Step Electrospinning Research Articles

Electrospun Mutualism–Inspired CA/CMA/PHMB ultrafine bimodal nanofibrous membrane for High–Performance, Antibacterial, and Mosquito–Repellent air filtration

Composite bio–based multifunctional air filtration is a great challenge and development trend for personal protection. This work was inspired by nature mutualism to produce bio–based and essential oil loaded nanofibrous membrane with multiple functions of high–performance, antibacterial, and mosquito–repellent. The cinnamaldehyde (CMA) and poly(hexamethylene biguanide) (PHMB) were introduced into the cellulose acetate (CA) polymer system to achieve functionalization, and then the CA/CMA/PHMB ultrafine bimodal nanofibrous membrane was prepared through one–step electrospinning. Compared to eugenol, the CMA contributed to the refinement of fiber and minimized the reduction of mechanical properties, thermal stability, and hydrophobicity. On the other hand, the PHMB enhanced jet splitting and synergistically improved antibacterial ability with CMA. The filtration efficiency for PM0.3, the pressure drop, and the quality factor were 99.78%, 59.5 Pa, and 0.1028 Pa−1, respectively. The bacteriostatic rates against Escherichia coli and Staphylococcus aureus, and the mosquito–repellent rate were 99.65%, 99.99%, and 92.7%, respectively. Lastly, the batch preparation of this solution was explored, which contributed to commercialization. This work provides a novel and simple approach to efficiently fabricate multifunctional high–performance air filter, which will promote the development of bio–based and sustainable air filter.

In situ growth of CsPbBr3@PS flexible fiber papers by one step electrospinning with high stability toward fluorescent sensor

Recently, all-inorganic CsPbX3 (Br, I, CI) perovskites are hot and potential materials which apply to photoelectric device, due to their excellent photoelectric properties such as high carrier mobility, high fluorescence, etc. However, the poor stability greatly restricts their practical applications. In this paper, CsPbBr3 nanocrystals (NCs) were in-situ encapsulated into PS polymer nanofibers by one step electrospinning with highly uniform size and spatial distribution. The hydrothermal stability of the obtained CsPbBr3@PS flexible fiber paper was radically improved with a photoluminescence quantum yield (PLQY) of 66.3%. The PL strength remained 97.2% of the initial value after immersion in water for 10 days. Their PLQY remains above 50% of its original value after heating at 80 °C for 5 h. Due to the excellent optical properties and stability of CsPbBr3@PS flexible fiber papers, the detection for rhodamine 6G (R6G) and rhodamine B (RhB) aqueous solution with high FRET value of 24.7% and 21.4%, respectively. Moreover, the minimum detection limit for R6G aqueous solution is 0.005 ppm. This study suggests that the CsPbBr3@PS flexible fiber paper is a good candidate for fabricating flexible optoelectronic devices, promising application potentials in lighting and display fields.

Preparation, Characterization, and Antioxidant Activity of L-Ascorbic Acid/HP-β-Cyclodextrin Inclusion Complex-Incorporated Electrospun Nanofibers

L-Ascorbic acid (LAA) is a key vitamin, implicated in a variety of physiological processes in humans. Due to its free radical scavenging activity, it is extensively employed as an excipient in pharmaceutical products and food supplements. However, its application is greatly impeded by poor thermal and aqueous stability. Herein, to improve the stability and inhibit oxidative degradation, we prepared LAA-cyclodextrin inclusion complex-incorporated nanofibers (NFs). The continuous variation method (Job plot) demonstrated that LAA forms inclusions with hydroxypropyl-β-cyclodextrin (HP-β-CD) at a 2:1 molar stoichiometric ratio. The NFs were prepared via the single step electrospinning technique, without using any polymer matrix. The solid-state characterizations of LAA/HP-β-CD-NF via powder x-ray diffractometry (PXRD), Fourier-transform infrared (FT-IR) analysis, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and nuclear magnetic resonance (1H NMR and 2D-NOESY) spectroscopy, reveal the effective encapsulation of the LAA (guest molecule) inside the HP-β-CD (host) cavity. The SEM micrograph reveals an average fiber diameter of ~339 nm. The outcomes of the thermal investigations demonstrated that encapsulation of LAA within HP-β-CD cavities provides improved thermal stability of LAA (by increasing the thermal degradation temperature). The radical scavenging assay demonstrated the enhanced antioxidant potential of LAA/HP-β-CD-NF, as compared to native LAA. Overall, the study shows that cyclodextrin inclusion complex-incorporated NFs, are an effective approach for improving the limitations associated with LAA, and provide promising avenues in its therapeutic and food applications.

