静电纺丝的研究进展

简述了国内外静电纺丝的研究现状;介绍了静电纺丝的制备原理、静电纺丝装置的改进、影响纤维成形的主要工艺参数及纤维形态;叙述了静电纺丝纳米纤维在过滤材料、生物医学和传感器等方面的应用;展望了静电纺丝的发展方向。指出静电纺丝是纳米纤维的新型生产技术,今后应进一步调整静电纺丝工艺,开发绿色溶剂,以尽早实现静电纺丝的工业化。     

明胶静电纺丝的研究进展

作为天然高分子之一的明胶无毒无味,具有优异的生物相容性及生物可降解性。利用静电纺丝技术制备的明胶纳米纤维膜材料能最大程度地仿生天然细胞外基质的胶原蛋白结构,因此在生物医用材料领域具有广泛的应用,引起了国内外学者的普遍关注。本文介绍了明胶静电纺丝装置、工艺的研究进展,同时总结了明胶静电纺丝纳米纤维膜材料在生物医疗领域内的应用研究情况,并展望了明胶静电纺丝工艺与明胶纳米纤维膜材料的发展趋势和研究方向。     

静电纺丝聚合物纳米纤维研究进展

将静电纺丝技术应用到高分子材料研究中,可以制备聚合物纳米纤维,在众多领域有广阔的应用前景。从静电纺丝聚合物纳米纤维原理、有序性、应用的角度,简述其研究进展,并指出一些仍待解决的问题,同时对电纺聚合物纳米纤维未来发展进行了展望。     

静电纺丝接收装置和辅助电极的研究进展

介绍了圆柱状转鼓、凝固池、旋转圆盘框架、相对圆环、平行电极等静电纺丝的接收装置;简述了刀锋型、平行、圆筒型及其改进的静电纺丝辅助电极;分析了接收装置和辅助电极对静电纺丝制备微/纳米纤维外貌观形貌和性能的影响;通过对静电纺丝接收装置的改进和增加辅助电极,可获得不同形态和结构的微/纳米纤维。     

静电纺丝聚合物纤维的研究进展

介绍了静电纺丝法制备聚合物纤维的原理及其影响因素,综述了国内外静电纺丝聚合物纤维的研究进展及其应用状况,指出了静电纺丝聚合物纤维需要解决的若干问题,并对静电纺丝技术的发展进行了展望.     

激光熔体静电纺丝研究进展

简述了静电纺丝法的发展历程及研究概况,比较了溶液静电纺丝法和熔体静电纺丝法的优缺点;详细介绍了激光熔体静电纺丝法的优势,总结了目前激光熔体静电纺丝法制备聚合物及复合物微纳米纤维的工艺条件如激光输出功率、应用电压以及聚合物的物理性质等对纤维直径的影响;简要介绍了线激光熔体静电纺丝装置;指出目前激光熔体静电纺丝法制得的多为...     

静电纺丝的技术进展

简述了静电纺丝的原理、装置及发展历程;比较了溶剂静电纺丝法和熔融静电纺丝法;介绍了静电纺丝法的技术进展。指出在熔融型静电纺丝法的研究中,开发了具有激光加热部的熔融型静电纺丝装置,进一步突破了纳米纤维的制造技术。随着纳米技术的不断发展,静电纺丝法制造的纳米纤维应用广泛,其发展前景看好。     

无针头静电纺丝研究进展

通过介绍无针头溶液静电纺丝和熔体静电纺丝的研究进展,对纺丝装置、纺丝过程和有关结论进行了综述,分析了各种实验方法的特点以及所得纤维的特性,并指出目前存在的问题和需要改进的地方,为无针头静电纺丝的深入研究提供理论依据,同时为静电纺丝纳米纤维的产业化和应用开发奠定基础。     

静电纺丝技术制备催化剂的研究进展

综述了静电纺丝技术制备纳米纤维的3种方法——同轴电纺法、溶胶转化法和功能复合法,分析了3种制备催化剂方法的优缺点,并对静电纺丝技术未来的发展方向进行了展望。     

聚合物离心静电纺丝技术研究进展

简述了离心静电纺丝技术的工作原理,对国内外近期离心静电纺丝的研究进展进行了综述.总结了离心静电纺丝的成纤机理,根据纺丝材料特性,将离心静电纺丝分为溶液离心静电纺丝和熔体离心静电纺丝两类,并将这两类纺丝方法的装置和工艺创新进行了分类,总结了各种装置的结构特征和优缺点,并对其工艺参数进行了分析.最后对离心静电纺丝微纳米纤维...     

