Nanofiber Manufacturing Research Articles

Electrospun nanofibers: role of nanofibers in water remediation and effect of experimental variables on their nano topography and application processes

A comprehensive review on electrospun nanofibers: an insight into the latest solutions provided by the scientific community for large scale manufacturing of nanofibers and the role of nanofibers in water remediation.

Robust Nanofiber Films Prepared by Electro‐Microfluidic Spinning for Flexible Highly Stable Quantum‐Dot Displays

AbstractQuantum dot (QD)‐based liquid crystal displays (LCDs) are emerging as a new generation of LCDs due to their good performance. However, the QD fluorescent materials in LCDs are vulnerable to water and high temperatures, severely limiting their practical and long‐term use. Here, flexible and ultrastable QD‐based color‐converting films for LCD backlights are fabricated using robust poly(styrene‐methyl‐methacrylate‐acrylic acid) (poly(St‐MMA‐AA)) nanoparticle/polyamide 66 nanofiber (NPs@PA66) film with unique fiber–particle–fiber microstructure as protective substrate. Through an emerging strategy called electro‐microfluidic spinning technology (EMST), the nanofiber film not only exhibits excellent flexibility but also remarkably improves the mechanical property via the in situ particle‐mediated enhancement mechanism. An LCD backlight using the NPs@PA66 nanofiber film as QD loading substrate shows a wide color gamut of 116% and long‐term fluorescence stability under high temperature of 200 °C. More importantly, the fluorescence lifetime of NPs@PA66/QDs backlight reaches up to ≈64500 h, ≈22 times higher than that using encapsulated sandwiched polyethylene terephthalate (PET) QD film. These findings offer a promising method toward high‐strength nanofiber manufacturing, high‐stability flexible electronics and optoelectronic display devices.

A Brief Review of Electrospinning of Polymer Nanofibers: History and Main Applications

Electrospinning is an intensely facile methodology for the precise manufacturing of polymer nanofibers by manipulation of electrostatic force, which stunts like a driving force. In this technique, fibers produced with a diameter range between 50 to 500 nm. Two practices are made up by the scientists for electrospinning of versatile polymer. Polymers can be electrospun into ultrafine fibers in solvent solution or melt form. Tremendous progress had been made in this field in the past, and numerous applications were inaugurated. It’s a field of nanotechnology which rapidly growing due to enormous potential in creating novel applications regarding morphologies, materials structure, surface area, porosity, and Reinforcement in nanocomposite development. Fibers can be assembled in the form of nonwoven, aligned, patterned, random three-dimensional structures and sub-micron fibers. Many complications faced during electrospinning, for example, control the morphology and structure of Nanofibers, analyze surface functionality, and assembling strategies for various polymers. We need to find out various parameters for accurate fiber assembly. Here we briefly review the evolution activities in the field of electrospinning, understand its process, polymeric structure, property characterization, technology frailty, research provocations, future expectations, and resourceful applications.

Preparation of polymeric nanofibers via immersion electrospinning

Electrospinning is a simple and highly versatile method in manufacturing nanoscale fibers from a wide range of materials including metals, ceramics, and polymers. However, conventional electrospinning, in some applications of nanofiber production especially from water-insoluble polymers, could be considered as a harmful process. Since in traditional solution electrospinning nanofibers are formed through the evaporation of volatile and toxic solvents, which produces harmful gas and leads to environmental pollution. The accompanying pollution becomes more serious when it comes to large-scale manufacturing of nanofibers via electrospinning. Here, we apply a greener electrospinning method coined as Immersion Electrospinning (I-ESP) that applies phase separation to solidify spinning jets into nanofibers rather than solvent volatilization. In this study, I-ESP has been successfully exploited to fabricate nanofibers from poly(vinyl alcohol), poly(vinylidene fluoride), cellulose acetate, and poly(acrylic acid) with the hexane coagulation bath. The influence of polymer solution properties and coagulation bath composition on the morphology of nanofibers has been investigated.