Direct Fabrication of Functional Shapes on 3D Surfaces Using Electrospinning.

In this work, we demonstrate the ability to simultaneously pattern fibers and fabricate functional 2D and 3D shapes (e.g., letters, mask-like structures with nose bridges and ear loops, aprons, hoods) using a single step electrospinning process. Using 2D and 3D mesh templates, electrospun fibers were preferentially attracted to the metal protrusions relative to the voids so that the pattern of the electrospun mat mimicked the woven mesh macroscopically. On a microscopic scale, the electrostatic lensing effect decreased fiber diameter and narrowed the fiber size distribution, e.g., the coefficient of variation of the fiber diameter for sample collected on a 0.6 mm mesh was 14% compared to 55% for the sample collected on foil). Functionally, the mesh did not affect the wettability of the fiber mats. Notably, the fiber patterning increased the rigidity of the fiber mat. There was a 2-fold increase in flexural rigidity using the 0.6 mm mesh compared to the sample collected on foil. Overall, we anticipate this approach will be a versatile tool for design and fabrication of 2D and 3D patterns with potential applications in personalized wound care and surgical meshes.

Electrospun Fe3O4-PVDF Nanofiber Composite Mats for Cryogenic Magnetic Sensor Applications

Magnetically responsive, mechanically stable and highly flexible iron (III) oxide-polyvinylidene fluoride (Fe3O4-PVDF) piezoelectric composite fiber mats were fabricated via one step electrospinning method for magnetic sensing at cryogenic temperature. The properties of Fe3O4-PVDF composite fiber mats were characterized using scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, d33 and magnetization test. The fiber diameter decreased as the concentration of Fe3O4 increased. The DSC results suggested a decrease in the crystallinity of the composite fiber mats after adding Fe3O4, and the XRD curves identified that the decrease in crystallinity took place in the β crystalline phases of the fibers. FT-IR results further confirmed the reduction of β phases of the composite fiber mats which dropped the piezoelectric response of the fiber mats by 38% for 5% Fe3O4-PVDF than PVDF fiber but still 400% higher than PVDF pellets. The magnetization test advocated a superparamagnetic state of the fiber at room temperature but a ferromagnetic behavior at a lower temperature. The coercivity values of the mats suggested a homogeneous dispersion of the Fe3O4 nanoparticles into the PVDF matrix. Young’s modulus (E) of the fibers remained the same before and after the magnetization test, indicating the mechanical stability of the fiber in the range of 5 K to 300 K. Its mechanical stability, superparamagnetic behavior at room temperature and ferromagnetic at low temperature could open up its application in spintronic devices at cryogenic temperature and cryogenic power electronic devices.

Fabrication of superhydrophobic and self cleaningPVA‐silicafiber coating on304L SSsurfaces by electrospinning

AbstractIn this work superhydrophobic coating with self cleaning property is fabricated on 304L SS samples directly using a simple one step electrospinning process followed by silane treatment by using polyvinyl alcohol (PVA) and tetraethyl orthosilicate solution. A maximum water contact angle of 169.2° ± 2.1° is obtained at an electrospinning potential of 15 kV for 2 h, with a distance of 18 cm between the collector and needle. The hierarchical nanostructures thus formed on 304L SS composed of poly(vinyl alcohol)‐silica microbeads and nanofibers. The surface morphologies are optimized by varying the electrospinning voltage, time, distance between needle and the collector and aging duration of the precursors. Attenuated total reflectance‐infrared spectroscopy studies at different stages of preparation confirmed the presence of PVA/SiO2composite nanofibers deposited on the 304L SS surface. The reaction of SiO2nanofibers with hexamethyl disilazane resulted in the formation of SiOSi bonds that provided water repellent property. The developed SHP surface coating on 304L SS sample showed dynamic bouncing of water droplets and excellent self cleaning performance. The sample retained the SHP behavior in chloride solutions with different ionic strengths and pH.

