S. Fakirov
Abstract
In this short communication, an attempt is undertaken to demonstrate that the widely used practice to call the electrospun polymers from their solutions and melts “polymer nanofibers” is hardly correct for the following reasons. The polymer fibers prepared by means of the common melt-spinning ...
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In this short communication, an attempt is undertaken to demonstrate that the widely used practice to call the electrospun polymers from their solutions and melts “polymer nanofibers” is hardly correct for the following reasons. The polymer fibers prepared by means of the common melt-spinning are characterized by perfect molecular orientation of the parallel aligned macromolecules leading to superior mechanical performance. The electrospun polymers are also flexible cylindrical formations but with macromolecules in isotropic, non-oriented state and distinguished by poor mechanical properties, frequently inferior than those of the same polymer in isotropic state. For this reason, it is suggested to call these materials “fiber-like nanomaterials” instead of “polymer nanofiber”. The real target of the communication is to challenge the electrospinning community to modify the manufacturing process in such a way that the final nanomaterial is characterized by perfect molecular orientation resulting in excellent, typical for polymer fibers mechanical properties, which will offer wide real applications of these nanofibers.
Victor Jaya Nesamony; Namagal Selvan
Abstract
The nanostructured material properties are different from the bulk materials. Nanofibers are widely studied for many applications like tissue engineering, wound dressings, electronics, storage, catalysts, protective clothing, sensors, and cosmetics. In this study, pure form of one-dimensional TiO2 nanofibers ...
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The nanostructured material properties are different from the bulk materials. Nanofibers are widely studied for many applications like tissue engineering, wound dressings, electronics, storage, catalysts, protective clothing, sensors, and cosmetics. In this study, pure form of one-dimensional TiO2 nanofibers have been successfully obtained by electrospinning technique and TiO2 nanopowders are synthesized by a conventional Sol-Gel method followed by high-temperature calcinations. The as-obtained products are characterized by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy-Dispersive X-Ray (EDX) spectroscopy. The XRD results reveal the crystallite size of the synthesized material. SEM images depict the formation of nanopowders and nanofibers. EDX studies confirmed the presence of Ti and O in the prepared samples.
Doaa M. Ragab;Nazik A. Elgindy
Abstract
Nanofibers fabrication is generating considerable interest in terms of their biomedical applications. Recent development in nanofibers fabrication techniques resulted in controlled manipulation of nanofibers characteristics, such as their high surface to volume ratio, high porosity and their ability ...
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Nanofibers fabrication is generating considerable interest in terms of their biomedical applications. Recent development in nanofibers fabrication techniques resulted in controlled manipulation of nanofibers characteristics, such as their high surface to volume ratio, high porosity and their ability to encapsulate bioactive molecules. Development of biocompatible, polymer coated nanofibers can also provide an optimal environment for cell adhesion, proliferation and differentiation. This paper presents an overview on different applied techniques for nanofibers fabrication, in addition to the process variables to tailor their physico-chemical characteristics. Furthermore, the current review sheds a new light on the application of nanofibers on treatment of diabetic foot ulcers and artificial skin reconstruction.
Sandeep Kumar Singh Patel; Khemchand Dewangan; Simant Kumar Srivastav; Narendra Kumar Verma; Paramananda Jena; Ashish Kumar Singh; N. S. Gajbhiye
Abstract
One-dimensional α-MoO3 nanofibers of 280–320 nm diameters were synthesized by a hydrothermal method. The morphologies and compositions of as-synthesized α-MoO3 nanofibers have been characterized by X-ray powder diffraction, Raman spectroscopy, and field-emission scanning electron microscopy. ...
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One-dimensional α-MoO3 nanofibers of 280–320 nm diameters were synthesized by a hydrothermal method. The morphologies and compositions of as-synthesized α-MoO3 nanofibers have been characterized by X-ray powder diffraction, Raman spectroscopy, and field-emission scanning electron microscopy. X-ray photoelectron spectroscopy showed the predominantly 6+ oxidation state with a small percentage of reduced δ+ (5 < δ < 6) oxidation state. The field-emission properties of α-MoO3 nanofibers show a lower turn-on electric field of 2.48 V µm -1 and threshold electric field of 3.10 V µm -1 . The results suggest that the α-MoO3 nanofibers are promising candidate for efficient and high-performance field-emission devices.