Vancomycin-loaded electrospun polycaprolactone/nano-hydroxyapatite membrane for the treatment of blood infections

Nowadays, because of the resistance of bacteria to antibiotics, researchers are trying to make new antibiotics or sometimes even bring them back into the treatment cycle so that they could eliminate the bacteria’s resistance. On the other hand, the use of nanofibers has become widespread in many fields for their unique properties and convenient design. The present study focuses on the production of hydrophobic nanofibers to absorb the bacteria and their toxins from the bloodstream that contains the infection. Many bacterial surfaces have hydrophobic surfactant properties due to hydrophobic surface protein. According to the principle of binding two hydrophobic molecules to each other in an aqueous medium, the nanofibers are designed to physically absorb the bacteria. The use of antibiotics in the study can remove some unattached bacteria. In addition, using nanofiber manufacturing techniques can reduce the resistance of bacteria to antibiotics. The construction of the desired membrane can be used in subsequent studies as a replacement membrane for dialysis filters.

Investigation of Sound Absorption Characteristics of Polypropylene Nanofiber Nonwoven Fabric Focusing on Flow Resistance in Biot Acoustic Parameters

We proposed a novel nanofiber manufacturing technology by melt-blowing process. In the present report, we focused on manufactured polypropylene nanofiber nonwoven fabric as a novel sound absorbing material, measuring its Biot acoustic parameters, and also performed its CFD (Computational Fluid Dynamics)analysis to discuss flow resistance in them. Especially, we looked at the influence of the gap ratio (the ratio of the fiber gab between fibers and fiber diameter, which was related to the porosity), Knudsen number and the thermal characteristic length on the sound absorption coefficient and the flow resistance. As a result, it can be seen that the sound absorption coefficient and the flow resistance are greatly affected by the gap between the fibers. Moreover, the gap ratio and the thermal characteristic length are found to be essential parameters under the constant gap between fibers.

A Review on Electro-spun Nanofibers for Air Pollution Control

These days air pollution has emerge as greater severe and commenced to have a dramatic impact at the fitness of people in many big towns. Usually, out of doors personal protection, together with commercial masks cannot successfully save you the inhalation of much pollution. Specific remember (PM) pollutants are specially a critical risk to human fitness. Here we introduce a brand-new green air filtration materials and methodologies that can be used for outside in addition to in Indoor air filtration. Sub-microfibers and nanofibers membranes have an excessive surface to extent ratio which makes them suitable for diverse programs such as environmental remediation and filtration, strength production and garage, digital optical sensors, tissue engineering and drug shipping. The fast file affords an outline of cutting-edge situation of nanofibers produced using electrospinning approach and the one-of-a-kind polymers used for the manufacturing of nanofibers and the improvement procedures.

High‐efficiency preparation of polypropylene nanofiber by melt differential centrifugal electrospinning

ABSTRACTMelt differential centrifugal electrospinning (MDCE) method is proposed by integrating the advantages of centrifugal spinning and melt differential electrospinning, including high efficiency, solvent‐free, multiple jets formation from nozzle‐less spinning system, and small diameter. A mathematical model of jet diameter in MDCE is established. An orthogonal experiment is carried out to explore the effects of main processing parameters on the average diameter and the diameter standard deviation of the prepared fibers. Ultimately, polypropylene (PP) nanofibers with an average diameter of 790 nm are successfully prepared in a higher flow rate of 124.26 g h−1 than that of other methods. The X‐ray diffraction and differential scanning calorimeter indicate that the introduction of high‐voltage electrostatic field in centrifugal spinning contribute to the crystal orientation of the PP molecular chain. Therefore, tensile mechanical strength is enhanced as the increase of the loading voltage. MDCE may provide an efficient and eco‐friendly method for nanofiber manufacturing in the future. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48299.

