Morphologies and Properties of PET Nano Porous Luminescence Fiber: Oil Absorption and Fluorescence-Indicating Functions

Application of the Electrospinning Technique in Electrochemical Biosensors: An Overview

Electrospinning is a cost-effective and flexible technology for producing nanofibers with large specific surface areas, functionalized surfaces, and stable structures. In recent years, electrospun nanofibers have attracted more and more attention in electrochemical biosensors due to their excellent morphological and structural properties. This review outlines the principle of electrospinning technology. The strategies of producing nanofibers with different diameters, morphologies, and structures are discussed to understand the regulation rules of nanofiber morphology and structure. The application of electrospun nanofibers in electrochemical biosensors is reviewed in detail. In addition, we look towards the future prospects of electrospinning technology and the challenge of scale production.

C-shaped porous polypropylene fibers for rapid oil absorption and effective on-line oil spillage monitoring

Development of efficient absorbent materials for detection and treatment of offshore oil spillages remained a challenge. In this work, C-shaped polypropylene oil-absorbent fibers with sub-micron internal pores were prepared by combining spun-bonding technique and thermally induced phase separation (TIPS). The effect of drawing speed on the phase separation and the porous morphology of the shaped fiber non-woven fabric (NWF) was investigated. C-shaped NWF with porous morphology had large water contact angle, higher porosity, larger specific surface area, and increased oil absorption speed and capacity. An online oil spillage detection system was developed using porous C-shaped NWF and an oxygen sensing probe, showing shorter response time and higher signal-to-noise (STN) ratio. The response time for detecting the spillage of soybean oil and diluted crude oil (0.5 mL/0.8 L) in water were only 24 s and 10 s, respectively. The reliable oil detection low detection limit (RLDL) of the oxygen sensing probe was reduced 173 times (from 36.5 g/L to 0.21 g/L) when combined with C-shaped porous fiber NWF.

Preparation of Thermosensitive Fluorescent Polyacrylamide Nanofiber Membrane and Visual Temperature Sensing

Fluorescent fibers are capable of discoloration behavior under special light sources, showing great potential for applications in biomedicine, environmental monitoring, heavy-metal-ion detaction, and anti-counterfeiting. In the current paper, temperature-sensitive fluorescent poly-acrylamide (PAM) nanofiber (AuNCs@PAM NF) membranes are prepared by mixing red fluorescent gold nanoclusters (AuNCs) synthesized in-house with PAM using the electrospinning technique. The AuNCs@PAM nanofibers obtained using this method present excellent morphology, and the AuNCs are uniformly dispersed in the fibers. The average diameter of the AuNCs@PAM NFs is 298 nm, and the diameter of AuNCs doped in the fibers is approximately 2.1 nm. Furthermore, the AuNCs@PAM NF films present excellent fluorescence and temperature-sensitive performance between 15 and 65 degrees. While under the 365 nm UV light source, the fiber film changes from white to red; this discoloration behavior weakens with the increase in temperature, and changes from deep to light red. Therefore, the approximate temperature can be identified using the color change, and a visual temperature-sensing effect can be achieved. The dual functions of temperature-sensitivity and fluorescent properties improve the scientificity and safety of nanofibers in the use of anti-counterfeiting technology.

Magnetic γ-Fe2O3/ZIF-7 Composite Particles and Their Application for Oily Water Treatment

Crude oil spills are about global challenges because of their destructive effects on aquatic life and the environment. The conventional technologies for cleaning crude oil spills need to study the selective separation of pollutants. The combination of magnetic materials and porous structures has been of considerable interest in separation studies. Here, γ-Fe₂O₃/ZIF-7 structures were prepared by growing a ZIF-7 layer onto supermagnetic γ-Fe₂O₃ nanoparticles with an average size of 18 ± 0.9 nm in situ without surface modification at low temperatures. The product composite particles were characterized using X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy, vibrating sample magnetometry, and N₂ adsorption/desorption isotherms. The analyses revealed a time growth-dependent ZIF-7 rod thickness with abundant nanocavities. The γ-Fe₂O₃/ZIF-7 surface area available for sorption (647 m²/g) is ∼12-fold higher than that of the γ-Fe₂O₃ nanoparticles. Moreover, the crystal structure of γ-Fe₂O₃ remained essentially unchanged following ZIF-7 coating, whereas the superparamagnetism declined depending on the coating time. The γ-Fe₂O₃/ZIF-7 particles were highly hydrophobic and selectively and rapidly (<5 min) sorbed crude oil and other hydrocarbon pollutants from water. As high as 6 g/g of the hydrocarbon was sorbed by the γ-Fe₂O₃/ZIF-7 particles immersed into the hydrocarbon. A coefficient of determination, R ₂ ², consistently >0.96 at all pollutant concentrations suggested a pseudo-second-order sorption kinetics. The thermal stability and 15 cycles of use and reuse confirmed a robust γ-Fe₂O₃/ZIF-7 sorbent.

Hierarchical Porous Recycled PET Nanofibers for High-Efficiency Aerosols and Virus Capturing

Plastic crisis, especially for poly(ethylene terephthalate) (PET) bottles, has been one of the greatest challenges for the earth and human beings. Processing recycled PET (rPET) into functional materials has the dual significance of both sustainable development and economy. Providing more possibilities for the engineered application of rPET, porous PET fibers can further enhance the high specific surface area of electrospun membranes. Here, we use a two-step strategy of electrospinning and postprocessing to successfully control the surface morphology of rPET fibers. Through a series of optical and thermal characterizations, the porous morphology formation mechanism and crystallinity induced by solvents of rPET fibers were discussed. Then, this work further investigated both PM2.5 air pollutants and protein filtration performance of rPET fibrous membrane. The high capture capability of rPET membrane demonstrated its potential application as an integrated high-efficiency aerosol filtering solution.

