Nanofiber Nonwovens Research Articles

Flexible and cross-linked N, S co-doped carbon nanofiber nonwovens derived from coal liquefaction residue for high performance supercapacitors

Flexible and cross-linked N, S co-doped carbon nanofiber nonwovens derived from coal liquefaction residue for high performance supercapacitors

Polyethylenimine-Functionalized Nanofiber Nonwovens Electrospun from Cotton Cellulose for Wound Dressing with High Drug Loading and Sustained Release Properties.

Electrospun cellulose nanofiber nonwovens have shown promise in wound dressing owing to the highly interconnected pore structure, high hydrophilicity coupled with other coveted characteristics of biodegradability, biocompatibility and renewability. However, electrospun cellulose wound dressings with loaded drugs for better wound healing have been rarely reported. In this study, a novel wound dressing with a high drug loading capacity and sustained drug release properties was successfully fabricated via electropinning of cellulose followed by polyethylenimine (PEI)-functionalization. Remarkably, the grafted PEI chains on the surface of electrospun cellulose nanofibers provided numerous active amino groups, while the highly porous structure of nonwovens could be well retained after modification, which resulted in enhanced adsorption performance against the anionic drug of sodium salicylate (NaSA). More specifically, when immersed in 100 mg/L NaSA solution for 24 h, the as-prepared cellulose-PEI nonwoven displayed a multilayer adsorption behavior. And at the optimal pH of 3, a high drug loading capacity of 78 mg/g could be achieved, which was 20 times higher than that of pristine electrospun cellulose nonwoven. Furthermore, it was discovered that the NaSA-loaded cellulose-PEI could continuously release the drug for 12 h in simulated body fluid (SBF), indicating the versatility of cellulose-PEI as an advanced wound dressing with drug carrier functionalities.

Accelerated Endothelialization of Nanofibrous Scaffolds for Biomimetic Cardiovascular Implants.

Nanofiber nonwovens are highly promising to serve as biomimetic scaffolds for pioneering cardiac implants such as drug-eluting stent systems or heart valve prosthetics. For successful implant integration, rapid and homogeneous endothelialization is of utmost importance as it forms a hemocompatible surface. This study aims at physicochemical and biological evaluation of various electrospun polymer scaffolds, made of FDA approved medical-grade plastics. Human endothelial cells (EA.hy926) were examined for cell attachment, morphology, viability, as well as actin and PECAM 1 expression. The appraisal of the untreated poly-L-lactide (PLLA L210), poly-ε-caprolactone (PCL) and polyamide-6 (PA-6) nonwovens shows that the hydrophilicity (water contact angle > 80°) and surface free energy (<60 mN/m) is mostly insufficient for rapid cell colonization. Therefore, modification of the surface tension of nonpolar polymer scaffolds by plasma energy was initiated, leading to more than 60% increased wettability and improved colonization. Additionally, NH3-plasma surface functionalization resulted in a more physiological localization of cell–cell contact markers, promoting endothelialization on all polymeric surfaces, while fiber diameter remained unaltered. Our data indicates that hydrophobic nonwovens are often insufficient to mimic the native extracellular matrix but also that they can be easily adapted by targeted post-processing steps such as plasma treatment. The results achieved increase the understanding of cell–implant interactions of nanostructured polymer-based biomaterial surfaces in blood contact while also advocating for plasma technology to increase the surface energy of nonpolar biostable, as well as biodegradable polymer scaffolds. Thus, we highlight the potential of plasma-activated electrospun polymer scaffolds for the development of advanced cardiac implants.