Scalable manufacturing and applications of nanofibers

Schematic illustration of polymer, metallic and ceramic nanofibers from electrospinning, blowspinning, centrifugal spinning and drawspinning. Images were modified with permission from Refs. [29,31,42,51,77,97,102,118,136]. Nanofibers have been developed rapidly owing to their novel properties and wide applications. Scalable manufacturing of nanofibers is important for future applications. This paper provides a brief review on current research activities dealing with the synthesis of nanofibers by solution spinning methods, including electrospinning, blowspinning, centrifugal spinning, and drawspinning. Among these methods, electrospinning is the most widely studied and it allows the production of fibers with the smallest average diameters among the four technologies. Blowspinning and centrifugal spinning possess the highest productivity among the spinning techniques owing to their high efficient driving force. Drawspinning is suitable for producing ultra-long single nanofiber or nanofiber mesh, although it presents the lowest productivity among these methods. In addition, this paper describes some scalable applications of nanofibers in various areas, including filters, flexible electronics, and compressive ceramic thermal insulators.

Carbon Nanofibers Coated with Silicon/Calcium-Based Compounds for Medical Application

The aim of this work was to develop a method for the manufacture of carbon nanofibers in the form of mats containing silicon and calcium compounds with potential biomedical application. Carbon nanofibers (ECNF) were prepared from the electrospun polyacrylonitrile (PAN) nanofibers. The electrospun polymer nanofibers were heat treated up to 1000°C to obtain carbon nanofibers. The surface of ECNF was covered with a silica-calcium sol (ECNF+Si/Ca) by dip-coating technique followed by the stabilization process. Both types of carbon nanofibers, i.e., the as-received and covered with the sol, were tested to confirm their osteoconductive properties. Biological tests were performed, including genotoxicity, cytotoxicity, and alkaline phosphatase (ALP) activity. Morphology of adhering cells to nanofiber surface was described. The nanofibers were subjected to a bioactivity test in contact with SBF artificial plasma. Biological tests have revealed that the nanofiber-modified ECNF+Si/Ca in contact with osteoblast cells were biocompatible, and the level of cytotoxicity was lower compared to the control. The ALP activity of the modified nanofibers was higher than nonmodified nanofibers and indicates potential applications of such carbon materials in the form of mats as a substrate for bone tissue regeneration.

Structural aspects on the manufacturing of cellulose nanofibers from wood pulp fibers

The exact mechanism behind the disintegration of chemical pulp fiber into cellulose nanofibers is poorly understood. In this study, samples were subjected to various homogenization cycles, indicating that the mechanism is a stepwise process. In the earlier stages of the mechanical process, a large amount of macrofibrils were created as the larger structures disappeared. Upon mechanical treatment these macrofibrils disappeared despite the increasing yield of cellulose nanofibers. The proposed model expands the understanding of the disintegration pathway and may provide additional insight as to how wood cells are converted into microfibrils.

Fine liquid blowing: A high Reynolds number, high production rate nanofiber manufacturing technique

ABSTRACTA novel gas‐assisted jetting process, term fine liquid blowing, is used to improve the production rate of making nanofiber from polymer solution. A high‐velocity gas stream is introduced through a central protruding core needle, while a liquid is introduce via an adjacent satellite needle. This arrangement avoids passing the high‐velocity gas over the surface of the slow flowing liquid and results in the stable acceleration of the liquid flow on its approach to the tip of the core needle, where it interacts with the high‐velocity gas, initiating numerous liquid jets at elevated Reynolds numbers of up to more than 800. The method was used to produce poly (vinyl alcohol) nonwoven fiber mats at polymer solution feed rates of up to 900 mL h, surpassing other conventional methods. The produced fibers were of diameters ranging from 96 to 430 nm. Over the tested range, polymer flow rate did not show significant influence on the resulting fiber diameter. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47384.

