Electrospun Products Research Articles

Development of dense void-free electrospun SPEEK-Cloisite15A membrane for direct methanol fuel cell application: Optimization using response surface methodology

Response surface methodology (RSM) was utilized to design the experiments at the settings of solution concentration, voltage and the collector distance. It also imparted the evaluation of the significance of each parameter on the resultant physico chemicals (proton conductivity, methanol permeability and water uptake). The investigations were carried out in the two-variable process domains of several collector distances as applied voltage and the solution concentration were varied at a fixed polymer molecular weight. The result showed that all three factors were found statistically significant in the production of void free electrospun SPEEK/Cloisite membrane. All responses were correlated to these variables by using a second order polynomial function. The optimum condition for void free electrospun SPEEK/cloisite was at 0.17 wt% concentration with applied voltage of 22.15 kV and 18.83 cm distance from needle tip to screen collector.

Needleless Electrospinning Technology – An Entrepreneurial Perspective

Background/Objectives: Needleless electrospinning technology surmounts the shortcomings and bottlenecks of the conventional needle based electrospinning systems. Spinneret clogging and lower throughput in terms of productivity has been the setbacks of the conventional technology leading to fewer nanofibers based commercial products. Nanofiber based products finds a market in healthcare, energy and defence. Proof of concept leading to lab level prototype scaling up into industrial level of nanofiber production units is the focus of this paper. Methodology/Analysis: A simple search in the scopus web portal with a keyword ‘electrospinning’ resulted in 16,272 publications as of date. Same search for patent in US patent office portal resulted in 1939 granted patent documents. A comparison of years of technology time cycle (110 years), publications (16,272) and granted patents (1939) with the companies (31) working on electrospun products was made. Findings: Bubble, hollow tube, roller, wire based and slit-surface needleless electrospinning units are discussed on the basis of entrepreneurial product cycle of prototype development translating into commercial units. Nanofiber production at a mean diameter of 140 nm at commercial level using Poly (ethylene) oxide for Nano Drug Delivery Systems (NDDS) by wire based free surface electrospinning has been analysed. Novelty/Improvements: The analysis proves an entrepreneurial approach in the area of electrospinning as evidenced by number of patents match ups or exceeds publications in some region and also depicts its futuristic demand in several areas including healthcare and energy sectors.

Synthesis, Morphology Control and Electromagnetic Wave Absorption Properties of Electrospun FeCo Alloy Nanofibers.

Recently, increasing interest has been focused on one-dimensional (1 D) magnetic nanomaterials that have significant anisotropic electromagnetic parameters and size effects that can be used to achieve improved shielding efficiency. In this study, the simple, low-cost and scalable synthesis of FeCo nanofibers is demonstrated by combining an electrospinning process with sequential thermal treatment involving calcination in air followed by reduction in H2 atmosphere. A citric acid has an influence on the morphology of the electrospun product. The as-spun precursor nanofibers are transformed into CoFe2O4 and FeCo phases through the sequential thermal treatment while maintaining the fibrous shapes. To evaluate the electromagnetic (EM) wave-absorbing abilities of the FeCo nanofibers, epoxy matrix composites with the nanofibers are fabricated. The composites show excellent EM wave absorption properties where the power loss of the FeCo nanofibers increased to 20 GHz without any degradation.

Generation of multihollow structured poly(methyl methacrylate) fibers by electrospinning under pressurized CO2

Electrospinning is one of the simple techniques for the production of polymer nano‐microfibers. In this study, hollow fibers from poly(methyl methacrylate) (PMMA) were formed by electrospinning under pressurized carbon dioxide (CO2) in a single processing step. The experiments were conducted at temperatures and pressures in the range 27–37°C and 4–6 MPa, respectively. At 5 MPa, CO2 seemed to have enough affinity to dissolve a portion of dichloromethane (DCM) to assist its evaporation. Under subcritical CO2, electrospun products with hollow core fibers having diameters of 4–16 μm were generated. The results confirmed that the change of operating parameters had a strong influence on the morphologies (crack or hollows) of the electrospun products. This study demonstrated that this process offers the possibility that electrospinning under pressurized CO2 will become an essential and useful method for the generation of polymer structures with hollow interiors. POLYM. ENG. SCI., 56:752–759, 2016. © 2016 Society of Plastics Engineers

Three-Dimensional Model for Electrospinning Processes in Controlled Gas Counterflow.

