Nanofiber Webs Research Articles

Antibacterial electrospun zein nanofibrous web encapsulating thymol/cyclodextrin-inclusion complex for food packaging

Thymol (THY)/γ-Cyclodextrin(γ-CD) inclusion complex (IC) encapsulated electrospun zein nanofibrous webs (zein-THY/γ-CD-IC-NF) were fabricated as a food packaging material. The formation of THY/γ-CD-IC (1:1 and 2:1) was proved by experimental (X-ray diffraction (XRD), thermal gravimetric analysis (TGA), 1H NMR) and computational techniques. THY/γ-CD-IC (2:1) exhibited higher preservation rate and stability than THY/γ-CD-IC (1:1). It is worth mentioning that zein-THY/γ-CD-IC-NF (2:1) preserved much more THY as observed in TGA and stability of THY/γ-CD-IC (2:1) was higher, as shown by a modelling study. Therefore, much more THY was released from zein-THY/γ-CD-IC-NF (2:1) than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). Similarly, antibacterial activity of zein-THY/γ-CD-IC-NF (2:1) was higher than zein-THY-NF and zein-THY/γ-CD-IC-NF (1:1). It was demonstrated that zein-THY/γ-CD-IC-NF (2:1) was most effective in inhibiting the growth of bacteria on meat samples. These webs show potential application as an antibacterial food packaging material.

Controlled synthesis of anisotropic hexagonal boron nitride nano-web

The assembly of one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) nanomaterial show entirely different properties than their individual counterparts. Since the shape of nanomaterials plays a crucial role in designing devices with desired applications, relentless efforts are on-going to obtain the parameters for controlling the shape of the final product. Present study concerns the synthesis and growth of a combined 2D and 3D structure of Hexagonal Boron Nitride Nanofibers Web (BNNFs-Web) from 1D structure of BNNFs. Magnesium catalytic layer deposited on Silicon substrate produces Web-like nucleation sites when etches with NH3 flow at 300°C. The precursor's mixture of B, γ-Fe2O3 and MgO annealed at 500°C uses these nucleation sites as a pattern, and grow BNNFs-Web in a unique 2D and 3D configuration at 1000°C. XRD, Raman and FTIR spectroscopies confirmed the h-BN phase of the as-synthesized BNNFs-Web. This unique 2D and 3D material can offer distinguish features with improved properties as compared to other nanostructures of h-BN. Such a material can be a much better choice for its potential applications in different fields of bio-medical, microelectronic mechanical system and solid state neutron detectors.

Core/shell structured carbon nanofiber/platinum nanoparticle hybrid web as a counter electrode for dye-sensitized solar cell

Core/shell structured carbon nanofiber/platinum nanoparticle (Pt NP) hybrid web was prepared and applied to counter electrode (CE) of dye-sensitized solar cell. Nanofibers (NFs) composed of polyacrylonitrile (co)polymer and Pt precursors were first prepared by coaxial electrospinning. A series of thermal treatment procedures afforded simultaneous transformations of the precursors to carbon nanofiber (CNF) web with Pt NPs in the shell layer. This spatial distribution of Pt NPs in CNF increased the electrocatalytic activity of the CNF web. The CE exhibited a low charge transfer resistance at the interface between CE and electrolyte, demonstrating synergistic combination of Pt NPs and the CNF.

Nanofibrous web quality in dependence on the preparation of poly(ethylene oxide) aqueous solutions

The method of preparation of polymer solutions significantly influences the quality of the corresponding electrospun nanofibrous webs. However, this factor is often ignored, and in a majority of presentations concerning the electrospinning process, the applied method is not mentioned. This paper compares the influence of magnetic stirring, vibrational shaking and ultrasonication on a solution of poly(ethylene oxide) in distilled water. Along with the methods of preparation, other parameters were altered such as concentration, intensity of mixing and molecular weight. The best results from the viewpoint of electrospinning were achieved with moderate magnetic stirring.

Electrospinning of cyclodextrin/linalool-inclusion complex nanofibers: Fast-dissolving nanofibrous web with prolonged release and antibacterial activity

The volatility and limited water solubility of linalool is a critical issue to be solved. Here, we demonstrated the electrospinning of polymer-free nanofibrous webs of cyclodextrin/linalool-inclusion complex (CD/linalool-IC-NFs). Three types of modified cyclodextrin (HPβCD, MβCD, and HPγCD) were used to electrospin CD/linalool-IC-NFs. Free-standing CD/linalool-IC-NFs facilitate maximum loading of linalool up to 12% (w/w). A significant amount of linalool (45–89%) was preserved in CD/linalool-IC-NFs, due to enhancement in the thermal stability of linalool by cyclodextrin inclusion complexation. Remarkably, CD/linalool-IC-NFs have shown fast-dissolving characteristics in which these nanofibrous webs dissolved in water within two seconds. Furthermore, linalool release from CD/linalool-IC-NFs inhibited growth of model Gram-negative (E. coli) and Gram-positive (S. aureus) bacteria to a great extent. Briefly, characteristics of liquid linalool have been preserved in a solid nanofiber form and designed CD/linalool-IC-NFs confer high loading capacity, enhanced shelf life and strong antibacterial activity of linalool.

