication of the conventional approach.The obtained HKUST-1/PAN electrospun membranes show uniform MOF distribution throughout the nanofibers and yield good mechanical properties.The membranes are used as separators in Li-metal full batteries under harsh testing conditions,using an ultrathin Li-metal anode,a high mass loading cathode,and the HKUST-1/PAN nanofibrous separator.The results demonstrate significantly improved cycling performance(capacity retention of 83.1%after 200 cycles)under a low negative to positive capacity ratio(N/P ratio of 1.86).The improvement can be attributed to an enhanced wettability of the separator towards electrolyte stemmed from the nanofibrous structure,and a uniform lithium ion flux stabilized by the open metal sites of uniformly distributed HKUST-1 particles in the membrane during cycling.     

Fabrication of the silver/polypyrrole/polyacrylonitrile composite nanofibrous mats

The AgNO₃/polyacrylonitrile hybrid nanofibers were prepared by using electrospinning technique, then the hybrid fibers of AgNO₃/polyacrylonitrile were treated with pyrrole in the boiling toluene medium, finally, the silver/polypyrrole/polyacrylonitrile composite fibrous mats were obtained. The scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Raman spectra were used to characterize the obtained silver/polypyrrole/polyacrylonitrile composite fibrous mats. And the results indicated that the morphologies of the composite fibers were influenced by the content of AgNO₃ in the AgNO₃/polyacrylonitrile fibers. The silver/polypyrrole composite dispersed in the fibrous mats exhibited core-shell structure, and the conductivity of the optimum silver/polypyrrole/polyacrylonitrile composite fibrous mats is relatively high.     

Fabrication and characterization of novel biodegradable Zn-Mn-Cu alloys

Zn-Mn-Cu alloys with micro-alloying of Mn and Cu in Zn are developed as potential biodegradable metals. Although the as-cast alloys are very brittle, their ductilities are significantly improved through hot rolling. Among the as-cast and the as-hot-rolled alloys, as-hot-rolled Zn-0.35 Mn-0.41 Cu alloy has the best comprehensive property. It has yield strength of 198.4 ± 6.7 MPa, tensile strength of 292.4 ± 3.4 MPa,elongation of 29.6 ± 3.8% and corrosion rate of 0.050-0.062 mm a~(-1). A new ternary phase is characterized and determined to be MnCuZn18, which is embedded in MnZn13, resulting in a coarse cellular/dendritic MnZn13-MnCuZn18 compound structure in Zn-0.75 Mn-0.40 Cu alloy. Such a coarse compound structure is detrimental for wrought alloy properties, which guides future design of Zn-Mn-Cu based alloys.The preliminary research indicates that Zn-Mn-Cu alloy system is a promising candidate for potential cardiovascular stent applications.     

Lightweight nanofibrous EMI shielding nanowebs prepared by electrospinning and metallization

The metal-deposited poly(vinyl alcohol) (PVA) composite nanofibrous mats were fabricated by electrospinning and metal-deposition methods for electromagnetic interference (EMI) shielding applications. The metal-deposited nanofiber mats prepared with various metals (Cu, Ni, Ag), their different thicknesses, and different metal deposition systems composed of Cu and Ni were used for EMI shielding measurement. For the EMI SE measurement, a near-field antenna measurement system was used. The measurement of EMI SE was carried out at the frequency range from 0.5 to 18 GHz, and the electromagnetic parameters were measured. The experimental results showed that absorption was the major shielding mechanism and reflection was the secondary shielding mechanism. The effect of unique porous structure of the metal-deposited composite nanofibrous mats was also discussed.     

Insoluble synthetic polypeptide mats from aqueous solution by electrospinning

Water-insoluble nanofiber mats of synthetic polypeptides of defined composition have been prepared by a process involving electrospinning from aqueous solution. L-ornithine is a physiological amino acid. Fibers of poly(L-ornithine) (PLO) were produced at feedstock concentrations above 20% w/v. Applied voltage and needle-to-collector distance were crucial for nanofiber formation. Attractive fibers were obtained at 35-40% w/v. Fiber diameter and mat morphology have been characterized by electron microscopy. Polymer cross-linking with glutaraldehyde (GTA) vapor rendered fiber mats water-insoluble. The study has yielded two advances on previous work in the area: avoidance of an animal source of peptides and avoidance of inorganic solvent.     

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.     

含氟聚合物纳米多孔纳米纤维膜的制备

采用"电纺-相分离-沥滤"方法制备了聚(偏氟乙烯-co-六氟丙烯)(PVDF-HFP)以及聚偏氟乙烯(PVDF)纳米多孔纳米纤维膜.首先,将PVDF-HFP或PVDF和致孔剂聚乙烯吡咯烷酮(PVP)混合电纺,得到共混物纳米纤维膜.然后,将纳米纤维膜在水中沥洗出共混物中的PVP,获得纳米多孔纳米纤维膜.用场发射扫描电子显微镜(FESEM)观察水洗前后纤维表面精细结构.结果表明,纳米多孔纳米纤维表面呈多孔结构,孔径数10 nm.PVP的分子量对水洗后纤维表面结构有明显影响.致孔剂含量不同获得的PVDF-HFP纳米多孔纤维膜力学性能相近.     