Biocompatible and mechanically-reinforced tribopositive nanofiber mat for wearable and antifungal human kinetic-energy harvester based on wood-derived natural product

Developing sustainable and environmentally friendly energy harvester is of great interest for various applications, especially for wearable and body-attachable self-powered electronics. Here, a biocompatible, mechanically durable, and sustainable wood-derived triboelectric nanogenerator (wood-TENG) is fabricated and applied as a human kinetic-energy harvester, along with an antifungal activity against athlete's foot. The wood-TENG is composed of the wood-derived natural product, i.e., the root bark of Ulmus davidiana var. japonica and the biocompatible polymer, i.e., polycaprolactone (PCL). The incorporation of U. davidiana var. japonica in nonwoven PCL nanofiber (NF) mat not only enhances the mechanical properties of the wood-TENG, but also increases the surface energy of the NF mat, resulting in the highest energy harvesting efficiency as compared to those of other bio-TENGs. Various physicochemical characterizations, including Fourier transform infrared (FTIR), Kelvin probe force microscopy (KPFM), etc., are conducted to explore the tribopositivity of the NF mat. Thanks to the enhanced triboelectricity, our wood-TENG can generate a maximum output voltage of 80 V and show stable cyclic energy harvesting performance during 100,000 cycles.

TiO2-Based Nanofibrous Membranes for Environmental Protection.

Electrospinning is a unique technique that can be used to synthesize polymer and metal oxide nanofibers. In materials science, a very active field is represented by research on electrospun nanofibers. Fibrous membranes present fascinating features, such as a large surface area to volume ratio, excellent mechanical behavior, and a large surface area, which have many applications. Numerous techniques are available for the nanofiber’s synthesis, but electrospinning is presented as a simple process that allows one to obtain porous membranes containing smooth non-woven nanofibers. Titanium dioxide (TiO2) is the most widely used catalyst in photocatalytic degradation processes, it has advantages such as good photocatalytic activity, excellent chemical stability, low cost and non-toxicity. Thus, titanium dioxide (TiO2) is used in the synthesis of nanofibrous membranes that benefit experimental research by easy recyclability, excellent photocatalytic activity, high specific surface areas, and exhibiting stable hierarchical nanostructures. This article presents the synthesis of fiber membranes through the processes of electrospinning, coaxial electrospinning, electrospinning and electrospraying or electrospinning and precipitation. In addition to the synthesis of membranes, the recent progress of researchers emphasizing the efficiency of nanofiber photocatalytic membranes in removing pollutants from wastewater is also presented.

Vapor-phase glutaraldehyde crosslinked waste protein-based nanofiber nonwovens as an environmentally friendly wound dressing

Vapor-phase glutaraldehyde crosslinking was used to improve the performance of feather keratin/gelatin (FK/Ge) nanofiber nonwovens for potential use as wound dressings. Crosslinking was performed by placing the electrospun nonwovens in a glutaraldehyde vapor for different times (1.5, 3, 4.5, 6, and 9 h). Fourier-transform infrared spectroscopy and X-ray diffraction analysis revealed strong interactions between FK and Ge, and verified the crosslinking of FK/Ge molecular chains by glutaraldehyde. Fibers in the crosslinked nonwovens formed a compact and porous structure that promotes cell proliferation and growth. Further, a proper extent of crosslinking reaction can effectively improve the mechanical strength and water resistance of FK/Ge nanofiber nonwovens, while maintaining their water uptake and thermal degradation properties within an acceptable range. These improvements are attributed to the flexible control over the degree of vapor-phase crosslinking. In vitro tests demonstrated that the crosslinked samples not only lack cytotoxicity but also promote the rapid proliferation of human foreskin fibroblasts. These new crosslinked nanofiber nonwovens derived from waste materials are promising for wound repair and care.

Colloid Syringeless Electrospinning toward Nonwoven Nanofiber Web Containing a Massive Amount of Inorganic Fillers