Micropatterning and Integration of Electrospun PVDF Membrane Into Microdevice

This article reports a novel work on the fabrication of microarrays of electrospun Poly(vinylidene fluoride) (PVDF) membrane for MEMS and energy harvesting applications. Micropatterning of PVDF membrane is an essential step in fabrication process in order for the sample to be integrated in microelectromechanical systems. The high $\beta $ -phase fraction of PVDF membranes was successfully synthesized by one step electrospinning technique. A new fabrication process for micropatterning of electrospun PVDF membrane is being proposed using dry reactive ion etching. Oxygen plasma was chosen as the feeding gas in investigation for high etching rate in PVDF microstructure fabrication process. Micropatterning dimensions of 200/500/ $200~\mu \text{m}$ with the height of over $50~\mu \text{m}$ and etching rate of $2~\mu \text{m}$ /min were achieved in this work. Details of the fabrication process are discussed. High etching rate of patterning process with the selected parameters can be achieved on the electrospun PVDF membranes. This work has demonstrated successful micropatterning and integration of PVDF membrane into MEMS, thus open the possibilities for various application such as for sensors and actuators utilizing polymer membrane. We have validated the capability of the micropatterned device as energy harvester in producing an open circuit voltage density of 1.42 $\text{V}\cdot \text{m}^{{-2}}$ at temperature of 310.15 K and wind speed of 1 $\text{m}\cdot \text{s}^{{-1}}$ . [2019-0180]

Ba0.5Sr0.5Co0.8Fe0.2O3-δ / Gd0.1Ce0.9O2-δ Core/shell Nanofiber Via One-Step Electrospinning for Cathode of LT-SOFCs

The cathode of solid oxide fuel cells (SOFC) is highly related with reduction of oxygen which is the critical factor for whole performance. In order to exert high power, research for improving the cathode property is essential. Enhancing the performance by modifying the nanostructure of cathode has limitation such as collapse of structure during the ceramic process at high temperature. In this study, Gd0.1Ce0.9O2-δ (GDC) embedded Ba0.5Sr0.5Co0.8Fe0.2O3- δ (BSCF) nanofiber which has advantages such as charge transfer, large reaction site was investigated for cathode SOFC. One step electrospinning for synthesizing heterogeneous nanofiber was employed with solution contains BSCF particles and Gd(NO3)3 ,Ce(NO3)3 in dimethylformamide(DMF). GDC nanoparticles which has diameter of 50-100nm are embedded on the surface of BSCF nanofiber which has diameter of 400nm after sintering at 1000 oC. Ideal structure for cathode which facilitates efficient path for electron and ion was fabricated.

Ba0.5Sr0.5Co0.8Fe0.2O3-δ / Gd0.1Ce0.9O2-δ Core/shell Nanofiber Via One-Step Electrospinning for Cathode of LT-SOFCs

The cathode of solid oxide fuel cells (SOFC) is highly related with reduction of oxygen which is the critical factor for whole performance. In order to exert high power, research for improving the cathode property is needed. And reducing the expensive, complicate process is essential for accepting SOFC as future energy source. In this study, Ba0.5Sr0.5Co0.8Fe0.2O3-δ (BSCF)/Gd0.1Ce0.9O2-δ (GDC) core/shell nanofiber which has advantages such as charge transfer, large reaction site was investigated for cathode SOFC. One step electrospinning for synthesizing heterogeneous nanofiber was employed with solution contains BSCF particles and Gd(NO3)3, Ce(NO3)3 indimethylformamide(DMF). Porous GDC shell surrounds the surface of BSCF nanofiber which has diameter of 200nm after sintering at 600 oC. Ideal structure for cathode which facilitates efficient path for electron and ion was fabricated.