熔体静电纺聚乳酸纤维膜的制备、表征及细胞毒性评价

调试熔体静电纺聚乳酸(PLA)过程中的电压场和温度场的参数,对不同条件下的纤维膜进行测试,研究电压场与温度场与纤维直径间的关系,并评价熔体静电纺PLA膜的细胞毒性。以聚乳酸(PLA)为原料,采用熔体静电纺丝方法,电压调整在20~26 k V范围,空间温度在10~70℃之间,分别进行熔体纺丝实验,将制得的纤维膜进行细胞毒性评价。熔体静电纺丝PLA纤维的平均直径随电压的升高逐渐增大,当空间温度为50℃时,所得纤维平均直径为最小。细胞活力测试证实熔体静电纺PLA膜无细胞毒性,具有良好的组织工程材料的应用前景。     

电纺丝法制聚合物纳米纤维

主要介绍电纺丝法制聚合物纳米纤维的研究 ,以及所使用电喷雾沉积法 (ESD)装置和工艺及纳米纤维的应用。     

ZnMn2O4微/纳米纤维的制备及其性能的研究

以聚乙烯吡咯烷酮(PVP)为络合剂与醋酸锌〔Zn(CH3COO)2〕和乙酸锰(Mn(CH3COO)2)反应制得前驱体溶液,用静电纺丝法制备了PVP/Zn(CH3COO)2/Mn(CH3COO)2复合纳米纤维,经煅烧得到具有微孔结构的Mn掺杂ZnO微/纳米纤维。对所制备纤维分别采用差热-热重分析(TG-DTA)、红外光谱(IR)、X射线衍射(XRD)、扫描电镜(SEM)等手段进行了表征。结果表明:PVP/Zn(CH3COO)2/Mn(CH3COO)2纤维表面光滑,直径约300～700nm,经煅烧后,可得到Mn掺杂ZnO微/纳米纤维,XRD测试表明煅烧后的无机纳米纤维呈ZnMn2O4晶相。     

Gold nanoparticle/polymer nanofibrous composites by laser ablation and electrospinning

Poly(vinylpyrolidone) (PVP) nanofibers incorporating gold nanoparticles (Au-NPs) were produced in combination with laser ablation and electrospinning techniques. The Au-NPs were directly synthesized in PVP solution by laser ablation and then, the electrospinning of PVP/Au-NPs solution was carried out for obtaining nanofibrous composites. The presence of Au-NPs in the PVP nanofibers was confirmed by SEM, TEM and EDX analyses. The SEM imaging elucidated that the electrospun PVP/Au-NPs nanofibers were bead-free having average fiber diameter of 810 ± 480 nm. The TEM imaging indicated that the Au-NPs were in spherical shape having diameters in the range of 5 to 20 nm and the Au-NPs were more or less dispersed homogeneously in the PVP nanofiber matrix. The FTIR study suggested the presence of molecular interactions between PVP matrix and the Au-NPs in the nanofibrous composites. The UV–Vis measurement confirmed the enhancement of the optical properties of the PVP/Au-NPs nanofibers in the solid state due to the surface plasma resonance effect of Au-NPs.     

Electrospun polyimide/titanium dioxide composite nanofibrous membrane by electrospinning and electrospraying

Fibrous membrane with a fibre diameter of 229 +/- 35 nm was fabricated from polyimide solution by electrospinning. Nanofibrous membrane with a fibre diameter of 251 +/- 37 nm was fabricated by combined electrospinning and electrospraying for polyimide/TiO2. Among the different solvents studied, ethanol was the effective solvent for dispersing the TiO2 nanoparticles in the nanofibrous matrix during electrospraying. The average pore size of polyimide membrane was obtained in the range 0.79-0.89 microm whereas the average pore size of polyimide/TiO2 membrane was found to be in the range 1.23 microm. The tensile stress of polyimide nanofibrous membrane and also polyimide/TiO2 composite fibrous membrane determined to be 0.36 MPa and 0.65 MPa respectively. Nanofibrous membrane containing TiO2 nanoparticles on the surface of the polyimide nanofibres improved the mechanical stability of the membrane.     

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.     

静电纺丝法制备LaMnO3微／纳米纤维

以聚乙烯吡咯烷酮（PVP）为络合剂与Mn（CH3COO）2和La（NO3）3·6H2O反应制得前驱体，用静电纺丝法制备了PVP／Mn（CH3COO）2·La（N03）3纤维，经煅烧得到具有高比表面积的LaMnO3微／纳米纤维。并采用红外光谱（IR）、X射线衍射（XRD）、扫描电镜（SEM）等现代分析手段对所制备的纤维进行了表征。结果表明：焙烧后纤维的直径明显减小，在150-300nm之间：PVP特征吸收峰消失，新生成的M-O吸收峰随着焙烧温度的升高变强；XRD分析出现相应氧化物的特征峰，说明有LaMnO3的生成。     

Fabrication and characterization of curcumin-loaded silk fibroin/P（LLA-CL） nanofibrous scaffold

Curcumin exhibited excellent properties including antioxidant, anti- inflammatory, antiviral, antibacterial, antifungal, anticancer, and anticoagulant activities. In this study, curcumin was incorporated into silk fibroin （SF）/poly（L-lactic acid-co-e- caprolactone） （P（LLA-CL）） nanofibrous scaffolds via electrospinning, and changes brought about by raising the curcumin content were observed： SEM images showed that the average nanofibrous diameter decreased at the beginning and then increased, and the nanofibers became uniform; FTIR showed that the conformation of SF transforming from random coil form to β-sheet structure had not been induced, while SF conformation converted to β-sheet after being treated with 75% ethanol vapor; XRD results confirmed that the crystal structure of （P（LLA-CL）） had been destroyed; The mechanical test illustrated that nanofibrous scaffolds still maintained good mechanical properties. Further, curcumin-loaded nanofibrous scaffolds were evaluated for drug release, antioxidant and antimicrobial activities in vitro. The results showed that curcumin presented a sustained release behavior from nanofibrous scaffolds and maintained its free radical scavenging ability, and such scaffolds could effectively inhibit S. aureus growth （〉 95%）. Thus, curcumin-loaded SF/P（LLA-CL） nanofibrous scaffolds might be potential candidates for wound dressing and tissue engineering scaffolds.