Electrospun Wrinkled Porous Polyimide Nanofiber-Based Filter via Thermally Induced Phase Separation for Efficient High-Temperature PMs Capture

Benefiting from its superior thermal stability, polyimide (PI) fiber-based composites have attracted wide attention in the field of high-temperature filtration and separation. However, the trade-off between filtration efficiency and pressure drop of traditional PI filters with single morphology and structure still remains challenging. Herein, the electrospun PI high-temperature-resistant air filter was fabricated via thermal-induced phase separation (TIPS), employing polyacrylonitrile (PAN) as a template. The PI nanofibers exhibited special wrinkled porous structure, and the filter possessed a high specific surface area of 304.77 m²/g. The removal of PAN changed the chemical composition of the fiber and induced PI molecules to form complex folds on the surface of the fiber, thus forming the wrinkled porous structure. Additionally, the wrinkled porous PI nanofiber filter displayed a high PM0.3 removal efficiency of 99.99% with a low pressure drop of 43.35 Pa at room temperature, and the filtration efficiency was still over 97% after being used for long time. Moreover, the efficiency of the filter could even reach 95.55% at a high temperature of 280 °C. The excellent filtration performance was attributed to the special wrinkled porous surface, which could limit the Brownian motion of PMs and reinforce the mechanical interception effect to capture the particulate matters (PMs) on the surface of the filter. Therefore, this work provided a novel strategy for the fabrication of filters with special morphology to cope with increasingly serious air pollution in the industrial field.

One-step electrospinning cellulose nanofibers with superhydrophilicity and superoleophobicity underwater for high-efficiency oil-water separation

Cellulose nanofibers have been widely applied in many fields because of its unique advantages. However, it is a challenge to prepare cellulose nanofibers by electrospinning directly owing to the special molecular structure of cellulose. This limits the practical applications of cellulose nanofibers. In this work, cellulose nanofibers were successfully prepared directly by design of new electrospinning receiving device and optimization of process parameters. The as-prepared cellulose nanofibers exhibit good oil-water separation performances. Driven solely by gravity, the separation flux of the cellulose nanofibers for mixture of oil and water reaches 34,300.6 L m^-2 h^-1, and the separation flux and efficiency for surfactant-stabilized emulsion of oil and water reach 2503.7 L m^-2 h^-1 and over 98.3%, respectively. The as-prepared cellulose nanofibers also exhibit good mechanical properties and reusability. The breaking strength of the cellulose nanofibers can reach 148.2 cN. The separation fluxes of cellulose nanofibers for mixtures and emulsions of oil and water can be maintained 99.7% and 86.3% of the initial value after being used for 20 times. Furthermore, the as-prepared cellulose nanofibers have good degradability. These properties render as-prepared cellulose nanofibers as promising materials with potential applications in oil-water separation.

Electrospinning and Electrospun Nanofibers: Methods, Materials, and Applications

Electrospinning is a versatile and viable technique for generating ultrathin fibers. Remarkable progress has been made with regard to the development of electrospinning methods and engineering of electrospun nanofibers to suit or enable various applications. We aim to provide a comprehensive overview of electrospinning, including the principle, methods, materials, and applications. We begin with a brief introduction to the early history of electrospinning, followed by discussion of its principle and typical apparatus. We then discuss its renaissance over the past two decades as a powerful technology for the production of nanofibers with diversified compositions, structures, and properties. Afterward, we discuss the applications of electrospun nanofibers, including their use as "smart" mats, filtration membranes, catalytic supports, energy harvesting/conversion/storage components, and photonic and electronic devices, as well as biomedical scaffolds. We highlight the most relevant and recent advances related to the applications of electrospun nanofibers by focusing on the most representative examples. We also offer perspectives on the challenges, opportunities, and new directions for future development. At the end, we discuss approaches to the scale-up production of electrospun nanofibers and briefly discuss various types of commercial products based on electrospun nanofibers that have found widespread use in our everyday life.

Integrating Nano-Cu₂O@ZrP into In Situ Polymerized Polyethylene Terephthalate (PET) Fibers with Enhanced Mechanical Properties and Antibacterial Activities

The approach of in situ polymerization modification has proven to be an effective route for introducing functions for polyester materials. In this work, Cu₂O@ZrP nanosheets with excellent dispersity and high antibacterial activity were integrated into in situ polymerized polyethylene terephthalate (PET) fibers, revealing an enhanced mechanical performance in comparison with the PET fibers fabricated directly via a traditional melt blending method. Additionally, such an in situ polymerized PET/Cu₂O@ZrP fibers displayed highly enhanced mechanical properties; and great antibacterial activities against multi-types of bacterium, including S. aureus, E. coli and C. albicans. For the as-obtained two types of PET/Cu₂O@ZrP fibers, we have detailed their molecular weight (detailed molecular weight) and dispersibility of nano-Cu₂O@ZrP and fibers crystallinity was investigated by Gel chromatography (GPC), Scanning electron microscope (SEM), and X-ray diffractometer (XRD), respectively. The results showed that the aggregation of the nano-Cu₂O@ZrP in the resultant PET matrix could be effectively prevented during its in situ polymerization process, hence we attribute its highly enhanced mechanical properties to its superior dispersion of nano-Cu₂O@ZrP.