AbstractColloidal electrospinning is identified as a powerful tool for the fabrication of nonwoven nanofiber webs with increased functionality by the introduction of functional fillers into the webs. However, the use of this method is still limited due to minimal material diversity, low concentration of fillers, difficulty in mass production, and process difficulties. In this paper, syringeless electrospinning is suggested as an excellent method for colloidal electrospinning. Since the polymeric solution is supplied from the container through rotating drums, this method is relatively free from the precipitation of fillers present in the polymeric solution. Syringeless electrospinning provides a higher production rate than needle‐based electrospinning with simple process control. The syringeless technique makes it possible to expand the scope of the method to various polymers and inorganic fillers with sufficiently high filler concentrations. Herein, nonwoven nanofiber webs with a diverse combination of polymers (polyacrylonitrile (PAN), thermoplastic polyurethane (TPU), and polyvinylpyrrolidone (PVP)) and fillers (silica, titania, zirconia, activated carbons, and metal‐organic framework (MOF) crystals) are presented. Nonwoven nanofiber webs comprising PAN and UiO‐66‐NH2 MOF crystal are prepared for detoxification of a nerve agent simulant, diisopropyl fluorophosphate (DFP), as a representative example of applications.

Boron‐containing nonwoven polymeric nanofiber mats as neutron shields in compact nuclear fusion reactors

Composite materials that contain thermally and chemically stable boron compounds are attractive candidates for applications that require high neutron absorption due to the large neutron absorption cross-section of boron. Electrospun polymer nanofibers have a unique volume-to-surface area, incorporating carbon and hydrogen atoms in their molecular structure that could moderate and thermalize incident neutrons. Nonwoven nanofibers could in turn reduce neutron scattering and increase neutron absorption by providing large surfaces and better atom economy in the shield materials. The expected high absorption will result from improved neutron interaction with high neutron absorbance hydrogen, carbon, and boron atoms in the nanofibers through increased specific surface area and atom economy. In this work, elemental boron-doped PVA polymeric nanofibers are produced for the first time to date for the application of neutron shielding. With the increasing demand for nuclear power generation and radiation therapies in medicine, the need for producing lightweight and flexible materials that could replace the traditional heavy metal/metal carbide-based shields is vital. Similarly, the need for flexible materials that could shield neutrons is also becoming critical for aerospace applications. The effect of boron content on the quality of fibers and neutron shielding capacity is evaluated by using an Am-Be neutron source. Characterization studies of produced nanofibers were carried out by SEM, TGA, FT-IR, and XPS analyses. Results have shown that PVA-based nanofibers doped with wt% 0.1 to 0.5 boron, having fiber diameter distribution between 60 and 330 nm range, could absorb up to 6% of neutron flux.

Laser microstructuring of elastin-gelatin-based biomedical materials

In recent years, efforts have been made to develop special wound dressings to improve the healing of chronic or large area wounds. Elastin-gelatin-based nonwovens and sponges are candidates for these applications. Such materials are absorbable and possess a microstructure which is appropriate for the growth of biological cells. While sponges are suitable to fill deeper wounds, nanofiber nonwovens can cover large-area skin defects. It is expected that by introducing microholes into nonwovens and sponges the drainage and the oxygen supply of the underlying tissue can be further improved. Ultrashort pulsed laser microstructuring of these delicate materials has been evaluated. Laser cutting and drilling process strategies and parameters have been found to treat the wound dressings without affecting their beneficial basic properties.

Fabrication of Electrospun Nanofibers Membrane for Emulsified Oil Removal from Oily Wastewater

The electrospun nanofibers membranes have gained considerable interest in water filtration applications. In this work, the fabrication and characterization of the electrospun polyacrylonitrile-based nonwoven nanofibers membrane are reported. Then, the membrane's performance and antifouling properties were evaluated in removing emulsified oil using a cross flow filtration system. The membranes were fabricated with different polyacrylonitrile (PAN) concentrations (8, 11, and 14 wt. %) in N, N-Dimethylformamide (DMF) solvent resulted in various average fiber sizes, porosity, contact angle, permeability, oil rejection, and antifouling properties. Analyses of surface morphology of the fabricated membranes before and after oil removal revealed increasing the fiber size, decreasing the fouling amount, and increasing the permeate flux. On the other hand, decreasing the fiber size resulting in increases the oil rejection. It was observed that 11 wt. % PAN based nonwoven nanofiber membrane was the optimum membrane for emulsified oil removal due to its good porosity, permeability with good oil rejection. In addition, fouled nonwoven nanofiber membrane cleaning was done by backwashing technique using warm distilled water which was effective in retaining the membrane permeability and oil rejection for 7 times. The obtained results confirmed an efficient performance of the fabricated nanofibers membrane for oil-water separation with oil rejection percentage of 92.5% and a permeate flux of 120 LMH.