Effect of polymer and ceramic morphology on the material and electrochemical properties of electrospun PAN/polymer derived ceramic composite nanofiber membranes for lithium ion battery separators

Electrospun polyacrylonitrile (PAN)/ceramic fibers were created by combining the PAN polymer and various room temperature curable organopolysilazane (OPSZ) precursors in a one step electrospinning process. The resultant PAN/ceramic (70:30wt%) hybrid fiber mats consisted of well-formed, uniform fibers with evenly distributed ceramic, both in the longitudinal and cross-sections of the fibers. The presence of the tetraethyl orthosilicate (TEOS) pendant chain attached to the polysilazane (PSZ) backbone impacted the ability of the ceramic to form a continuous ceramic network within the polymer network. Results show that the membranes with an interconnected ceramic domain showed superior mechanical and electrochemical properties. The interconnected ceramic domains affect the polymer's ability to crystallize, leading to an increase in amorphous regions within the fiber. The increase in amorphous regions leads to increased electrolyte uptake, superior ionic conductivity and excellent cycling performance. Batteries containing 40wt% TEOS:PSZ and 20wt% TEOS:PSZ separators showed greater than 90% capacity retention at a C/5 discharge rates after 100 cycles. C-rate tests show a similar trend with 40wt% TEOS:PSZ and 20wt% TEOS:PSZ membranes maintaining greater capacity retention even at high charge rates.

A one step electrospinning process for the preparation of polyaniline modified TiO2/polyacrylonitile nanocomposite with enhanced photocatalytic activity

A one step electrospinning approach was utilized for the preparation of polyaniline (PANI) modified titanium dioxide/polyacrylonitrile (PAN) composite nanofiber using a mixture of dimethylformamde (DMF) and N-methyl-2-pyrrolidone (NMP) as solvents. Several techniques were carried out to characterize the resulting electrospun fibers including SEM, FTIR, XRD, TGA and DRUV-Vis absorption spectroscopy. The later method showed an optical band gap shifting for polyaniline modified titanium dioxide/polyacrylonitrile composites in comparison to unmodified one. Due to these optical absorptions, the fibers can be considered promising candidates as visible light photocatalysts to generate more electron-hole pairs. Photodegradation was accomplished using methyl orange (MO) as a model organic pollutant. The degradation of MO, extremely increased using photocatalysts which contained PANI and decolorization in the presence of visible light achieved up to 90% in less than 60 min in comparison with the neat nanofibers (about 10%). This advantage promises a bright future for these fibers as useful photocatalysts.The effect of reaction parameters such as photocatalyst dose, concentration of the starting substrate solution and pH were studied and photocatalytic kinetics was investigated. The stability of photocatalyst was also investigated. The photocatalyst retained 87% of its initial activity after 10 replicate uses.

Supercapacitor Electrodes Based on High-Purity Electrospun Polyaniline and Polyaniline-Carbon Nanotube Nanofibers.

Freestanding, binder-free supercapacitor electrodes based on high-purity polyaniline (PANI) nanofibers were fabricated via a single step electrospinning process. The successful electrospinning of nanofibers with an unprecedentedly high composition of PANI (93 wt %) was made possible due to blending ultrahigh molecular weight poly(ethylene oxide) (PEO) with PANI in solution to impart adequate chain entanglements, a critical requirement for electrospinning. To further enhance the conductivity and stability of the electrodes, a small concentration of carbon nanotubes (CNTs) was added to the PANI/PEO solution prior to electrospinning to generate PANI/CNT/PEO nanofibers (12 wt % CNTs). Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) porosimetry were conducted to characterize the external morphology of the nanofibers. The electrospun nanofibers were further probed by transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR). The electroactivity of the freestanding PANI and PANI/CNT nanofiber electrodes was examined using cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy. Competitive specific capacitances of 308 and 385 F g(-1) were achieved for PANI and PANI-CNT based electrodes, respectively, at a current density of 0.5 A g(-1). Moreover, specific capacitance retentions of 70 and 81.4% were observed for PANI and PANI-CNT based electrodes, respectively, after 1000 cycles. The promising electrochemical performance of the fabricated electrodes, we believe, stems from the porous 3-D electrode structure characteristic of the nonwoven interconnected nanostructures. The interconnected nanofiber network facilitates efficient electron conduction while the inter- and intrafiber porosity enable excellent electrolyte penetration within the polymer matrix, allowing fast ion transport to the active sites.