High-output acoustoelectric power generators from poly(vinylidenefluoride-co-trifluoroethylene) electrospun nano-nonwovens

Conversion of mechanical forces, vibrations and sound which have energy in the range of milli- to tens of watts (also referred to as “small kinetic energies” in this paper) into electricity has received global attention owing to the potential in powering electronic devices. However, most of the small kinetic energy generators can only generate electric power below 1µW/cm3. As a result, an energy storage device is required to accumulate the energy generated until it reaches a sufficient level. Herein, we report the exceptionally-high acoustoelectric conversion ability of randomly-orientated electrospun poly(vinylidenefluoride-co-trifluoroethylene) nanofiber nonwoven webs. The optimized device under sound is able to generate peak voltage and current of 14.5V and 28.5μA with a volume power density output of 306.5μW/cm3 (5.9mW/cm3 based on nanofiber web thickness). Without accumulation in any energy storage unit, the electricity generated by the nanofiber device is sufficient to light up tens of commercial LEDs, run electrochemical reactions and protect metals from corrosion. Such a novel acoustoelectric generator may offer an effective solution to recycling noise pollution into usable electricity.

Ultrathin free-standing electrospun carbon nanofibers web as the electrode of the vanadium flow batteries

Ultrathin free-standing electrospun carbon nanofiber web (ECNFW) used for the electrodes of the vanadium flow battery (VFB) has been fabricated by the electrospinning technique followed by the carbonization process in this study to reduce the ohmic polarization of the VFB. The microstructure, surface chemistry and electrochemical performance of ECNFW carbonized at various temperatures from 800 to 1400°C have been investigated. The results show that ECNFW carbonized at 1100°C exhibits the highest electrocatalytic activity toward the V2+/V3+ redox reaction, and its electrocatalytic activity decreases along with the increase of carbonization temperature due to the drooping of the surface functional groups. While for the VO2+/VO2+ redox couple, the electrocatalytic activity of ECNFW carbonized above 1100°C barely changes as the carbonization temperature rises. It indicates that the surface functional groups could function as the reaction sites for the V2+/V3+ redox couple, but have not any catalytic effect for the VO2+/VO2+ redox couple. And the single cell test result suggests that ECNFW carbonized at 1100°C is a promising material as the VFB electrode and the VFB with ECNFW electrodes obtains a super low internal resistance of 250mΩcm2.

Development of Ultraviolet (UV) Radiation Protective Fabric Using Combined Electrospinning and Electrospraying Technique

The article reports a novel technique for functionization of nanoweb to develop ultraviolet (UV) radiation protective fabric. UV radiation protection effect is produced by combination of electrospinning and electrospraying technique. A nanofibrous web of polyvinylidene difluoride (PVDF) coated on polypropylene nonwoven fabric is produced by latest nanospider technology. Subsequently, web is functionalized by titanium dioxide (TiO2). The developed web is characterized for evaluation of surface morphology and other functional properties; mechanical, chemical, crystalline and thermal. An optimal (judicious) nanofibre spinning condition is achieved and established. The produced web is uniformly coated by defect free functional nanofibres in a continuous form of useable textile structural membrane for ultraviolet (UV) protective clothing. This research initiative succeeds in preparation and optimization of various nanowebs for UV protection. Field Emission Scanning Electron Microscope (FESEM) result reveals that PVDF webs photo-degradative behavior is non-accelerated, as compared to normal polymeric grade fibres. Functionalization with TiO2 has enhanced the photo-stability of webs. The ultraviolet protection factor of functionalized and non-functionalized nanowebs empirically evaluated to be 65 and 24 respectively. The developed coated layer could be exploited for developing various defence, para-military and civilian UV protective light weight clothing (tent, covers and shelter segments, combat suit, snow bound camouflaging nets). This research therefore, is conducted in an attempt to develop a scientific understanding of PVDF fibre coated webs for photo-degradation and applications for defence protective textiles. This technological research in laboratory scale could be translated into bulk productionization.