Bicomponent PLA Nanofiber Nonwovens as Highly Efficient Filtration Media for Particulate Pollutants and Pathogens.

Herein, a novel form of bicomponent nanofiber membrane containing stereo-complex polylactic acid (SC-PLA) was successfully produced by the side-by-side electrospinning of Poly (L-lactic acid) (PLLA) and Poly (D-lactic acid) (PDLA). We demonstrate that through these environmentally sustainable materials, highly efficient nanofiber assemblies for filtration can be constructed at very low basis weight. The physical and morphological structure, crystalline structure, hydrophobicity, porous structure, and filtration performance of the fibrous membranes were thoroughly characterized. It was shown that the fabricated polylactic acid (PLA) side-by-side fiber membrane had the advantages of excellent hydrophobicity, small average pore size, high porosity, high filtration efficiency, low pressure drop as well as superior air permeability. At the very low basis weight of 1.1 g/m2, the filtration efficiency and pressure drop of the prepared side-by-side membrane reached 96.2% and 30 Pa, respectively. Overall, this biomass-based, biodegradable filtration material has the potential to replace the fossil fuel-based polypropylene commercial meltblown materials for the design and development in filtration, separation, biomedical, personal protection and other fields.

Polydopamine-Modified Electrospun Polyvinylidene Fluoride Nanofiber Based Flexible Polymer Gel Electrolyte for Highly Stable Dye-Sensitized Solar Cells.

To overcome the drawbacks of solvent evaporation and leakage from the liquid electrolyte in dye-sensitized solar cells (DSSCs), a polymer gel electrolyte (PGE), based on polydopamine (PDA)-modified electrospun polyvinylidene fluoride (PVDF) nanofibers, PDA@PVDF, was prepared and applied in quasi-solid DSSCs (QS-DSSCs). The PDA coating increased the wettability of the liquid electrolyte by improving the distribution of the ionic liquid electrolyte. This, in turn, enhanced the ion conductivity of the PGE as well as the stability of QS-DSSC. The PDA@PVDF nanofiber membrane exhibited a satisfactory ultimate tensile strength of 9.3 MPa with a failure elongation of 130%. Such high toughness provided excellent mechanical support for the PGE. Owing to the unique pore connected structure of nonwoven nanofibers as well as the reduced surface tension with the liquid electrolytes, the PGE-based QS-DSSC retained 95.7% of the short circuit current from the liquid-electrolyte-based DSSC and showed an energy conversion efficiency of 8.26%. No significant impacts were observed for the open-circuit voltage and fill factor. More importantly, the QS-DSSCs using PDA@PVDF-based PGE showed a significantly improved solar cell stability under both indoor and outdoor conditions.

Ultrathin fibre coatings on nanofibrous nonwovens by plasma enhanced chemical vapor deposition

Abstract For the generation of tailor-made polymer coatings on nanofibrous nonwovens plasma enhanced chemical vapor (PECVD) is a promising process, even for complex geometries. The plasma coatings can greatly improve their suitability for biomedical applications by optimising biocompatibility to the local needs, especially for cardiovascular disease treatments. Therein, wound healing and endothelialisation are important steps which are connected by a complex interaction. The monomers allylamine and hexamethyldisiloxane, as well as different process conditions were studied for the coating of nanofibrous thermoplastic silicone polycarbonate polyurethane (TSPCU) nonwovens. Aim of this study was to investigate the feasibility of plasma polymer coating under preservation of the nanofibrous morphological structure. Beside characterization of the nonwoven, biological evaluation with endothelial and fibroblast cells was performed. The prepared nonwoven samples support the feasibility of plasma coating under preservation of the nanofibrous structure. Also, different effects of the surfaces in contact with fibroblasts and endothelial cells could be observed.

