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"Electrospinning"
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Piezoelectric Properties of Electrospun Polymer Nanofibers and Related Energy Harvesting Applications
Electrospinning (ES) methods that can produce piezoelectricity in polymer nanofibers have attracted tremendous research attention. These electrospun polymer nanofibers can be employed for sensors, energy harvesting, tissue engineering, and filtration applications. This paper reviews the performance of a variety of electrospun piezoelectric polymer nanofibers produced by different ES methods, including near‐field electrospinning and conventional far‐field electrospinning methods. Herein, it is described how the ES method can affect the piezoelectric properties of various polymer nanofibers, including poly(vinylidene difluorine), poly(vinylidene fluoride‐trifluoroethylene), nylon 11, poly(l‐lactic acid), and poly(α‐benzyl‐l‐glutamate). Due to the varied matrix structures of piezoelectric polymer nanofibers, the ES method may conduct variable effects on the piezoelectric properties of polymer nanofibers. After characterizations by X‐ray diffraction, Fourier transform infrared spectrum, dielectric spectra, and piezoelectric coefficient measurements, it is found that the piezoelectric properties of the polymer nanofibers can be significantly affected by the ES parameters. Most of previous review articles focus on the output performance of electrospun polymer nanofibers. A detailed description of how different ES methods affect the piezoelectricity of polymer nanofibers is still lacking. In this review paper, the basic principle behind ES methods and the way in which different ES methods affect the properties of polymer nanofibers are examined. This paper reviews the piezoelectric properties of electrospun polymer nanofibers produced by different electrospinning (ES) methods, including near‐field electrospinning and conventional far‐field electrospinning methods. The polymers include poly(vinylidene difluorine), nylon 11, poly(l‐lactic acid), and poly(α‐benzyl‐l‐glutamate). The aim of the review is to find the basic principle behind ES methods and how different ES methods affect the properties of polymer nanofibers.
Journal Article
Controlled synthesis and tunable photoluminescence properties of LaOBr:Eu super(3+) nanostructures
Eu super(3+) doped lanthanum oxybromide (LaOBr) nanostructures including nanofibers, nanoribbons, and hollow nanofibers were fabricated for the first time via calcining the electrospun PVP/[La(NO sub(3)) sub(3)+Eu(NO sub(3)) sub(3)+NH sub(4)Br] composites. X-ray diffraction analysis results showed that LaOBr:Eu super(3+) nanostructures were tetragonal in structure with space group of P4/nmm. The morphologies and sizes of the LaOBr:Eu super(3+) nanostructures were studied by scanning electron microscope and transmission electron microscope. The mean diameter of the nanofibers and hollow nanofibers, and the width of nanoribbons are 118.02 plus or minus 14.21, 115.84 plus or minus 13.37 nm, and 1.56 plus or minus 0.25 mu m, respectively. Under the excitation of 289 nm ultraviolet light, LaOBr:Eu super(3+) nanostructures exhibit the red emissions of predominant peak at 618 nm, which is ascribed to the super(5)D sub(0) arrow right super(7)F sub(2) transition of the Eu super(3+) ions. It is found that the optimum doping concentration of the Eu super(3+) ions in the LaOBr:Eu super(3+) nanofibers is 5 %. Interestingly, we found that the luminescence intensity of nanofibers is obviously greater than that of the hollow nanofibers and nanoribbons for LaOBr:Eu super(3+) under the same measuring conditions. Moreover, the color emissions of LaOBr:Eu super(3+) nanostructures can be tuned by adjusting the concentration of Eu super(3+) and the morphologies of nanomaterials. The obtained LaOBr:Eu super(3+) nanostructures may be promising nanomaterials for applications in the fields of light display systems and optoelectronic devices.
Journal Article
Recent Progress in Preparing Nonwoven Nanofibers via Needleless Electrospinning
Electrospinning has received a lot of attention in recent years because it can create nonwoven nanofiber webs with high surface area and porosity. However, the typical needle and syringe‐based electrospinning systems feature poor productivity that has limited their usefulness in the industrial field. Here, current developments in the creation of nanofibers employing nonconventional electrospinning methods, such as needleless electrospinning and syringeless electrospinning, are examined. These alternate electrospinning techniques, which are dependent on numerous polymer droplets of varied shapes, have the potential to match the productivity required for industry‐scale manufacturing of nanofibers. Additionally, they make it possible to produce nanofibers that are difficult to spin using traditional techniques, like electrospinning of colloidal suspensions.
Journal Article
Electrospinning of Potential Medical Devices (Wound Dressings, Tissue Engineering Scaffolds, Face Masks) and Their Regulatory Approach
Electrospinning is the simplest and most widely used technology for producing ultra-thin fibers. During electrospinning, the high voltage causes a thin jet to be launched from the liquid polymer and then deposited onto the grounded collector. Depending on the type of the fluid, solution and melt electrospinning are distinguished. The morphology and physicochemical properties of the produced fibers depend on many factors, which can be categorized into three groups: process parameters, material properties, and ambient parameters. In the biomedical field, electrospun nanofibers have a wide variety of applications ranging from medication delivery systems to tissue engineering scaffolds and soft electronics. Many of these showed promising results for potential use as medical devices in the future. Medical devices are used to cure, prevent, or diagnose diseases without the presence of any active pharmaceutical ingredients. The regulation of conventional medical devices is strict and carefully controlled; however, it is not yet properly defined in the case of nanotechnology-made devices. This review is divided into two parts. The first part provides an overview on electrospinning through several examples, while the second part focuses on developments in the field of electrospun medical devices. Additionally, the relevant regulatory framework is summarized at the end of this paper.
