In situ synthesis of iron oxide nanoparticles on poly(ethylene oxide) nanofibers through an electrospinning process

Iron oxide nanoparticle coated poly(ethylene oxide) nanofibers as organic–inorganic hybrids with 200–400‐nm diameters were prepared by the in situ synthesis of iron oxide nanoparticles on poly(ethylene oxide) nanofibers through the electrospinning of a poly(ethylene oxide) solution having Fe²⁺ and Fe³⁺ ions in a gaseous ammonia atmosphere. Transmission electron microscopy analysis proved the presence of iron oxide nanoparticles on the polymer nanofibers. The thermal properties of the nanofiber mat were also studied with differential scanning calorimetry and thermogravimetric analysis techniques. X‐ray diffraction showed that the formed iron oxide nanoparticles were maghemite nanoparticles. The results were compared with those of the electrospinning of a poly(ethylene oxide) solution having Fe²⁺ and Fe³⁺ ions and a pure poly(ethylene oxide) solution in an air atmosphere. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

ZnO nanocrystallites/cellulose hybrid nanofibers fabricated by electrospinning and solvothermal techniques and their photocatalytic activity

ZnO nanocrystallites have been in situ embedded in cellulose nanofibers by a novel method that combines electrospinning and solvothermal techniques. Zn(OAc)₂/cellulose acetate (CA) precursor hybrid nanofibers with diameter in the range of 160–330 nm were first fabricated via the electrospinning technique using zinc acetate as precursor, CA as the carrier, and dimethylformamide (DMF)/acetone(2 : 1) mixture as cosolvent. The precursor nanofibers were transformed into ZnO/cellulose hybrid fibers by hydrolysis in 0.1 mol/L NaOH aqueous solution. Subsequently, these hybrid fibers were further solvothermally treated in 180°C glycerol oil bath to improve the crystallite structure of the ZnO nanoparticles containing in the nanofibers. The structure and morphology of nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. It was found that hexagonal structured ZnO nanocrystallites with the size of ～ 30 nm were dispersed on the nanofiber surfaces and within the nanofibers with diameter of about 80 nm. The photocatalytic property of the ZnO/cellulose hybrid nanofibers toward Rhodamine (RhB) was tested under the irradiation of visible light. As a catalyst, it inherits not only the photocatalytic ability of nano‐ZnO, but also the thermal stability, good mechanical property, and solvent‐resistibility of cellulose nanofibers. The key advantages of this hybrid nanofiber over neat ZnO nanoparticles are its elasticity, dimensional stability, durability, and easy recyclability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Aureole nanofibers by electrospinning of PAMAM‐PEO solution

Poly(amido amine) (PAMAM) dendrimer‐polyethylene oxide (PEO) nanofibers as dendrimeric‐polymeric composite nanofibers were prepared via electrospinning of PEO solution containing PAMAM dendrimer. The resultant fibers were characterized by means of transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The morphology and thermal properties of PEO nanofibers with and without PAMAM dendrimer were compared and the effect of PAMAM concentration on morphology and thermal properties of the resultant fibers was studied. The fibers had a size range of about 400–1300 nanometer in diameter with aureole morphology in most regions. The phase change temperature, phase transition heat, and the crystallinity of the produced composite fibers were determined by DSC analyses. TGA was also used to confirm the presence of PAMAM and to determine the amount of it within the fibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and Substrate-Aided Alignment of Porphyrinated Poly(ethylene oxide) (PEO) Electrospun Nanofibers

Aligned and unaligned vanadium (IV) oxide meso-tetraphenyl porphine (VMP)/polyethylene oxide (PEO) hybrid nanofibers have been successfully synthesized by electrospinning technique. The nanofibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), atomic force microscopy (AFM), optical microscopy and scanning electron microscopy (SEM). The SEM and AFM analyses of the morphology showed that the nanofibers are cylindrical with diameters ranging from 400–700 nm. The AFM analysis also confirmed that the aligned nanofibers deposited on a small metallic spring are smoother than the unaligned ones deposited on FTO. FTIR analysis showed that the polar environment provided by the phenyl groups of VMP molecules modified the chemical configuration of PEO molecules, and XRD studies indicated that the VMP molecules were homogeneously distributed within the PEO matrix.     