Electrospinning on a plucked string

Preparation of high-quality nanofibers by electrospinning with low applied voltage and industrial scales remains challenging. A novel differential electrospinning technology for nanofiber preparation was proposed, with which multiple jets are generated from the string by plucking. The spinning principles were investigated, and the operation parameters were optimized. Results showed that lower threshold electric field was required for jets generation by plucked string electrospinning compared with the conventional needleless electrospinning. The finest average diameter of nanofibers with a narrow distribution range of 143 ± 16 nm was obtained at an applied voltage of 25 kV, a PVA concentration of 8 wt%, a rotational speed of 150 rpm and a spinning distance of 7 cm. The maximum yield for single string was as high as 2.64 g h−1 at a PVA concentration of 12 wt%. It was demonstrated that the proposed technology is feasible for manufacturing of nanofibers with lower voltage and high productivity as the string could be modularly extended.

Mechanisms of Transformation of Bulk Aluminum-Lithium Alloys to Aluminum Metal-Organic Nanowires.

Fabrication and applications of lightweight, high load-bearing, thermally stable composite materials would benefit greatly from leveraging the high mechanical strength of ceramic nanowires (NWs) over conventional particles or micrometer-scale fibers. However, conventional synthesis routes to produce NWs are rather expensive. Recently we discovered a novel method to directly convert certain bulk bimetallic alloys to metal-organic NWs at ambient temperature and pressure. This method was demonstrated by a facile transformation of polycrystalline aluminum-lithium (AlLi) alloy particles to aluminum alkoxide NWs, which can be further transformed to mechanically robust aluminum oxide (Al2O3) NWs. However, the transformation mechanisms have not been clearly understood. Here, we conducted advanced materials characterization (via electron microscopy and nuclear magnetic resonance spectroscopies) and chemo-mechanical modeling to elucidate key physical and chemical mechanisms responsible for NWs formation. We further demonstrated that the content of Li metal in the AlLi alloy could be reduced to about 4 wt % without compromising the success of the NWs synthesis. This new mechanistic understanding may open new avenues for large-scale, low-cost manufacturing of NWs and nanofibers for a broad range of composites and flexible ceramic membranes.

Electrospun natural cellulose/polyacrylonitrile nanofiber: simulation and experimental study

In this paper, we report on the fabrication and characterization of cellulose/polyacrylonitrile (cellulose/PAN) nanofiber via the electrospinning technique. The effects of voltage and blending ratio on the morphology of the electrospun cellulose/PAN nanofibers are investigated. The electric field distribution of the nanofiber manufacturing system is simulated by using finite element method analysis. The results show that the morphology and diameters of the nanofiber are obviously affected with the change of the electric field and blending ratio. The surface morphology, chemical structural, thermal stability, mechanical property and wettability of the cellulose/PAN nanofibers with different blending ratios are evaluated systematically. The thermal stability and mechanical property of the cellulose/PAN nanofibers have a certain improvement compared with pure cellulose nanofiber. The wettability of cellulose/PAN nanofibers is better than that of ordinary medical gauze.

Trial Manufacture of Nanofibers Made from a Main-Chain Liquid-Crystalline Elastomer Composed of Bibenzoate Mesogens

Trial Manufacture of Nanofibers Made from a Main-Chain Liquid-Crystalline Elastomer Composed of Bibenzoate Mesogens

Recent Progress of Fabrication of Cell Scaffold by Electrospinning Technique for Articular Cartilage Tissue Engineering.

As a versatile nanofiber manufacturing technique, electrospinning has been widely employed for the fabrication of tissue engineering scaffolds. Since the structure of natural extracellular matrices varies substantially in different tissues, there has been growing awareness of the fact that the hierarchical 3D structure of scaffolds may affect intercellular interactions, material transportation, fluid flow, environmental stimulation, and so forth. Physical blending of the synthetic and natural polymers to form composite materials better mimics the composition and mechanical properties of natural tissues. Scaffolds with element gradient, such as growth factor gradient, have demonstrated good potentials to promote heterogeneous cell growth and differentiation. Compared to 2D scaffolds with limited thicknesses, 3D scaffolds have superior cell differentiation and development rate. The objective of this review paper is to review and discuss the recent trends of electrospinning strategies for cartilage tissue engineering, particularly the biomimetic, gradient, and 3D scaffolds, along with future prospects of potential clinical applications.