Rickard Andersson; Amin M. Saleem; Ioanna Savva; Theodora Krasia-Christoforou; Peter Enoksson; Vincent Desmaris
Abstract
Carbon nanostructures are of great interest for a variety of applications, but their current processing throughput limits their industrial full scale deployment. This paper presents a cost effective and simple fabrication process, where vertically aligned carbon nanofibers are grown using DC-PECVD at ...
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Carbon nanostructures are of great interest for a variety of applications, but their current processing throughput limits their industrial full scale deployment. This paper presents a cost effective and simple fabrication process, where vertically aligned carbon nanofibers are grown using DC-PECVD at CMOS compatible temperatures from catalytic nanoparticles, spin-coated from stable polymer-nanoparticle colloidal suspensions. Two different catalysts, Co and Cu, are investigated by growing carbon nanofibers at temperatures ranging from 390°C to 550°C, using suspensions with various concentrations of nanoparticles. The length and morphology of the grown nanofibers are examined using SEM and the electrical properties are investigated using electrochemical measurements on samples arranged as supercapacitor devices. Vertically aligned CNFs are successfully grown from both types of catalyst. The Co-derived fibers are long and arranged in a denser carpet-like structure, while the Cu-derived fibers are shorter and in a sparser formation of free-standing individual fibers. All electrochemical measurements show typical supercapacitor behaviour even at high scan rates of 200 mVs -1 , with the fibers grown from Co showing great increase in capacitance over the bare chip reference device, including the samples grown at 390°C.
Divya P. R; P. M. Sabura Begum; Rani Joseph; Indu Sebastian
Abstract
Herein, we have prepared Polyaniline (PANI) nanofibers by interfacial polymerization in the presence of co-oxidant and surfactant. The additives are found to have a profound impact on the polymers morphology and improved room temperature conductivity. It was found that PANI nanofibers prepared in the ...
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Herein, we have prepared Polyaniline (PANI) nanofibers by interfacial polymerization in the presence of co-oxidant and surfactant. The additives are found to have a profound impact on the polymers morphology and improved room temperature conductivity. It was found that PANI nanofibers prepared in the presence of aqueous sodium hypochlorite solution (NaOCl) and cetyl trimethyl ammonium bromide (CTAB) were of shorter diameter (30 nm) and high conductivity (6.59Scm -1 ) than those formed in the absence of those chemicals. The diameter of the fibers was intricately tuned by changing the ratio of NaOCl to aniline. The effect of co-oxidant and surfactant concentration in the nanofibers has been investigated with the help of SEM, IR, XRD, UV and conductivity studies. A comparative investigation with other surfactant sodium dodecyl sulphate (SDS) has been done and the variations in diameter were noted. We also studied the third-order optical nonlinearity and optical limiting properties of polyaniline nanofibers using a single-beam z-scan technique. The experiments were performed with a Nd-YAG laser at wavelength of 532 nm The mechanism behind nonlinear absorption could be predicted as two photon absorption. The results show that the polyaniline nanofibers have useful applications in futuristic nonlinear optics.
Javier Macossay; Faheem A Sheikh; Hassan Ahmad; Hern Kim; Gary L Bowlin
Abstract
Tissue engineering is a multidisciplinary field that has evolved in various dimensions in recent years. One of the main aspects in this field is the proper adjustment and final compatibility of implants at the target site of surgery. For this purpose, it is desired to have the materials fabricated at ...
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Tissue engineering is a multidisciplinary field that has evolved in various dimensions in recent years. One of the main aspects in this field is the proper adjustment and final compatibility of implants at the target site of surgery. For this purpose, it is desired to have the materials fabricated at the nanometer scale, since these dimensions will ultimately accelerate the fixation of implants at the cellular level. In this study, electrospun polyurethane nanofibers and their analogous nanofibers containing MWCNTs are introduced for tissue engineering applications. Since MWCNTs agglomerate to form bundles, a high intensity sonication procedure was used to disperse them, followed by electrospinning the polymer solutions that contained these previously dispersed MWCNTs. Characterization of the produced nanofibers has confirmed production of different non-woven mats, which include random, semi-aligned and mostly aligned patterns. A simultaneous and comparative study was conducted on the nanofibers with respect to their thermal stability, mechanical properties and biocompatibility. Results indicate that the mostly aligned nanofibers pattern presents higher thermal stability, mechanical properties, and biocompatibility. Furthermore, incorporation of MWCNTs among the different arrangements significantly improved the mechanical properties and cell alignment along the nanofibers.