Polymer nanofiber‐templated fabrication and characterization of gallium oxide nanofibers consisting of granular nanoparticles

Gallium oxide (β‐Ga₂O₃) is an interesting semiconductor that has a wide bandgap and can be used as an optoelectronic material in flat‐panel displays, solar energy conversion devices and optical limiters for UV light. However, it is difficult to fabricate and process Ga₂O₃ nanofibers for actual optoelectronic applications. When the excellent processability of polymeric materials is introduced into the inorganic nanofiber fabrication process, this limitation can be easily overcome. The aim of the research reported was to prepare granular Ga₂O₃ nanofibers utilizing an electrospun polyacrylonitrile nanofiber template combined with sol‐gel technology. Ga₂O₃ nanofibers were successfully fabricated by electrospinning a solution of polyacrylonitrile mixed with gallium nitrate and subsequent calcination. The surface and bulk morphologies of the calcined nanofibers investigated using field‐emission scanning electron microscopy and transmission electron microscopy (TEM) indicated that Ga₂O₃ nanofibers were constructed by the fusion of gallium oxide nanoparticles. TEM bright‐field images combined with selected‐area electron diffraction indicated that the average diameter of the Ga₂O₃ nanofibers produced was ca 55 nm and the crystalline structure was β‐Ga₂O₃ with a monoclinic unit cell. Furthermore, the photoluminescence spectrum of the Ga₂O₃ nanofibers exhibited two strong green emission peaks and one UV emission peak. Copyright © 2010 Society of Chemical Industry     

Low Temperature Carbothermal Reduction Synthesis of ZrC Nanofibers via Cyclized Electrospun PVP/Zr(OPr)4 Hybrid

The fabrication capability of zirconium carbide (ZrC) nanofibers by a novel polymeric solution was examined using electrospinning method. The electrospinnable solution was prepared from the reaction of zirconium n‐propoxide (Zr(OPr)₄) with acetylacetone and acetic acid followed by the addition of polyvinylpyrrolidone (PVP) solution. By utilizing thermal and microstructural analyses such as differential scanning calorimetry–thermogravimetry (DSC–TG), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET), the effect of heat treatment type on the morphology and crystallinity of as‐spun PVP/Zr(OPr)₄ hybrid fibers was examined. The results showed that direct carbonization treatment of as‐spun fibers under argon atmosphere led to spherical ZrC aggregates in lack of fibrillar morphology, whereas carbonization coupled with cyclization could be recognized as the unique template to govern the morphology and crystallinity of ZrC nanofibers. Carbonization of the cyclized fibers at 1550°C in flowing argon atmosphere produced the thick, fragmented rosary‐like fibers with a diameter of 357 nm, while through a 100°C decrease in carbonization temperature to 1450°C, the thin, smooth, long, and uniform ZrC nanofibers with 176 nm diameter and a medium surface area of 23 m²/g were obtained.     

Studies on the synthesis of electrospun PAN‐Ag composite nanofibers for antibacterial application