Mechanical Energy‐to‐Electricity Conversion of Electron/Hole‐Transfer Agent‐Doped Poly(Vinylidene Fluoride) Nanofiber Webs

Electrospun poly(vinylidene fluoride) (PVDF) nanofibers have shown novel property to convert kinetic energy into electricity. However, most of the PVDF nanofiber energy devices are based on pure PVDF. In this paper, the effect of small molecule doping on PVDF nanofiber diameter, β phase content, and mechanical‐to‐electrical energy conversion property is reported. Two chemicals, tri‐p‐tolylamine (TTA) and 2‐(4‐tert‐butylphenyl)‐5‐(4‐biphenylyl)‐1,3,4‐oxadiazole (Butyl‐PBD) which have electron‐ and hole‐transfer features, respectively, are chosen as dopants. When the nanofibers contain 0.5% TTA or 1% Butyl‐PBD, they show high β phase content and electric outputs. By combining a layer of nanofiber web which contained TTA with a layer of nanofiber web containing Butyl‐PBD, the voltage output is changed to 3.1 V, increasing by ≈100% when compared with the single layer nanofiber device of the same thickness. In addition, asymmetric electric outputs are observed in the two layer energy device. These novel features are probably attributed to the high internal polarity across the nanofiber web. image

Syringeless Electrospinning toward Versatile Fabrication of Nanofiber Web

Although electrospinning is considered a powerful and generic tool for the preparation of nanofiber webs, several issues still need to be overcome for real-world applications. Most of these issues stem from the use of a syringe-based system, where the key factor influencing successful electrospinning is the maintenance of several subtle balances such as those of between the mass and the electrical state. It is extremely difficult to maintain these balances throughout the spinning process until all the polymeric solution in the syringe has been consumed. To overcome these limitations, we have developed a syringeless electrospinning technique as an alternative and efficient means of preparing a nanofiber web. This new technique uses a helically probed rotating cylinder. This technique can not only cover conventional methods, but also provides several advantages over syringe-based and needless electrospinning in terms of productivity (6 times higher) and processibility. For example, we can produce nanofibers with highly crystalline polymers and nanofiber-webs comprising networks of several different polymers, which is sometimes difficult in conventional electrospinning. In addition, this method provides several benefits for colloidal electrospinning as well. This method should help expand the range of applications for electrospun nanofiber webs in the near future.

Bacteria encapsulated electrospun nanofibrous webs for remediation of methylene blue dye in water

In this study, preparation and application of novel biocomposite materials that were produced by encapsulation of bacterial cells within electrospun nanofibrous webs are described. A commercial strain of Pseudomonas aeruginosa which has methylene blue (MB) dye remediation capability was selected for encapsulation, and polyvinyl alcohol (PVA) and polyethylene oxide (PEO) were selected as the polymer matrices for the electrospinning of bacteria encapsulated nanofibrous webs. Encapsulation of bacterial cells was monitored by scanning electron microscopy (SEM) and fluorescence microscopy, and the viability of encapsulated bacteria was checked by live/dead staining and viable cell counting assay. Both bacteria/PVA and bacteria/PEO webs have shown a great potential for remediation of MB, yet bacteria/PEO web has shown higher removal performances than bacteria/PVA web, which was probably due to the differences in the initial viable bacterial cells for those two samples. The bacteria encapsulated electrospun nanofibrous webs were stored at 4°C for three months and they were found as potentially storable for keeping encapsulated bacterial cells alive. Overall, the results suggest that electrospun nanofibrous webs are suitable platforms for preservation of living bacterial cells and they can be used directly as a starting inoculum for bioremediation of water systems.

Design and Development of Composite Nonwoven Filter for Pre-filtration of Textile Effluents Using Nano-technology

The main aim of this study is to test the feasibility of using composite membrane of nonwovens and Nanofibre for the pre-filtration treatment of reactive dye bath effluent from the textile industry. The results of ultraviolet spectrophotometer of filtered and non-filtered sample show that the cleaning efficiency of effluent water will be achieved in the range of 70-80%. Cleaning efficiency of the Nano-filter filter remains around 70%. But a composite nonwoven filter made up of polyester fibre needle punched nonwoven and Nano-fibre web; the cleaning efficiency can reach as high as 90%.

Manganese dioxide nanowires on carbon nanofiber frameworks for efficient electrochemical device electrodes

Hierarchically nanostructured composite electrodes were prepared by the electrodeposition of manganese dioxide nanowires (MnO2 NWs) with 5–20 nm diameters on electrospun carbon nanofiber (CNF) webs with diameters of 250 and 650 nm.