Ashish Gupta; Deoram V. Nandanwar; Sanjay R. Dhakate
Abstract
Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis ...
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Zinc oxide (ZnO) nanoparticles, self-assembled in the form of one dimensional ZnO nanofibers were synthesized using electrospinning technique from solution of polyvinyl alcohol (PVA) and zinc acetate followed by calcination at 600°C in oxidizing environment. Scanning Electron Microscope (SEM) analysis demonstrates that morphology of ZnO nanofibers having rough surface and corresponding Energy Dispersive Spectrometry (EDAX) confirmed the Zn: O atomic ratio approximately in 50:50. Transmission electron microscopy (TEM) images clearly demonstrate the rough morphology is due to the self-assembling of ZnO nanoparticles having diameter approximately 50nm. X-ray Diffraction (XRD) reveals the polycrystalline structure and Raman spectra show some shifts in phonon modes. The PL graph show exceptional emission at 342nm due to band-band transition. Under solar radiations as produced ZnO nanofibers degrades the 99% of 25ppm acid fuchsine which proven through UV spectra when compared to blank dye solution. This shows that natural solar radiations are sufficient to excite theses self-assembled high surface area ZnO nanofibers to show its photocatalytic activity.
Damanpreet Kaur; Nahar Singh;Sanjay R. Dhakate; Ashish Gupta
Abstract
The objective of the present investigation is to deliver antiemetic GH (Granisetron hydrochloride) drug to cancer patient through nanofibers transdermal patch to overcome the problem of chemotherapy induced post-operative side effects like nausea and vomiting. The biodegradable poly vinylalcohol (PVA) ...
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The objective of the present investigation is to deliver antiemetic GH (Granisetron hydrochloride) drug to cancer patient through nanofibers transdermal patch to overcome the problem of chemotherapy induced post-operative side effects like nausea and vomiting. The biodegradable poly vinylalcohol (PVA) and polyvinyl pyrrolidone (PVP) electrospun composite nanofiber based transdermal patch was developed and anti-emetic drug was loaded by active loading in it. The in-vitro drug release from nanofibers patch demonstrates that there is a controlled release pattern of the drug and release rate is varying with PVP content in the composite nanofiber patch. Also from the data of cumulative drug permeation and steady state flux demonstrates that rate of drug release through membrane and permeation across skin increases with increasing concentration of PVP. The drug release follows Higuchi model of kinetics. While marketed drug tablet follows the zero order kinetic model of drug release. The regression values obtained for both the formulations lie in the range of 0.9484 – 0.951 which suggests the mechanism of drug release is due to the diffusion of embedded drug molecule and erosion of polymer from nanofiber an aqueous medium. Thus the present investigation gives impetus to work in the direction of delivering anti-emetic drug through nanofibers transdermal patch.
Suyog M. Pethe; Subhash B. Kondawar
Abstract
One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. Conducting polyaniline nanofibers can be synthesized by various methods. In this paper, we report the ...
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One dimensional conducting polymer nanostructures have been the focus of quite extensive studies worldwide due to their high aspect ratio, high porosity apart from high surface area to volume ratio. Conducting polyaniline nanofibers can be synthesized by various methods. In this paper, we report the preparation of polyaniline nanofibers with an average diameter of 40–70 nm by two different simple approach rapid mixing and interfacial polymerization. The key to producing polyaniline nanofibers is to suppress secondary growth. Based on this, interfacial polymerization and rapidly mixed reactions have been developed that can readily produce nanofibers by slightly modifying the conventional chemical synthesis of polyaniline without the need for any template or structural directing agent. Synthesized polyaniline (PANI) nanofibers were characterized by FTIR spectroscopy, X-ray diffraction, transmission electron microscopy for their structural and UV-Vis absorption spectroscopy for optical properties. Direct and indirect transition energy gaps were determined from their Tauc plots. The absorption spectra show a linear fit for the transition. Electrical properties of the synthesized polyaniline nanofibers have been studied and the Arrhenius plots of electrical conductivity for the samples synthesized by rapid mixing and interfacial polymerization method show an approximate equal in their activation energy. The results obtained from optical and electrical properties are well compared, correlated and explained with respect to interfacial and rapid mixing polymerization techniques.