We have successfully synthesized polyacrylonitrile (PAN) nanofibers impregnated with Ag nanoparticles by electrospinning method at room temperature. Briefly, the PAN‐Ag composite nanofibers were prepared by electrospinning PAN (10% w/v) in dimethyl formamide (DMF) solvent containing silver nitrate (AgNO₃) in the amounts of 8% by weight of PAN. The silver ions were reduced into silver particles in three different methods i.e., by refluxing the solution before electrospinning, treating with sodium borohydride (NaBH₄), as reducing agent, and heating the prepared composite nanofibers at 160°C. The prepared PAN nanofibers functionalized with Ag nanoparticles were characterized by field emission scanning electron microscopy (FESEM), SEM elemental detection X‐ray analysis (SEM‐EDAX), transmission electron microscopy (TEM), and ultraviolet‐visible spectroscopy (UV‐VIS) analytical techniques. UV‐VIS spectra analysis showed distinct absorption band at 410 nm, suggesting the formation of Ag nanoparticles. TEM micrographs confirmed homogeneous dispersion of Ag nanoparticles on the surface of PAN nanofibers, and particle diameter was found to be 5–15 nm. It was found that all the three electrospun PAN‐Ag composite nanofibers showed strong antibacterial activity toward both gram positive and gram negative bacteria. However, the antibacterial activity of PAN‐Ag composite nanofibers membrane prepared by refluxed method was most prominent against S. aureus bacteria. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Comparison of dye degradation potential of biosynthesized copper oxide,manganese dioxide,and silver nanoparticles using <Emphasis Type="Italic">Kalopanax pictus</Emphasis> plant extract

Copper(II) oxide (CuO), manganese dioxide (MnO₂), and silver (Ag) nanoparticles were synthesized using Kalopanax pictus plant extract. The nanoparticle synthesis was monitored using UV-visible spectra. The occurrence of each peak at 368, 404, and 438 nm wavelength indicated the synthesis of CuO, MnO₂, and Ag nanoparticles, respectively. The synthesized nanoparticles were characterized by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Catalytic potentials of the synthesized nanoparticles were compared to degrade two typical acidic and basic dyes (Congo red and Safranin O). The degradation ability of MnO₂ nanoparticles against Congo red was higher than that of Ag and CuO nanoparticles. All three types of nanoparticles showed a similar degradation ability against Safranin O over 80%. This study demonstrates that biologically synthesized nanoparticles using Kalopanax pictus are good agents for degradation of dyes.     

Characterization of PVAc/TiO2 hybrid nanofibers: From fibrous morphologies to molecular structures

Polyvinyl acetate (PVAc)/titanium dioxide (TiO₂) hybrid nanofibers were fabricated by combining sol–gel process with electrospinning technology, which consisted of PVAc as organic segment and TiO₂ as inorganic part. The surface structures of the PVAc/TiO₂ hybrid nanofibrous mats were examined using scanning electron microscopy (SEM). The surface morphology and bulk structures of single nanofiber were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to analyze the chemical structures of the PVAc/TiO₂ hybrid nanofibers. SEM scanning revealed that the fibrous structure was formed. AFM observations presented a significant difference in the morphology of the nanofibers before and after hybridization. It was observed from TEM images that some black streaks with various lengths distributed in a nanofiber. The FTIR analysis indicated the newly formed associated hydrogen bond because of the hybrid effect between PVAc and TiO₂ sol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Encapsulation of manganese oxides nanocrystals in electrospun carbon nanofibers as free-standing electrode for supercapacitors

Flexible composites with manganese oxides (MnO_x) nanocrystals encapsulated in electropun carbon nanofibers were successfully fabricated via a simple and practical combination of electrospinning and carbonization process. The as-formed MnO_x/carbon nanofibers composites have a rough surface with MnO_x nanoparticles well embedded in the carbon nanofibers backbones. When used as electrodes for supercapacitor, the resulting MnO_x/carbon nanofiber composites exhibit good electrochemical performance with a specific capacitance of 174.8 F g⁻¹ at 2 mV s⁻¹ in 0.5 M Na₂SO₄ electrolyte, a good rate capability at high current density and long-term cycling stability. It is expected that such freestanding composites could be promising electrodes for high-performance supercapacitors.     