We study the effects of a controlled gas flow on the dynamics of electrified jets in the electrospinning process. The main idea is to model the air drag effects of the gas flow by using a nonlinear Langevin-like approach. The model is employed to investigate the dynamics of electrified polymer jets at different conditions of air drag force, showing that a controlled gas counterflow can lead to a decrease of the average diameter of electrospun fibers, and potentially to an improvement of the quality of electrospun products. We probe the influence of air drag effects on the bending instabilities of the jet and on its angular fluctuations during the process. The insights provided by this study might prove useful for the design of future electrospinning experiments and polymer nanofiber materials.

Electrospun Herbal Extract Derived Polymer Nanocomposites for Medical Applications

Herbal plants have been used in medicine since ancient times due to their health benefits. The research in this field continues to reveal advantages of these plants such as antibacterial activity against multidrug-resistant bacteria and possibility to integrate extracts in fibers by electrospinning. Electrospinning is a simple, yet versatile method of creating polymer-based nanofiber web, which can be used for wound dressings, tissue engineering and drug delivery systems. In production of electrospun nanofibers a solution of biocompatible polymer and a plant extract is needed. Therefore exploration of such composition ingredients is important.

The use of different alumina fillers for improvement of the mechanical properties of hybrid PMMA composites

Abstract Alumina fillers having different morphologies were used for reinforcement of PMMA-based composite materials. The employed fillers had the same chemical composition but morphologically were spherical nanoparticles, whiskers and an electrospun product that was composed of micro-sized mostly spherical particles and nanofibers. The electrospun product was obtained from aluminum chloride hydroxide/PVA/water solution. All fillers were added without surface treatment and mechanical characteristics of obtained composites were determined using dynamic mechanical analysis (DMA) and nanoindentation. From the nanoindentation results, the reduced elastic modulus for the obtained specimens using 3 wt.% of electrospun product was 134% of the one obtained with the polymer alone and the hardness was improved to 157.8% compared to the polymer without any additive. DMA shows that the storage modulus at room temperature was twice that of the polymer alone.

Effect of oil on the morphology and photocatalysis of emulsion electrospun titanium dioxide nanomaterials

The effect of different oil on morphologies of emulsion electrospun products has been systematically studied. High photocatalytic degradation performed titanium dioxide (TiO2) nanomaterials with diverse morphologies, including nanoparticles, nanofibers, necklace-like nanofibers, porous nanofibers and surface rough nanotubes were prepared based on different water/oil phase separation processes due to distinctive properties of oils. The crystallinity and morphology of as-prepared nanomaterials were characterized by XRD and SEM, the optical absorption property was analyzed by UV–Visual spectrophotometer, N2 adsorption–desorption was carried to measure the micro-structures and pores distribution of obtained nanomaterials. The photocatalytic activities of as fabricated nanostructures were evaluated by the degradation of Rhodamine B (RhB) under illumination of a xenon lamp as light source. The results indicated that the different nanostructure can be obtained easily by changing the types of oil added into electrospun precursor solutions, and photocatalytic studies indicated that almost all of samples prepared by oil added precursors showed improved photocatalytic activities compared with their traditional counterpart. Our systematic study in this work implied that emulsion electrospinning is a simple and feasible method to prepare nanomaterials with diverse morphologies, which can be used in fabricating other semiconductor-based nanomaterials.

Morphological evolution from porous nanofibers to rice like nanobeans

Polycaprolactone/Polyethylene oxide (PCL/PEO) blends with different morphologies are prepared by electrospinning, and the porous PCL structures are obtained by selective removal of the PEO phase through water treatment. Morphology of the electrospun products evolves from the nanofiber to the rice like nanobeans by controlling the concentration of the blend polymer solution. Nanofiber is obtained at a high solution concentration, and the porosity and diameter of the nanofibers could be tuned by adjusting the PCL content in the blend solution. The needle like materials are present with decreasing solution concentration, and rice like nanobeans are observed with further decrease of the concentration. The decreased macromolecular entanglement is responsible for such morphology evolution.

Electrospun multifunctional tissue engineering scaffolds

Tissue engineering holds great promises in providing successful treatments of human body tissue loss that current methods are unable to treat or unable to achieve satisfactory clinical outcomes. In scaffold-based tissue engineering, a highperformance scaffold underpins the success of a tissue engineering strategy and a major direction in the field is to create multifunctional tissue engineering scaffolds for enhanced biological performance and for regenerating complex body tissues. Electrospinning can produce nanofibrous scaffolds that are highly desirable for tissue engineering. The enormous interest in electrospinning and electrospun fibrous structures by the science, engineering and medical communities has led to various developments of the electrospinning technology and wide investigations of electrospun products in many industries, including biomedical engineering, over the past two decades. It is now possible to create novel, multicomponent tissue engineering scaffolds with multiple functions. This article provides a concise review of recent advances in the R & D of electrospun multifunctional tissue engineering scaffolds. It also presents our philosophy and research in the designing and fabrication of electrospun multicomponent scaffolds with multiple functions.