Upward needleless electrospinning of multiple nanofibers

A new approach to electrospinning of polymer nanofibers is proposed. A two-layer system, with the lower layer being a ferromagnetic suspension and the upper layer a polymer solution, is subject to a normal magnetic field provided by a permanent magnet or a coil. As a result, steady vertical spikes of magnetic suspension perturbed the interlayer interface, as well as the free surface of the uppermost polymer layer. When a normal electric field is applied in addition to the system, the perturbations of the free surface become sites of jetting directed upward. Multiple electrified jets undergo strong stretching by the electric field and bending instability, solvent evaporates and solidified nanofibers deposit on the upper counter-electrode, as in an ordinary electrospinning process. However, the production rate is shown to be higher.     

Buckling of jets in electrospinning

Various buckling instabilities of electrospinning jets were observed and compared with the buckling instabilities of uncharged fluid jets. Buckling instability arises due to jet compression at impingement on a collector surface and occurs independently of the electrical bending instability. The velocity, diameter, density and viscosity of the electrospinning jets are the key factors that determine the buckling frequency. The electrically charged jets impinging onto grounded, horizontal or inclined (wedge-like) electrodes moving laterally at a constant velocity are studied experimentally. Straight and bending (electrospinning) jets emerge at short and sufficiently long inter-electrode distances, respectively. The experiments show that both straight segment and bending jets, when impinging onto a counter-electrode, buckled and produced patterns of meandering deposits. In the case of bending electrospun jets these short-length buckling patterns were superimposed on the bending loops found in the deposits. Buckling-related and bending-related morphologies are easily distinguishable. The buckling patterns have frequencies of the order of 10⁵-10⁶ Hz, whereas the bending loops are formed at the frequencies of the order of 10³ Hz. The deposited buckling patterns include sinuous, zigzag-like, figures-of-eight, recurring curves, coiled and other structures that resembled many patterns created by uncharged jets of highly viscous fluids impinging a hard flat surface. In addition, several new morphologies which were not observed before with uncharged jets were found. The experimentally measured frequencies of the buckling patterns were compared to the theoretical predictions and a reasonable agreement was found.     

Continuous aligned polymer fibers produced by a modified electrospinning method

A novel and simple technique of manufacturing uniaxially aligned electrospun fibers with diameter of sub-micrometers is described. Compared with typical electrospinning setup, two oppositely placed metallic needles are used, and they are connected to positive and negative voltages, respectively. Fibers coming out of the two needles combine in a yarn, which is wound by a cylinder collector rotating at a high speed. Fibers manufactured by this method are continuous, well-aligned, and can be deposited over a large area. Poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) are used to manufacture aligned fibers. An analysis of the possible mechanism of the fibers alignment is given. The influences of the concentration of the solution and the take-up velocity on the alignment of fibers were investigated.     

Scaling law on particle-to-fiber formation during electrospinning

The development of various morphologies such as beads, beaded fibers, pure fibers and their scaling as a function of solution properties and processing variables in electrospinning is reported. Polyvinyl pyrrolidone (PVP), at various molecular weights and concentrations dissolved in a mixture of water and ethanol, was used to prepare different morphologies and sizes. The morphology of beads and fibers was predicted and measured based on an entanglement number diagram and rheological measurements. A constant-current electrospinning system was employed to control the processing variables. Scaling laws related to solution properties and processing variables (voltage, current and flow rate), and their effect on the fiber/bead diameter, were discussed. Viscosity (η), flow rate (Q), and current (I) were found to play significant roles in the control of morphology during electrospinning. Processing variables involved in electrospinning followed a power scaling that was in agreement with the model. The dependence of fiber diameter (d_f) on the Q/I for different molecular weights and concentrations also followed a power law, and the scaling varied between 0.11-0.29 for beaded fiber and 0.36-0.51 for pure fiber. In addition, the relationship between viscosity and fiber diameter followed scaling laws: d_f ∼ η^0.98.     