Fabrication and characterization of flexible ruthenium oxide-loaded polyaniline/poly(vinyl alcohol) nanofibers

Polyaniline/poly(vinyl alcohol)/ruthenium oxide (RuO₂) composite nanofibers were produced by electrospinning technique. Hydrous ruthenium chloride was used as a precursor at different concentrations, and the samples were annealed at 200°C. The morphology of the nanofibers was investigated by scanning electron microscopy. The average diameter of the produced nanofibers is between 200 and 300 nm. Fourier transform infrared spectroscopy and Raman spectroscopy were used for the investigation of the vibration modes and structure of the samples. Differential scanning calorimeter, and thermal gravimetric analysis up to 400°C revealed the crystallinity degree and thermal stability of the samples. Impedance spectroscopy for the samples with capacitor structure was conducted as function of RuO₂ concentration and temperature. The tests revealed the decrease of electrical resistivity and activation energy with increasing RuO₂ concentration for the as-prepared samples, while the annealed samples showed lower activation energy values of ~0.1 eV with increasing the concentration of RuO₂. The electrical properties of the fabricated composite nanofibers could be controlled that make them suitable to be utilized in devices for energy storage applications.     

Prussian blue nanoparticles potentiostatically electrodeposited on indium tin oxide/chitosan nanofibers electrode and their electrocatalysis towards hydrogen peroxide

Chitosan (CS) nanofibers were successfully used to modify indium tin oxide (ITO) electrode by electrospinning technique. Then, Prussian blue (PB) nanoparticles were electrodeposited on the CS nanofibers by potentiostatic technique in an acidic solution containing single ferricyanide. By this method, direct synthesis of PB nanoparticles on the nanofibers that were used for modifying electrode came true. Transmission electronic microscopy (TEM) showed that the average size of PB nanoparticles was about 50 nm. Selected-area electron diffraction (SAED) showed diffusive diffraction spots, indicating the mosaic structure of the PB nanoparticles on the CS nanofibers. X-ray powder diffraction (XRD) displayed the long-range disorder of CS nanofibers and demonstrated the formation of PB nanoparticles. Results of the scanning electron microscope (SEM) images indicated that the PB nanoparticles could be electrodeposited on the CS nanofibers. The amount of the PB nanoparticles on the CS nanofibers increased with increasing potential value of the electrodeposition. In addition, the cyclic voltammetric response displayed two characteristic redox couples of PB. The modified electrode exhibited electrocatalytic activity towards reduction of H₂O₂.     

Functionalization of electrospun nanofibers of natural cotton cellulose by cerium dioxide nanoparticles for ultraviolet protection

Nanofibers of natural cotton cellulose with a degree of polymerization above 10,000 were prepared by electrospinning; they were then functionalized with a rare‐earth nano‐oxide material of cerium dioxide (CeO₂) by means of the hydrothermal method to obtain the designated properties. The morphology, structure, and properties of the as‐obtained nanocomposite fibers were characterized by scanning electron microscopy, transmission electron microscopy, energy‐dispersive spectroscopy, X‐ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet (UV)–visible spectrophotometry. The results show that hydrothermally grown CeO₂ nanoparticles exhibited a polycrystalline cubic fluorite structure and could be dispersed uniformly on the surface of the cellulose nanofiber. The strong interface and electrostatic interactions between the nanoparticles and nanofibers effectively prevented nanoparticle fall‐off. The modified natural cotton cellulose nanofibers showed excellent protection against UV radiation because of the function of the CeO₂ particles. Such cellulose nanocomposite materials could have potential applications in UV protection for data‐storage or memory devices. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1524–1529, 2013     

Hybrid 2D nanofibers based on poly(ethylene oxide)/polystyrene matrix and poly(ferrocenylphosphinoboranes) as functional agents