Electrospun Nanomaterials: Biotechnology, Food, Water, Environment, and Energy

Over the past decade, electrospinning and electrospraying techniques have become affordable platform techniques for growing numbers of students, researchers, academics, and businesses around the world, producing organic and inorganic nanofibres and nanoparticles for a range of purposes. This review illustrates various advances in the science and engineering of electrospun nanomaterials and their applicability in meeting the growing needs within five crucial sectors: clean water, environment, energy, healthcare, and food. Although most of these sectors are principally dominated by synthetic polymer systems, the emergence of natural polymer and hybrid natural-synthetic electrospun polymer systems offers particular advantages. Current scientific and materials engineering advancements have resulted in highly competitive nanofibre, electrospun products, offering credible solutions to real-world applications.

The impact of relative humidity during electrospinning on the morphology and mechanical properties of nanofibers

Electrospinning is an efficient and flexible method for nanofiber production, but it is influenced by many systemic, process, and environmental parameters that govern the electrospun product morphology. This study systematically investigates the influence of relative humidity (RH) on the electrospinning process. The results showed that the morphology of the electrospun product (shape and diameter) can be manipulated with precise regulation of RH during electrospinning. Because the diameter of nanofibers correlates with their rigidity, it was shown that RH control can lead to manipulation of material mechanical properties. Finally, based on the solution's rheological parameter-namely, phase shift angle-we were able to predict the loss of homogenous nanofiber structure in correlation with RH conditions during electrospinning. This research addresses the mechanism of RH impact on the electrospinning process and offers the background to exploit it in order to better control nanomaterial properties and alter its applicability.

Industrial Upscaling of Electrospinning and Applications of Polymer Nanofibers: A Review

AbstractElectrospun nanofibers are extensively studied and their potential applications are largely demonstrated. Today, electrospinning equipment and technological solutions, and electrospun materials are rapidly moving to commercialization. Dedicated companies supply laboratory and industrial‐scale components and apparatus for electrospinning, and others commercialize electrospun products. This paper focuses on relevant technological approaches developed by research, which show perspectives for scaling‐up and for fulfilling requirements of industrial production in terms of throughput, accuracy, and functionality of the realized nanofibers. A critical analysis is provided about technological weakness and strength points in combination with expected challenges from the market. magnified image

Electrospun In2O3/α-Fe2O3 heterostructure nanotubes for highly sensitive gas sensor applications

In2O3/α-Fe2O3 (IFO) heterostructure nanotubes, with cubic-In2O3 nanocrystals randomly distributed on the surface of α-Fe2O3 nanotube-based backbones, were successfully prepared through a facile single-capillary electrospinning method. The morphologies of the resulting electrospun products were characterized by scanning electron microscopy and transmission electron microscopy. The crystal structures and components were determined by X-ray diffraction and energy-dispersive X-ray spectra, respectively. The results show that the morphology and structure of the products could be tailored by changing the content of indium nitrate in the precursor solutions and the calcination temperatures. Moreover, the IFO-0.1 (In/Fe = 1 : 9, molar ratio) nanotubes based sensor shows a high sensitivity to ethanol with a fast response/recovery time, and the performance is stable at a low operating temperature, which gives a potential application in ethanol gas sensors. A possible gas sensing mechanism based on the role of In2O3 in such a heterostructure is also discussed in detail.

Advanced Functional Polymers for Medicine

Advanced Functional Polymers for Medicine

Electrospinning short polymer micro-fibres with average aspect ratios in the range of 10–200

Ultra fine short fibres have a variety of applications. Short aligned fibres or a mixture of short and long fibres can reinforce brittle materials, alter the appearance, texture and durability of synthetic fibres, and adjust the strength, toughness and stiffness of a composite material. Among electrospun products, short fibres are usually produced by secondary processing of continuous as-spun fibres. However, this is not entirely straightforward or cost-effective due to the efficiency of the secondary process and the relatively low tensile strength of the electrospun ultrafine fibres. Besides, sub-micrometre size fibres with an average aspect ratio (AR) 3000 under the same spinning conditions.