Synthesis, characterization, and electrospinning of zwitterionic poly(sulfobetaine methacrylate)

Poly(sulfobetaine methacrylate) (PSBMA) can be potentially utilized in filtration and wound dressing applications for which nanofibers structures are highly desirable. In this work, a series of PSBMAs with different molecular weights were synthesized, characterized, and electrospun into nanofibers. The polymer molecular weight was controlled by varying the amount of redox initiators in the free radical polymerization of SBMA, with the highest molecular weight achieved at an intermediate initiator concentration. From the intrinsic viscosity measurements, the Mark-Houwink parameters for PSBMA (at 21 °C in 0.2 M NaCl solution) was determined as a = 0.4071 and k = 2.06 × 10⁻³. Thermogravimetric (TGA) analysis shows that the PSBMAs were thermally stable up to at least 250 °C. Fourier transform infrared (FTIR) spectra indicate major structural changes of both polymer backbone and pendant groups by thermal degradation. Results from differential scanning calorimetry (DSC), TGA, and FTIR characterizations all demonstrate the existence of water strongly bound in PSBMA. DSC analysis also indicates different degrees of crystallinity for the PSBMAs of different sizes. Viscosity of the PSBMA solutions, a critical parameter for electrospinning, increased with the solution concentration and the polymer molecular weight. For the electrospinning of PSBMA, it was found that high solution concentration and high molecular weight favored the formation of smooth fibers while low solution concentration or low molecular weight led to the formation of beaded fibers or beads. Fiber diameters ranging from 200 to 570 nm were achieved by controlling solution concentration and polymer molecular weight. The characterization data and electrospinning results were finally correlated to explore the relationships between fiber formation, viscosity, molecular weight, and concentration.     

Preparation of water-stable submicron fibers from aqueous latex dispersion of water-insoluble polymers by electrospinning

Submicron polystyrene (PS) fibers were prepared by electrospinning of an aqueous dispersion of PS latex and a small amount of poly(vinyl alcohol) (PVA) and subsequent extraction by water. Depending on particle size, surfactant, ratio of PS:PVA, and applied voltage fibers of different morphology and water stability were obtained. Analysis of latex fibers by TEM revealed hexagonal packaging of particles within the fibers.     

Characterization on oxidative stabilization of polyacrylonitrile nanofibers prepared by electrospinning

Ultrafine polyacrylonitrile (PAN) fibers, as a precursor of carbon nanofibers, with diameters in the range of 220–760 nm were obtained by electrospinning of PAN solution using N,N-dimethyl formamide (DMF) as solvent. Morphology of the nanofibers for varying concentration and applied voltage was investigated by field emission scanning electron microscopy (FESEM). The thermal properties and structural changes during the oxidative stabilization process were primarily investigated by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared (FT-IR) and Raman spectroscopy. The nanofiber diameters increase as the applied voltage is increased and they also increase with an increase in the concentration of the polymer solution. It was also concluded that the electrospun fibers displayed a very sharp exothermic peak at 297.34 °C. A transition temperature observed by FT-IR and Raman was approximately 300 °C, which was closely consistent with the results of DSC and TGA studies. It was also found that oxidative stabilization in air was accompanied by a change in color of nanofibers webs.     

Ultra-fine polyelectrolyte fibers from electrospinning of poly(acrylic acid)

Ultra-fine polyelectrolyte fibers have been generated from electrospinning of poly(acrylic acid) in aqueous and DMF solutions. The fiber diameters ranged from 80 to 500 nm and increased with increasing solution concentrations and electrospinning voltages. The fibers generated from the aqueous solutions were more homogeneous in sizes, especially when NaCl or NaOH was added. Higher voltages in electrospinning of the aqueous solutions also resulted in fibers with larger heat capacity in the glass transition region, and higher dehydration temperatures. These polyelectrolyte fibers could be rendered water-insoluble by incorporating β-cyclodextrin (at 20 wt% of PAA) in the aqueous solution, then heat-induced crosslinking was performed at 140 °C for 20 min. The resulting hydrogel fibers showed strongly pH-responsive swelling behaviors.     

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.