Template smart inorganic polymers within an organic polymeric matrix to form hybrid nanostructured materials are a unique approach to induce novel multifunctionality. In particular, the fabrication of one-dimensional materials via electrospinning is an advanced tool, which has gained success in fulfilling the purpose to fabricate two-dimensional nanostructured materials. We have explored the formation of novel hybrid nanofibers by co-spinning of poly(ferrocenylphosphinoboranes) Fe A [{Fe(C₅H₅)(C₅H₄CH₂PHBH₂)} _n] and Fe B [{Fe(C₅H₅)(C₅H₄PHBH₂)} _n] with poly(ethylene oxide) (PEO) and polystyrene (PS). Fe A and Fe B contain main-group elements and a ferrocene moiety as pendent group and have different properties compared to their only carbon-containing counterparts. The use of PEO and polystyrene provided a matrix to spin those inorganic polymers as hybrid nanofibers which were collected in the form of a nonwoven mat. They were characterized by multinuclear NMR spectroscopy, scanning electron microscopy (SEM), and IR spectroscopy. Thermal properties of the polymers have been checked by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). ¹H, ³¹P, and ¹¹B NMR and IR spectroscopy revealed the nature and types of interactions of the components after co-spinning. The SEM micrographs identify the underlying unidirectional morphology of the generated hybrid nanofibers. Nonetheless, the DSC and TGA confirmed the significant boost toward the thermal stability of the resultant multifunctional fibers. It is believed that these unique types of multifunctional electrospun nanofibers will open new avenues toward the next generation of miniaturized devices.     

Field-responsive superparamagnetic composite nanofibers by electrospinning

Superparamagnetic polymeric nanofibers were produced via an electrospinning technique from colloidally-stable suspensions of magnetite nanoparticles in polyethylene oxide and polyvinyl alcohol solutions. The magnetite nanoparticles were aligned in columns parallel to the fiber axis direction within the fiber by the electrospinning process. The polymer/magnetite nanofibers exhibited superparamagnetic behavior at room temperature, and deflected in the presence of an applied magnetic field. The mechanical properties of the nanofibers were maintained or improved after incorporating the magnetite nanoparticles.     

The effect of B4C addition to MnO2 in a cathode material for battery applications

Boron carbide (B₄C) added manganese dioxide (MnO₂) used as a cathode material for a Zn-MnO₂ battery using aqueous lithium hydroxide (LiOH) as the electrolyte is known to have higher discharge capacity but with a lower average discharge voltage than pure MnO₂ (additive free). The performance is reversed when using potassium hydroxide (KOH) as the electrolyte. Herein, the MnO₂ was mixed with 0, 5, 7 and 10 wt.% of boron carbide during the electrode preparation. The discharge performance of the Zn|LiOH|MnO₂ battery was improved by the addition of 5-7 wt.% boron carbide in MnO₂ cathode as compared with the pure MnO₂. However, increasing the additive to 10 wt.% causes a decrease in the discharge capacity. The performance of the Zn|KOH|MnO₂ battery was retarded by the boron carbide additive. Transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy analysis (EDS) results show evidence of crystalline MnO₂ particles during discharging in LiOH electrolyte, whereas, manganese oxide particles with different oxygen and manganese counts leading to mixture of phases is observed for KOH electrolyte which is in agreement with X-ray diffraction (XRD) data. The enhanced discharge capacity indicates that boron atoms promote lithium intercalation during the electrochemical process and improved the performance of the Zn|LiOH|MnO₂ battery. This observed improvement may be a consequence of B₄C suppressing the formation of undesirable Mn(III) phases, which in turn leads to enhanced lithium intercalation. Too much boron carbide hinders the charge carrier which inhibits the discharge capacity.     

Interior synthesizing of ZnO nanoflakes inside nylon‐6 electrospun nanofibers

Doping of the polymeric electrospun nanofibers by metal oxides nanoparticles is usually performed by electrospinning of a colloidal solution containing the metal oxide nanoparticles. Besides the economical aspects, electrospinning of colloids is not efficient compared with spinning of sol–gels, moreover well attachment of the solid nanoparticles is not guaranteed. In this study, reduction of zinc acetate could be performed inside the nylon‐6 electrospun nanofibers; so polymeric nanofibers embedding ZnO nanoflakes were obtained. Typically, zinc acetate/nylon‐6 electrospun nanofibers were treated hydrothermally at 150°C for 1 h. Besides the utilized characterization techniques, PL study affirmed formation of ZnO. The produced nanofibers showed a good antibacterial activity which improves with increasing ZnO content. Overall, the present study opens new avenue to synthesize hybrid nanofibers by a facile procedure. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Chain conformation,crystallization behavior,electrical and mechanical properties of electrospun polymer-carbon nanotube hybrid nanofibers with different orientations