Femtosecond laser structuring of permeable and resorbable biomaterial

Abstract Bioresorbable nanofiber nonwovens with their fascinating properties provide a wide range of potential biomedical applications. Modification of the material enables the adjustment of mechanical and biological characteristics depending on the desired application. Due to the nanosized fiber network, post-production structuring is very challenging. Within this study, we use femtosecond laser technology for structuring permeable and resorbable electrospun poly-L-lactide (PLLA) membranes. We show that this post-production process can be used without disturbing the fiber network near the structured areas. Furthermore, the modification of the water permeability and mechanical characteristics due to the laser structuring was investigated. The results prove femtosecond laser technology to be a promising method for the adjustment of the membrane properties and which in consequence can help to optimize cell adhesion, enable revascularization and open up applications of nanofiber membranes in personalized medicine.

Preparation and characterization of the advanced alginate-based nanofibrous nonwoven using EDC/NHS coupling agent by electrospinning

Electrospinning has become the most studied technique in the production of nanofibrous materials. Sodium alginate-based (SAlg) nanofibrous material is used widely in many application fields due to its excellent properties, but it needs to combine with synthetic polymers, such as polyvinyl alcohol (PVA), to enhance its electrospinability. The electrospun SAlg/PVA nonwoven could be used in many fields; however, it needs some mechanical stability. The focus of this paper is the development of a SAlg/PVA nanofibrous material with improved mechanical properties using a crosslinking agent 1-ethyl-3-(-3-dimethylaminopropyl) carbodiimide hydrochloride/N-Hydroxysuccinimide (EDC/NHS) by electrospinning. The obtained electrospun nanofibrous nonwoven was characterized by using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), water contact angle, and tensile test. The results have shown that the mechanical properties of the electrospun SAlg/PVA nanofibrous nonwoven were significantly enhanced with the addition of EDC/NHS. Moreover, the electrospun SAlg/PVA-EDC/NHS nanofibrous nonwoven was found relatively stable against the water than the electrospun SAlg/PVA nanofibrous nonwoven. This preliminary report shows that the advanced alginate-based nanofibrous nonwoven is a promising candidate for many application fields such as textile, food, and biomedical.

Studying the Physical Properties of Non-Woven Polyacrylonitrile Nanofibers after Adding γ-Fe2O3 Nanoparticles .

This research focuses on preparing and studying the behavior of non-woven polyacrylonitrile (PAN) nanofibers after adding γ- Fe2O3 nanoparticles to (PAN / N, N dimethylformamide (DMF)) solution with (1.45, 4.3, and 7.14) wt. %. In order to achieve the morphology properties, textural directionality, the bonding between iron oxide particles and the PAN matrix, thermal, crystalline, and magnetic properties we did the Field-Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Near-Infrared Spectroscopy (FT-NIR), Differential Calorimeter Scanning (DSC), X-Ray Diffraction (XRD), and Vibration Sample Magnetometer (VSM). Laboratory analyses demonstrated the significant influence of iron oxide nanoparticles on the characteristics and performance of the composite nanofibers in terms of reduced nanofiber diameter from 109.38±29.70 to 78.17±36.898 nm, the disappearance of beads. In addition to an increase in the crystallinity from 82.43 to 94.28 % accompanied by a larger crystalline size as a result of the polymeric fibers acquiring high magnetic properties after strengthening them with iron oxide nanoparticles, the saturation magnetization (Ms) increases with the increase of iron oxide loading in the nanofibers from (1.426 emu/g) at 1.45 wt.% γ- Fe2O3 to (6.85 emu/g) to 7.14 wt.% γ- Fe2O3 .