Studies on the electrospun Nylon 6 nanofibers from polyelectrolyte solutions: 1. Effects of solution concentration and temperature

Polyelectrolyte solutions of Nylon 6 in 99 vol% formic acid were electrospun, and the effect of polymer concentration was studied. Using a laser device to locally heat the needle spinneret, the solution temperature was feasibly elevated up to 66 °C, and its effect on electrospinning was investigated as well. The microstructure of the as-spun products was characterized by several analytical techniques, including electron diffraction, differential scanning calorimetry (DSC) and wide-angle X-ray diffraction. Based on the solution rheology, the entanglement concentration (ce) was determined to be 1 wt%. To prepare bead-free fibers, the minimum polymer concentration was 8 ce, which was much higher than that (1.75–2.0 ce) required for conventional neutral solutions. Increasing the polymer concentration and/or solution temperature led to a gradual change of electrospun products from round fibers with major γ form crystals to ribbon-like fibers in possession of exclusive α form ones. For intermediate concentrations, nanowebs made of nanofibrils with diameters of 20–40 nm were seen. Thin ribbon-like fibers (ca. 40 nm thick) with nanowebs became the dominant products obtained from the 15 wt% solutions at high temperatures. The dramatic variations in morphological features and crystal modification could be thoroughly explained on the basis of the interplay between solvent evaporation at the jet surface and solvent diffusion in the liquid jet. DSC heating traces on the ribbon-like fibers exhibited an unusually high melting temperature of ∼235 °C, which is higher than the equilibrium melting temperature of Nylon 6 crystals of 232 °C.

Effect of Wet Post-Drawn on Structures and Properties of PA6/MWNTs Nanofiber Filaments

Electrospining technique is one of the hotest topics all over the world. The main form of the electrospun products is generally nonwoven fiber web with the poor mechanical properties. Consecutive PA6/MWNTs nanofiber filaments were successfully fabricated by an improved electrospining method. Peregal O was used as the bath to post-draw the as-spun filaments and the effects of draw ratio on their structures and properties were studied. The results show that with the increase of the draw ratio, the diameters of filament and fiber decrease; while the degree of orientation arrangement and crystallinity of the fibers is obviously improved and the breaking strength and initial modulus of the filaments increase. As the maximum draw ratio reaches 1.7, the breaking strength and initial modulus of the filament are 2.64 times and 4.2 times as compared to those of the control sample respectively.

Direct preparation of carbon nanotubes and nanobelts from polymer

Carbon nanotubes and carbon nanobelts were obtained via single-needle electrospinning on a basis of water-in-oil (W/O) emulsion technique, respectively. The morphology of electrospun products can be controlled by controlling the temperature of the collector during the electrospinning process. The mechanism of fabricating PAN nanotubes and nanobelts by emulsion electrospinning is discussed in detail. Transmission electron microscopy and scanning electron microscope results show that the carbon nanotubes (the inner diameter of 25-50 nm and the outer diameter of 50-100 nm) have a wall thickness of 10-50 nm, and the width and thickness of the nanobelts range from 100 to 300 nm, and 1 to 5 nm, respectively. A slight difference of bonding configuration of the carbon nanofibers, carbon nanotubes and carbon nanobelts is attributed partly to their different topological structures. The novel method is versatile and could be extended to the fabrication of various types of nanotubes and nanobelts.

Electrospinning of hydroxypropyl methylcellulose trimellitate solutions

Nonwoven fiber mats of hydroxypropyl methylcellulose trimellitate (HPMCT) with potential applications in controlled delivery of drugs and scaffolds for tissue cultures have been successfully fabricated by electrospinning of HPMCT solutions. The formation and diameters of HPMCT fibers fabricated by electrospinning were strongly influenced by the solvents employed, electrostatic field strength, and solution concentrations. The electrospun products generated from all HPMCT solutions with various weight-average molecular weights in methanol/dichloromethane (1:1) solvent consisted of clustered beads, while methanol/dichloromethane (1:5) solvent helped to generate smooth, uniform, submicron fibers. From the relationship between specific viscosity and molecular weight in different solvents, it could be concluded that methanol/dichloromethane (1:5) solvent enhanced the molecular entanglements, improved the viscosity of the solutions, thus helped to generate smooth fibers. When all the other variables were kept constant, the concentration range suitable for electrospinning was between 10% and 16% (wt), and the average fiber diameter increased as the concentration increased. When all the other variables were kept constant, the average fiber diameter decreased as the strength of the electrostatic field increased. Electrospinning the solutions of two compounds with similar structure, hydroxypropyl methylcellulose phthalate (HPMCP) and HPMCT, we found that the fibers electrospun from HPMCP were thicker than that from HPMCT, which is attributed to the fact that the solution’s conductivity of HPMCT (containing two free carboxyl groups) is higher than that of HPMCP (containing only one free carboxyl group).