An improved electrospinning technique was used to produce poly(ethylene oxide) (PEO) and PEO-multi-walled carbon nanotube (MWCNT) hybrid nanofibers. By this technique, both the orientation of MWCNTs in the electrospun PEO nanofibers and the orientation of electrospun PEO–MWCNT hybrid nanofibers can be controlled. The morphologies of the as-spun PEO–MWCNT hybrid nanofibers and the dispersion and orientation of MWCNTs in the fiber matrix were observed by scanning and transmission electron microscopy. The effect of electrospinning process and the incorporation of MWCNTs on the chain conformation and semicrystalline framework of PEO were examined by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, and compared with pure PEO and PEO–MWCNT films prepared by casting. Finally, to investigate how the fiber assemblies affect the mechanical and electrical properties of the hybrid materials, tensile testing and impedance analysis were performed on randomly oriented, uniaxially and biaxially oriented PEO–MWCNT hybrid nanofiber mats. The results indicated that both the uniaxially and biaxially oriented assembled hybrid materials have better tensile strength, modulus, and electrical conductivity compared with random nanofibers.     

Enhanced microwave absorption properties of electrospun PEK‐C nanofibers loaded with Fe3O4/CNTs hybrid nanoparticles

The phenolphthalein polyetherketone (PEK‐C) nanofibers loaded with Fe₃O₄/carbon nanotubes (CNTs) hybrid nanoparticles were synthesized by electrospinning technique. The morphology, composition, and thermal stability of composite nanofibers were characterized by scanning electron microscope, energy dispersive spectrometer, and thermogravimetric analysis, respectively. The complex permittivity and permeability of composite nanofibers in the microwave frequency range of X band (8.2–12.4 GHz) were measured by vector network analyzer using wave‐guide method. The results show that the permittivity and dielectric loss were enhanced obviously by adding CNTs. With the W _CNTs increasing to 5%, the minimum R _L value reaches ?41.4 dB at 9.3 GHz with a matching thickness of 1.7 mm and exceeds ?10 dB with thickness of 1.4–1.8 mm in the whole X band. The enhanced microwave absorption properties are mainly attributed to tunable electromagnetic parameters and thus a better impedance matching characteristic by mixing CNTs with Fe₃O₄ nanoparticles within proper ranges loaded in PEK‐C nanofibers. POLYM. ENG. SCI., 57:1186–1192, 2017. © 2017 Society of Plastics Engineers     

Highly efficient synthesis of graphene/MnO2 hybrids and their application for ultrafast oxidative decomposition of methylene blue

A highly efficient method has been reported to fabricate the reduced graphene oxide/MnO₂ (RGO/MnO₂) hybrid materials, a kind of catalysts for oxidative decomposition of methylene blue (MB). The pristine suspension of graphene oxide/manganese sulfate (GO/MnSO₄) produced by the modified Hummers method is in situ transformed into GO/MnO₂ composites in combination with KMnO₄, and then further into RGO/MnO₂ composites by means of glucose-reduction. It is found that MnO₂ nanoparticles with the size of 20–30 nm are uniformly distributed in the structure of RGO. A series of composites with different mass ratios of RGO to MnO₂ has been proved superior catalytic activities, much higher than that of the bare MnO₂ for decomposition of MB dye in the presence of H₂O₂. Typically, 50 mL of MB (50 mg L⁻¹) can be completely decolorized and nearly 66% mineralized at 50 °C in 5 min with 10 mg of the RGO/MnO₂ hybrid. According to the adsorption–oxidation–desorption mechanism, the high activity of RGO/MnO₂ composites for decomposition of MB is closely related to the positive synergistic effect of RGO and MnO₂ with the assistance of H₂O₂.