Journal Article
Coaxial Electrospinning Formation of Complex Polymer Fibers and their Applications
The formation of fibers by electrospinning has experienced explosive growth in the past decade, recently reaching 4,000 publications and 1,500 patents per year. This impressive growth of interest is due to the ability to form fibers with a variety of materials, which lend themselves to a large and rapidly expanding set of applications. In particular, coaxial electrospinning, which forms fibers with multiple core−sheath layers from different materials in a single step, enables the combination of properties in a single fiber that are not found in nature in a single material. This article is a detailed review of coaxial electrospinning: basic mechanisms, early history and current status, and an in‐depth discussion of various applications (biomedical, environmental, sensors, energy, catalysis, textiles). We aim to provide readers who are currently involved in certain aspects of coaxial electrospinning research an appreciation of other applications and of current results. Mix and match: In this Review, the basic operation of conventional electrospinning for the formation of homogenous fibers is briefly discussed and then coaxial electrospinning and process parameters for the formation of complex core‐sheath fibers are described. Early breakthroughs in coaxial electrospinning are introduced and then recent results are reviewed in some detail regarding the formation and properties of coaxial fibers for several key application areas: biomedical, sensors, textiles, energy, and catalysis.
Journal Article
Near-Field Direct Write Electrospinning of PET-Carbon Quantum Dot Solutions
Electrospinning of polymer material has gained a lot of interest in the past decades. Various methods of electrospinning have been applied for different applications, from needle electrospinning to needleless electrospinning. A relatively new variation of electrospinning, namely near-field electrospinning, has been used to generate well-defined patterns. This variation of electrospinning, also known as near-field direct-write electrospinning, allows for precise control of the fiber deposition, sacrificing on the thickness of the resulting fibers. Typically, for this method, melt electrospinning is preferred, since it provides a higher viscosity of the polymer and thereby better control of the fiber deposition. However, when mixing additives into the spinning dope, a solution spinning approach is preferable since it provides a more homogeneous distribution of the additives in the spinning dope. A fluorescent spinning dope of dissolved PET with fluorescent carbon quantum dots has been used to generate the fluorescent patterns. These can be used to generate logos, bar codes, or QR codes to encode information about the material, such as watermarks or counterfeiting tags.
Journal Article
A Mini-Review: Needleless Electrospinning of Nanofibers for Pharmaceutical and Biomedical Applications
Electrospinning (ES) is a convenient and versatile method for the fabrication of nanofibers and has been utilized in many fields including pharmaceutical and biomedical applications. Conventional ES uses a needle spinneret for the generation of nanofibers and is associated with many limitations and drawbacks (i.e., needle clogging, limited production capacity, and low yield). Needleless electrospinning (NLES) has been proposed to overcome these problems. Within the last two decades (2004–2020), many research articles have been published reporting the use of NLES for the fabrication of polymeric nanofibers intended for drug delivery and biomedical tissue engineering applications. The objective of the present mini-review article is to elucidate the potential of NLES for designing such novel nanofibrous drug delivery systems and tissue engineering constructs. This paper also gives an overview of the key NLES approaches, including the most recently introduced NLES method: ultrasound-enhanced electrospinning (USES). The technologies underlying NLES systems and an evaluation of electrospun nanofibers are presented. Even though NLES is a promising approach for the industrial production of nanofibers, it is a multivariate process, and more research work is needed to elucidate its full potential and limitations.
Journal Article
Dynamic mechanical analysis and morphological characterization of electrospun polycaprolactone, gelatin and PCL/Gelatin (50/50) scaffolds
This research concerns the production of three electrospun scaffolds: the first produced from a synthetic polymer, polycaprolactone (PCL); the second from a natural polymer, porcine gelatin type A, crosslinked with glutaraldehyde vapors (G); and the third from a mixture of both in a 50/50 (m/m) PCL/G composition. The objective of this paper is to define the operating parameters for electrospinning the substances and to perform a mechanical evaluation of the resulting scaffolds using Dynamic Mechanical Analysis (DMA). Initially, defective scaffolds with lumpy fibers were obtained, but adjusting the variables resulted in scaffolds with a smooth, porous fibrous morphology. DMA was applied to the three scaffolds, and the storage modulus (E’), loss modulus (E’’), and damping factor (tan δ) were determined for each to estimate the state transition temperature. The main results yielded matrices with suitable morphologies and viscoelastic behavior, making them promising candidates for use in tissue regeneration.
Journal Article
Melt Electrospinning Designs for Nanofiber Fabrication for Different Applications
Nanofibers have been attracting growing attention owing to their outstanding physicochemical and structural properties as well as diverse and intriguing applications. Electrospinning has been known as a simple, flexible, and multipurpose technique for the fabrication of submicro scale fibers. Throughout the last two decades, numerous investigations have focused on the employment of electrospinning techniques to improve the characteristics of fabricated fibers. This review highlights the state of the art of melt electrospinning and clarifies the major categories based on multitemperature control, gas assist, laser melt, coaxial, and needleless designs. In addition, we represent the effect of melt electrospinning process parameters on the properties of produced fibers. Finally, this review summarizes the challenges and obstacles connected to the melt electrospinning technique.
Journal Article