Cu0-decorated, carbon-doped rutile TiO2 nanofibers via one step electrospinning: Effective photocatalyst for azo dyes degradation under solar light

In this study, zero valent copper nanoparticles (Cu0 NPs)-decorated, carbon-doped titania nanofibers were successfully prepared by electrospinning of a solution composed of titanium isopropoxide (TIP), polyvinylpyrroliodine (PVP), and copper(II) acetate tetrahydrate. The calcination of the formed nanofiber mats in Ar atmosphere at 850°C led to produce good morphology nanofibers. The produced powder was characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and field-emission scanning electron microscopy (FESEM). Characterization techniques indicated that the obtained material is Cu0 NPs-decorated, carbon-doped TiO2 nanofibers. The synthesized nanofibers were used as photocatalyst for the effective degradation of reactive black 5 (RB5) and methyl red (MR) azo dyes in aqueous solution. The introduced nanofibers showed good photodegradation activity under sunlight. Overall, introduced nanofibers revealed a better photocatalytic activity when compared to pristine TiO2 nanofibers. The better performance was due to the removal of RB5 and MR at 83% and 65%, respectively. This study opens a new avenue to produce transition metal-decorated, carbon-doped titania nanofibers in a single production step for the use in different catalytic reactions.

Efficiency enhancement of ZnO-based dye-sensitized solar cell by hollow TiO2 nanofibers

One-dimensional nanostructures as the photoanode of dye-sensitized solar cell (DSSC) can provide a direct transport pathway for electrons injection to increase electrons transfer efficiency. In this work, hollow TiO2 nanofibers were fabricated by one step electrospinning based on sol–gel method, and were used to successfully enhance the conversion efficiency of ZnO-based DSSC. The effects of different TiO2 weight percentages on the performance of TiO2/ZnO composite photoanode were investigated systematically. The results indicate that the light scattering of the photoanode film is increased and the electrons recombination is suppressed when appropriate amount of hollow TiO2 nanofibers was added into ZnO. The maximal energy conversion efficiency reaches 4.59% by adding 10wt.% of hollow TiO2 nanofibers, which is 62% higher than that of DSSC based on pure ZnO nanoparticles.

Molecular weight driven structure formation of PEG based e-spun polymer blend fibres

Electrostatic spinning of polymer blends offers the potential to obtain functionalised nano- to micron-scaled fibres which combine the properties of the blend components. In tissue engineering for instance, the surface chemistry incorporates, besides mechanical and morphological properties, a key role for enhanced cell proliferation and differentiation. Therefore we developed porous fibre non-wovens with tuneable wettability properties by use of a one step electrospinning procedure and the use of polymer blends with defined molecular weight (MW) ratios.Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDFhfp) and poly(ethylene glycol) (PEG) were mixed with constant weight ratios but varying PEG MW's. Electrostatic spinning of these solutions reveals fibre morphologies with increasing diameters in function of the MW. By addition of small amounts of nanosized TiO2 particles stable fibre diameter were found due to an increase of the electrical conductivity of the spinning dispersions. Interestingly, polymer MW has a great impact on fibre structure and surface chemical composition, respectively. High surface concentrations of oxygen and thus PEG within the sheath are found for high MW's, whereas most of the low MW PEG is located within the fibre core. It is suggested, that polymer molecular chain mobility as well as polymer solubilities are the key factors influencing the mechanism of fibre formation and thus the final distribution and morphology of the polymers within the fibres. These results are underpinned by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), static water contact angles and rheological measurements.

