Electrospinning of collagen-chitosan complex

The collagen-chitosan complex nanofibers have been prepared for the first time by electrospinning. The mixed HFP/TFA (the volume ratio of 90/10) was found to be the appropriate solvent for electrospinning. The concentration of the spinning solution and the ratio of chitosan/collagen were varied and adjusted to get smooth nanofibers. It was found that the diameter of the spun fibers became thick with the concentration of the solution increasing and became fine with the ratio of the chitosan/collagen increasing. We have characterised the molecular interactions in collagen-chitosan complex by Fourier transform infrared spectroscopy. The spun fibers are designed to mimic the native extracellular matrix for tissue engineering and to develop functional biomaterials.     

Electrospinning hollow and core/sheath nanofibers using hydrodynamic fluid focusing

Hollow poly (vinylpyrrolidone) (PVP) + TiO₂ and polypyrrole (core)/PVP (sheath) nanofibers were successfully electrospun using hydrodynamic fluid focusing. Utilizing a two-dimensional fluid focusing technique previously applied to aqueous solutions, intersecting microchannels cast in (poly)dimethylsiloxane were utilized to dynamically center core fluids in immiscible sheath fluids prior to electrospinning at the channel outlet. Advantages of using microfluidic channel networks for the electrospinning of composite nanofibers include spatiotemporal control over input reagents, ease of fabrication and the ability to focus the core stream into sheath layer without the need of complex co-annular nozzles.     

Toward optimizing synthesis of nanostructured chiral polyaniline

We report here detailed investigation into optimizing the synthesis of chiral polyaniline nanofibers using an oligomer-assisted route. The effect of temperature, monomer concentration, nature of oligomer, and the rate of oxidant addition on the optical properties of the PANI nanofibers have been carefully determined. Our results indicate that the highest chirality is achieved under conditions that promote interaction of the chiral acid with the growing polymer chain. These chiral polyaniline nanofibers are thermally stable up to 90 °C and are found to be stable against repeated doping-dedoping cycles. The as-synthesized nanofibers are partially crystalline regardless of their chirality. This partial crystallinity may be responsible for their chemical and thermal stability.     

Photoluminescent properties of Eu3+ doped electrospun CeO2 nanofibers

In this study, CeO₂ nanofibers and that doped with Eu³⁺ were prepared via a facile electrospinning route and annealed at different temperatures ranging from 500 to 900 °C. Their structures were investigated using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Photoluminescence properties of the nanofibers were studied in detail. It was found that the nanofibers with Eu% concentration of 0.67 mol.% and annealed at 700 °C exhibited the highest intensities of the luminescence peaks between 550 and 650 nm.     

Preparation of PVDF/PVP core–shell nanofibers mats via homogeneous electrospinning

The polyvinylpyrrolidone (PVP)/poly(vinylidene fluoride) (PVDF) core–shell nanofiber mats with superhydrophobic surface have been prepared via electrospinning its homogeneous blending solutions, and the formation of the core–shell structure was achieved by the thermal induced phase separation assisted with the low surface tension of PVDF. The electrospinnability of the blending solutions was also investigated by varying the blending ratio of the PVP and PVDF, and it enhanced with the increase of PVP content. SEM and TEM results showed that the fibers size was varied in the range of 100 nm–600 nm with smooth surface and core–shell structure. The composition of the shell layer was determined by the XPS analysis, and further confirmed by water contact angle (WCA) testing. As the fraction of PVDF exceeding PVP in the electrospinning solutions, the nanofiber mats showed superhydrophobic property with the WCA above 120°. It indicated that the PVDF was concentrated in the shell layer of the fibers. X-Ray diffraction (XRD) and attenuated total reflection infrared spectroscopy (ATR-IR) analysis indicated that the PVDF was aggregated with the β-phase crystallite as dominant crystallite. The nanofiber mats with the gas breathability and watertightness ability due to the porous structure and superhydrophobic would be potential applied in wound healing.     

Carbon induced phase transformation in electrospun TiO2/multiwall carbon nanotube nanofibers

Nanofibers of titania and composite nanofibers of titania and multiwall carbon nanotubes were synthesized by electrospinning using a sol-gel process combined with activated carbon nanotubes. The relationships of treatment temperature, carbon nanotube content on the crystal phase, fiber morphology, and electric properties are reported. It is found that the rutile phase becomes more prominent at low heat treatment temperatures with an increase of carbon content in nanofibers, be it for higher amount of carbon due to reducing atmosphere or due to an increase in MWCNT. Atmospheric control and lower heat treatment temperatures enable crystalline nanocomposite fibers of anatase where the level of rutile is below the detection limit of XRD or Raman spectroscopy. This work provides a new path to fabricate electrospun TiO₂/MWCNT nanocomposite nanofibers with limited C-induced rutile phase.     

静电纺丝制备PVDF多孔纳米纤维及其在吸油中的应用

采用静电纺丝和PEO模板相结合加工制备了具有超疏水性能的PVDF多孔纳米纤维.通过扫描电镜(SEM)观察所制备的PVDF纤维具有均匀微纳米二级孔道显微结构,测得该多孔纳米纤维表面接触角高达158°,呈现良好的超疏水特性.研究发现,将PVDF多孔纳米纤维作为溢油吸附材料具有良好的吸油效能,其对润滑油、柴油、植物油和汽油的...     

A New Image Analysis Based Method for Measuring Electrospun Nanofiber Diameter

In this paper, a new image analysis based method for electrospun nanofiber diameter measurement has been presented. The method was tested by a simulated image with known characteristics and a real web. Mean (M) and standard deviation (STD) of fiber diameter obtained using this method for the simulated image were 15.02 and 4.80 pixels respectively, compared to the true values of 15.35 and 4.47 pixels. For the real web, applying the method resulted in M and STD of 324 and 50.4 nm which are extremely close to the values of 319 and 42 nm obtained using manual method. The results show that this approach is successful in making fast, accurate automated measurements of electrospun fiber diameters.     

PIPD/Cu2 纳米纤维气凝胶的制备及性能

以聚(2,5-二羟基-1,4-苯撑吡啶并二咪唑)(PIPD)为基体、三氟乙酸(TFA)和甲烷磺酸(MSA)为混酸,通过混酸剥离-去质子化诱导凝胶-冷冻干燥-惰性气氛高温处理制备出PIPD纳米纤维气凝胶.对PIPD纳米纤维气凝胶的形貌和结构进行表征,结果表明,混酸法制备PIPD纳米纤维气凝胶过程中,强质子酸破环了PIPD纤维的晶区和取向,PIPD主体的化学结构未发生明显变化.制得的PIPD纳米纤维气凝胶具有蜂窝孔结构、低密度(6.90～15.2 mg/cm3)和高孔隙率(99.1％～99.6％).当PIPD含量(以MSA和TFA总质量为基准,下同)不高于1％时,PIPD纳米纤维气凝胶无明显收缩.惰性氛围高温处理使PIPD纳米纤维气凝胶具有弹性.水平垂直燃烧、极限氧指数(LOI)、导热系数测试表明,PIPD含量为0.5％的纳米纤维气凝胶达到不可燃水平(UL-94,V-0级),LOI高达49.2％,100℃下低热传导性〔导热系数为0.052 W/(m·K)〕.此外,引入Cu2+配位交联网络提高PIPD纳米纤维气凝胶的压缩应力,增强后气凝胶的压缩应力是初始PIPD纳米纤维气凝胶的约16倍.