Ganna Ungur; Jakub Hruza
Abstract
This research describes the fabrication of nanofibrous materials for the air purification with high filtration efficiency and catalytic properties to clean the air from solid particles and emissions of automobile's transport. The polyurethane (PU) nanofibers were modified by particles of SnO2 and ...
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This research describes the fabrication of nanofibrous materials for the air purification with high filtration efficiency and catalytic properties to clean the air from solid particles and emissions of automobile's transport. The polyurethane (PU) nanofibers were modified by particles of SnO2 and CrO2 in the ratio 95/5 to impart catalytic properties in the reaction with emission gases (CO, NOx).The modification process was provided by the introduction of metal’s oxide’s particles of different concentrations (1;2; 3; 4%) into the polymer solution. Reological properties and conductivity of the modified solutions were studied. The viscosity of solutions grew up gradually with increasing of SnO2/CrO2 concentrations. Fiber's samples were produced from modified solutions by the electorstatic fiber forming using Nanospider technology. The morphology of produced fibers was analysed by the Scanning Electron Microscopy (SEM). SEM pictures confirmed the smoothness of fibrous layer. The diameters of fibres were measured with the help of Lucie 32G computer software. The obtained results demonstrated increasing of average diameters of nanofibers for the concentration 1and 2% of catalysts in comparison with the pure PU samples. But fibers with 3 and 4% of SnO2/CrO2 particles showed the decreasing of average fiber diameters. The presence of catalyst on the nanofiber`s surface was proved by the method of Energy Dispersive Spectroscopy (EDS). The catalytic properties of produced nanolayers in the reaction with emission's gases were studied with the measurement setup consisting from the engine, a system of analyzers and UV lamp as a sourse of energy to activate the catalyst. All samples demonstrated good catalytic efficiency. The best result showed the sample of PU nanofibers with 3% of SnO2/CrO: the concentrations of CO and NOx reduced by 81% and 73% respectively. Produced samples are the promising materials for air-conditioning systems.
Yasir Ali; R G Sonkawade;A S Dhaliwal; Vijay Kumar
Abstract
We have electrochemically synthesized polyaniline nano fibers with optimized process parameters (viz. concentration of monomer and dopant, applied current density, deposition time, etc.) on ITO coated glass substrate. The nano fibers of polyaniline were subjected to UV Visible, SEM and Raman spectroscopy. ...
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We have electrochemically synthesized polyaniline nano fibers with optimized process parameters (viz. concentration of monomer and dopant, applied current density, deposition time, etc.) on ITO coated glass substrate. The nano fibers of polyaniline were subjected to UV Visible, SEM and Raman spectroscopy. UV Vis spectra show two prominent peaks at 317 and 418 nm, which confirm the presence of different forms of polyaniline. Raman spectra confirm the formation of polyaniline. SEM image of synthesized nano fibers showed a flower like structure with an isotropic growth rate.
Abstract
In the present contribution, it has been reported about the effect of solvent, solvent concentration, flow rate and applied voltage on the fabrication of electrospun polycarbonate (PC) nanofibers. The morphology of fibers was studied by optical and scanning electron microscope. It is observed that morphology ...
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In the present contribution, it has been reported about the effect of solvent, solvent concentration, flow rate and applied voltage on the fabrication of electrospun polycarbonate (PC) nanofibers. The morphology of fibers was studied by optical and scanning electron microscope. It is observed that morphology of fibers depends upon the concentration of PC or viscosity of the solution, vapor pressure and diffusion coefficient of solvent. In fact, when viscosity of the solution is very low, beads or droplets are formed instead of fibers. The same problem arises when the viscosity of the solution is too high due to high surface tension. In this case, jet formation will not be observed and the solution will coagulate at the tip of needle. Tetrahydrofuran (THF) easily diffuses with polymer, at higher concentration of PC and at higher flow rate of solution; fibers of micron size are formed because of high vapor pressure of THF. On the other hand, in case of mixed solvents (DMF and THF), by controlling processing parameters one can get fiber diameter up to 200 nm. The study of Differential Scanning Calorimetry (DSC) indicates that less amount of heat energy is absorbed during endothermic reaction and there is a slight increase in glass transition temperature of nanofibers. Thermogravimetric analysis (TGA) shows an increase in thermal stability of PC nanofibers by 40ºC as compared to PC granules. This is due to the alignment of PC polymeric chains during stretching and whipping that occurs while electro spinning process.