Pure Chitosan and Chitsoan/Chitosan Lactate Blended Nanofibres made by Single Step Electrospinning

Abstract A single step electrospinning of chitosan and chitosan derivative-chitosan lactate nanofibres was studied in this paper. Chitosan was dissolved into acetic acid to produce structure-stable nanofibres. The effect of chitosan concentration and the content of acetic acid on the fibre diameter and morphology of nanofibres were studied in detail. The dynamic viscosity and surface tension of the electrospinning chitosan solutions were systematically studied as well. Based on the fundamental study on electrospinning chitosan in acetic acid, a chitosan derivative, chitosan lactate, was added to produce nanofibre in a pH-friendly aqueous environment. Chemical and morphological analyses demonstrated that chitosan lactate will positively influence the formation of nanofibres in higher pH condition although the morphology should be improved.

Preparation of Solid and Hollow Asphaltene Fibers by Single Step Electrospinning

Electrospinning has been used to produce micrometer size fibers, both solid and hollow from non-covalently associating small molecules of a low grade hydrocarbon reject of crude oil, asphaltene. Asphaltene defined as a solubility class of crude oil is by no means a polymer but relatively large organic molecule of molecular weight ranging from 500 to 1000 Dalton. The production of asphaltene fibers is feasible by electrospinning because of its unique molecular structure which allows molecular aggregation. Fibers with diameter ranging from 2–20 μm were successfully spun from an asphaltene in toluene solution. Adding 2% hydrogen peroxide enhances electrospinning, leading to formation of hollow fibers, whereas adding 2% water inhibits electrospinning. The structure and morphology of the electrospun fibers were investigated with optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectroscopy. The electrospun asphaltene fibers offer the potential for direct fabrication of membranes without use of multiple synthetic steps, complex electrospinning designs, or post processing surface treatments.

Fabrication of chitosan/poly(caprolactone) nanofibrous scaffold for bone and skin tissue engineering

Chitosan/poly(caprolactone) (CS/PCL) nanofibrous scaffold was prepared by a single step electrospinning technique. The presence of CS in CS/PCL scaffold aided a significant improvement in the hydrophilicity of the scaffold as confirmed by a decrease in contact angle, which thereby enhanced bioactivity and protein adsorption on the scaffold. The cyto-compatibility of the CS/PCL scaffold was examined using human osteoscarcoma cells (MG63) and found to be non toxic. Moreover, CS/PCL scaffold was found to support the attachment and proliferation of various cell lines such as mouse embryo fibroblasts (NIH3T3), murine aneuploid fibro sarcoma (L929), and MG63 cells. Cell attachment and proliferation was further confirmed by nuclear staining using 4′,6-diamidino-2-phenylindole (DAPI). All these results indicate that CS/PCL nanofibrous scaffold would be an excellent system for bone and skin tissue engineering.

Photoluminescent ZrO2:Eu3+ Nanofibers Prepared via Electrospinning

Europium-doped zirconium oxide (ZrO2:Eu3+) nanofibers were prepared via electrospinning, in which a mixture of zirconium chloride oxide octahydrate, europium nitrate hexahydrate, poly(vinyl pyrrolidone), dimethylformamide, and ethanol were electrospun at atmospheric conditions. Subsequent calcination to produce ZrO2:Eu3+ nanofibers with diameters around 300 nm. The crystal structure and photoluminescence of the ZrO2:Eu3+ nanofibers were studied as a function of dopant concentration and heating temperature. At a dopant concentration of 5 mol %, tetragonal phase crystals were observed. Photoluminescence spectra revealed several emission bands in the red region corresponding to the transition of 5D0→7FJ (J=1,2,3,4). Two most intense emission bands were observed at wavelengths of 606 and 591 nm due to the forced electric dipole (5D0→7F2) and magnetic dipole (5D0→7F1) transitions, respectively. This work demonstrates that one-dimensional photoluminescent materials can be generated by a two step electrospinning and calcination process.