An investigation into the designing of fibrous sound absorption materials incorporated with nanofibers: a case study of a multi-layered material composed of PET nonwoven and PAN nanofibers

The present work aimed to investigate the effect of nanofiber enhancement on the sound absorption performance of fibrous materials through a brief review of the recent progress in the field and highlight the current challenges and issues for measuring and modeling the sound absorption coefficient (SAC) of such structures. Moreover, some composite samples consist of polyethylenterephthalat (PET) nonwoven fabric and polyacrylonitrile (PAN) nanofibers web were prepared to be studied as a case study. The nanofiber deposition amounts, nanofiber orientation, and nanofiber layering sequence were chosen as the main variables of samples. Various amounts of deposition were achieved through three different electrospinning (ES) time of 15, 60, and 180 min. The random and aligned orientation of the nanofiber web was obtained by using a rotating collector. The effect of the layering sequence of the nanofiber layer was studied in the form of quadruple-layered assemblies of samples. The results showed that the samples incorporated with the nanofiber layer with 60 min of ES and random orientation when it is used in the second position of the layering sequence have the best performance of sound absorption, mainly at lower critical frequency range. Furthermore, a discussion on some available empirical models and compare the results confirms that there is a need for developing a new approach for measuring and modeling the SAC and consequently designing such absorbers.

How Nanofibers Carry the Load: Toward a Universal and Reliable Approach for Tensile Testing of Polymeric Nanofibrous Membranes

Back Cover: Mechanical properties assessment of nanofibrous nonwovens is complex due to their porous morphology and soft nature, possibly leading to inaccurate results. In article number 2100183 by Laura Mazzocchetti, Andrea Zucchelli, and co-workers, the high reliability of mass-based normalization of load with respect to the cross-section is proposed and demonstrated using Nylon 66 nanofibers, providing a simple, effective, and universally suitable method for obtaining highly reproducible tensile stress–strain curves.

Novel Poly(ester urethane urea)/Polydioxanone Blends: Electrospun Fibrous Meshes and Films.

In this work, we report the electrospinning and mechano-morphological characterizations of scaffolds based on blends of a novel poly(ester urethane urea) (PHH) and poly(dioxanone) (PDO). At the optimized electrospinning conditions, PHH, PDO and blend PHH/PDO in Hexafluroisopropanol (HFIP) solution yielded bead-free non-woven random nanofibers with high porosity and diameter in the range of hundreds of nanometers. The structural, morphological, and biomechanical properties were investigated using Differential Scanning Calorimetry, Scanning Electron Microscopy, Atomic Force Microscopy, and tensile tests. The blended scaffold showed an elastic modulus (~5 MPa) with a combination of the ultimate tensile strength (2 ± 0.5 MPa), and maximum elongation (150% ± 44%) in hydrated conditions, which are comparable to the materials currently being used for soft tissue applications such as skin, native arteries, and cardiac muscles applications. This demonstrates the feasibility of an electrospun PHH/PDO blend for cardiac patches or vascular graft applications that mimic the nanoscale structure and mechanical properties of native tissue.

Carbon dioxide capture using nonwoven activated carbon nanofiber

The adsorption isotherms and kinetic uptakes of Carbon Dioxide (CO2) on fabricated electrospun nonwoven activated carbon nanofiber sheets were investigated at two different temperatures, 308 K and 343 K, over a pressure range of 1 to 7 bar. The activated carbon nanofiber-based on polymer (PAN) precursor was fabricated via electrospinning technique followed by thermal treatment to obtain the carboneous nanofibers. The obtained data of CO2 adsorption isotherm was fitted to various models, including Langmuir, Freundlich, and Temkin. Based on correlation coefficients, the Langmuir isotherm model presented the best fitting with CO2 adsorption isotherms’ experimental data. Raising the equilibrium adsorption temperature decreased the total amount adsorbed, indicating an exothermic adsorption process of CO2 on CNF and ACNF. It was also observed from the adsorption kinetic data that increasing the flow rate decreased the breakthrough point and the saturation time in the adsorption column. The efficiency of CO2 adsorption on ACNF (82 %) was better than that on nonwoven carbon nanofiber (CNF) (67 %) due to the high specific surface area and pore volume of ACNF (375 m2/g, 0.051 m3/g) comparing to CNF (20 m2/g, 0.0167 m3/g).