Mitigation of PFSA membrane chemical degradation using composite cerium oxide–PFSA nanofibres

A perfluorosulfonic acid ionomer–cerium oxide nanofibre web integrated into an asymmetric composite membrane significantly reduces fuel cell membrane degradation, especially with the modified surface placed at the anode.

Design and synthesis of a free-standing carbon nano-fibrous web electrode with ultra large pores for high-performance vanadium flow batteries

A highly porously free-standing nano fibrous web electrode has been designed and fabricated for VFB through a novel horizontally-opposed blending electrospinning method in this study.

Mechanically enhanced electrospun nanofibers for wastewater treatment

A novel high-performance polyamide 6, polyacrylonitrile and polyvinylidene fluoride nanofibers were fabricated using industrial production Nanospider equipment for liquid filtration as microfilters. The application of nanofibers has been hindered by their poor mechanical strength. This work developed a feasible approach to preparing mechanically strong nanofiber webs. The mechanical strength of the nanofibers was enhanced using special lamination technique on a supporting layer. Experimental results show that the mechanical strength of the nanofibers enhanced more than 5 times while high porosity and liquid permeability retain. The separation results indicate that nanofibers have a potential to be used in liquid filters.

Porous ultrathin carbon nanobubbles formed carbon nanofiber webs for high-performance flexible supercapacitors

Porous ultrathin carbon nanobubbles formed carbon nanofiber webs exhibit 94.1% capacitance retention after 35 000 cycles at a current density of 10 A g−1.

Fabrication of wearable semiconducting piezoelectric nanogenerator made with electrospun-derived zinc sulfide nanorods and poly(vinyl alcohol) nanofibers

We report the fabrication of flexible, low cost, and wearable piezoelectric nanogenerators (NG) composed of a poly(vinyl alcohol) (PVA) nanofiber web and oriented zinc sulfide (ZnS) nanorods (NRs) by a facile and scalable electrospinning technique. The piezoelectric performance of the NG is found to be increased by simply stacking the nanofiber web mats, where the ZnS NRs are incorporated in the PVA fiber matrix. Furthermore, we also designed a large area wearable nanogenerator (WNG) to harvest mechanical energy from acoustic random vibrations and convert it into electrical energy, and an improved acoustic sensitivity of 2 V Pa−1 is observed. This indicates that the WNG is ultrasensitive to random mechanical vibration, and possesses potential utility as a sustainable power source and sensitive pressure sensor particularly suited for portable electronics and wearable technology.

Ultrasonic-assisted deacetylation of cellulose acetate nanofibers: A rapid method to produce cellulose nanofibers

Herein we report a rapid method for deacetylation of cellulose acetate (CA) nanofibers in order to produce cellulose nanofibers using ultrasonic energy. The CA nanofibers were fabricated via electrospinning thereby treated with NaOH and NaOH/EtOH solutions at various pH levels for 30, 60 and 90min assisted by ultrasonic energy. The nanofiber webs were optimized by degree of deacetylation (DD%) and wicking behavior. The resultant nanofibers were further characterized by FTIR, SEM, WAXD, DSC analysis. The DD% and FTIR results confirmed a complete conversion of CA nanofibers to cellulose nanofibers within 1h with substantial increase of wicking height. Nanofibers morphology under SEM showed slightly swelling and no damage of nanofibers observed by use of ultrasonic energy. The results of ultrasonic-assisted deacetylation are comparable with the conventional deacetylation. Our rapid method offers substantially reduced deacetylation time from 30h to just 1h, thanks to the ultrasonic energy.

Preparation of PAN-based electrospun nanofiber webs containing Ni-ZnO as high performance visible light photocatalyst

The one dimensional (1D) Ni-ZnO nanoparticles have been synthesized by a simple hydrothermal method. A novel photocatalyst of nanostructured Ni-ZnO which immobilized on polyacrylonitrile nanofibers were successfully fabricated using electrospinnig technique. The structures of nanofibers were characterized by various techniques including Scanning Electron Microscope (SEM), X-ray powder Diffraction (XRD), Fourier transform infrared (FT-IR), UV-Vis diffuse reflectance (DR) and thermogravimetric analys (TGA). The Ni-ZnO/PAN nanofibers photodegradation efficiency was optimized with factorial design method in order to act highly effective in the photocatalytic degradation of Methyle orange (MO). The highest decolorizing efficiencies using introduced material were achieved by 0.8 g l-1 of catalyst and 10 mg l-1 of MO at natural pH under visible light irradiation. The obtained results exhibited that Ni-ZnO/PAN nanofibers have high visible light photocatalitic activities. Overall, the presented material can be used as an efficient, low cost and healthily secure photocatalyst in the field of water treatment.