Obtention of Cellulose Acetate Nanofibers From Sugar Cane Bagasse

Cellulose is one of the oldest natural polymers, it is renewable, biodegradable, and can be derivatized to manufacture useful products. The electrospinning, a technique for the manufacture of nanofibers, has garnered attention in recent years due to its versatility and potential for applications in various fields such as biomedicine, tissue engineering andalso filtration. In this study, cellulose acetate fibers have been obtained by electrospinning. To achieve these results, the cellulose was initially obtained from the sugar-cane bagasse of local plantations in Moniquira, Boyaca, then cellulose was modified to obtain cellulose acetate, which has enhanced properties for electrospinning. Yarn parameters were determined, such as needle-manifold distance, flow rate, voltage and polymer concentration, among others. Instrumentalanalyses were carried out including Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). As a result, cellulose acetate fibers were obtained with an average diameter of 258 nm, with excellent properties such as temperature resistance. This was done in order to continue the work on nanofiber functionalization, as for example, cationization of cellulose and further addition ofreactive dyes.

A new approach to obtain cellulose nanocrystals and ethanol from eucalyptus cellulose pulp via the biochemical pathway.

The feasibility of integration of cellulosic ethanol production with the manufacture of cellulose nanofibers (CNF) and cellulose nanocrystals (CNC) was evaluated using eucalyptus cellulose pulp as feedstock and employing the biochemical route alone. For the enzymatic hydrolysis step, experimental central composite design (CCD) methodology was used as a tool to evaluate the effects of solids loading (SL) and enzymatic loading (EL) on glucose release and cellulose conversion. Glucose concentrations from 45 to 125 g/L were obtained after 24 h, with cellulose conversions from 35 to 96%. Validation of the statistical model was performed at SL of 20% and EL of 10 mg protein/g, which was defined by the desirability function as the optimum condition. The sugars released were used for the production of ethanol by Saccharomyces cerevisiae, resulting in 62.1 g/L ethanol after 8 h (yield of 95.5%). For all the CCD experimental conditions, the residual solids presented CNF characteristics. Moreover, the use of a new strategy with temperature reduction from 50 to 35°C after 24 h of enzymatic hydrolysis enabled CNC to be obtained after 144 h. The CNC showed a crystallinity index of 83%, length of 260 nm, diameter of 15 nm, and aspect ratio (L/D) of 15. These characteristics are suitable for many applications, such as reinforcement in polymeric materials and other lower volume higher value bio-based products. The findings indicate the viability of obtaining ethanol and CNC using the biochemical route exclusively, potentially contributing to the future implementation of forest biorefineries. © 2017 American Institute of Chemical Engineers Biotechnol. Prog., 33:1085-1095, 2017.

Design and Fabrication of Fibrous Nanomaterials Using Pull Spinning

The assembly of natural and synthetic polymers into fibrous nanomaterials has applications ranging from textiles, tissue engineering, photonics, and catalysis. However, rapid manufacturing of these materials is challenging, as the state of the art in nanofiber assembly remains limited by factors such as solution polarity, production rate, applied electric fields, or temperature. Here, the design and development of a rapid nanofiber manufacturing system termed pull spinning is described. Pull spinning is compact and portable, consisting of a high‐speed rotating bristle that dips into a polymer or protein reservoir and pulls a droplet from solution into a nanofiber. When multiple layers of nanofibers are collected, they form a nonwoven network whose composition, orientation, and function can be adapted to multiple applications. The capability of pull spinning to function as a rapid, point‐of‐use fiber manufacturing platform is demonstrated for both muscle tissue engineering and textile design.image