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Abstract: Eco-friendly tree-like porous carboxyl modified cellulose nanofiber membranes as highly efficient adsorbents for heavy metal ions were fabricated by the electrospinning of cellulose acetate (CA)/tetrabutylammonium chloride (TBAC)/manganese dioxide (MnO2) solution, and subsequent deacetylation treatment to turn CA into cellulose and citric acid modification to graft carboxyl group on the surface of cellulose nanofibers. The addition of TBAC led to the formation of tree-like structure and MnO2 particles were used as pore-forming agents. The effects of pH, initial ion concentrations and contact time on the removal capacity of heavy metal ions were investigated. During the removal process, the abundant carboxyl groups (-COOH) transferred to carboxylate ions (-COO−) which had stronger ion exchange ability to the metal ion adsorption. In addition, the tree-like porous structure supplied large specific surface area and effectively increased the removal capacity. The removal process could reach a plateau in 90 min with the maximum removal amount of 399.14 mg/g. The removal process was also depicted by Langmuir and Freundlich isotherm model. Generally, the tree-like porous structure will have extensive prospects in the fields of filtration, electrochemistry, tissue engineering and so on.Graphical abstract: [ABSTRACT FROM AUTHOR]

Herein, the composite carbon material of porous carbon nanofiber and carbon nanotube is developed via electro-blown spinning and one-step simultaneous carbonization and chemical vapor deposition without injecting every kind of reaction gas in proportion and removing catalyst in secondary processing. The carbon nanotubes are uniformly growing on carbon skeleton which dramatically improve the performances such as specific surface area (from 334.066 to 644.589 m2 g−1) and electrical conductivity (from 42.22 to 146.20 S cm−1) comparing with porous carbon nanofibers. The different spinning parameters are investigated to optimize parameters, and the porous carbon nanofiber and carbon nanotube are studied and used as electrode for supercapacitors. The results showed that it possesses excellent electrochemical properties, including high specific discharge capacity (216.5 F g−1 at 1.0 A g−1) and good cycle performance (retains ~ 98.68% after 5000 cycles). Moreover, the convenient one-step prepared method special throughout pores structure and superior performance provide a novel approach for designing new types of carbon composite materials which also possess potential application prospect in fields of catalyst, adsorption, etc. [ABSTRACT FROM AUTHOR]

A hierarchically Ag/nylon 6 tree-like nanofiber membrane (Ag/PA6 TLNM) was fabricated by adding tetrabutylammonium chloride (TBAC) and silver nitrate (AgNO3) into spinning solution via one-step electrospinning. TBAC presented in PA6/formic acid (HCOOH) spinning solution was able to cause the formation of a tree-like structure due to its space steric structure and the increasing of solution conductivity. Electrospinning solvent acted as a reducing agent for in situ conversion of AgNO into silver nanoparticles (Ag NPs) during the solution preparation. SEM, TEM, FT-IR XPS and XRD confirmed that Ag NPs were doped in the prepared nanofiber membrane successfully and the mechanical properties, pore size distribution and hydrophilicity of the membranes were investigated. The results showed that the tree-like structure improved the mechanical properties and hydrophilicity of the membrane while ensuring high specific surface area and small pore size. And the Ag/PA6 TLNM showed superior antibacterial properties against both E. coli and S. aureus compared with common Ag/PA6 nanofiber membranes (Ag/PA6 NMs). All of the results show that the Ag/PA6 TLNM would have potential applications in water purification. [ABSTRACT FROM AUTHOR]

The membranes for gel polymer electrolyte (GPE) for lithium-ion batteries were prepared by electrospinning a blend of poly(vinylidene fluoride) (PVdF) with cellulose acetate (CA). The performances of the prepared membranes and the resulted GPEs were investigated, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), X-ray diffraction (XRD), porosity, hydrophilicity, electrolyte uptake, mechanical property, thermal stability, AC impedance measurements, linear sweep voltammetry, and charge-discharge cycle tests. The effect of the ratio of CA to PVdF on the performance of the prepared membranes was considered. It is found that the GPE based on the blended polymer with CA:PVdF =2:8 (in weight) has an outstanding combination property-strength (11.1 MPa), electrolyte uptake (768.2 %), thermal stability (no shrinkage under 80 °C without tension), and ionic conductivity (2.61 × 10 S cm). The Li/GPE/LiCoO battery using this GPE exhibits superior cyclic stability and storage performance at room temperature. Its specific capacity reaches up to 204.15 mAh g, with embedded lithium capacity utilization rate of 74.94 %, which is higher than the other lithium-ion batteries with the same cathode material LiCoO (about 50 %). [ABSTRACT FROM AUTHOR]

As a kind of high-performance fibers, PTFE fiber has been widely used in many fields because of its unique characteristics. In this study, the poly(tetrafloroethylene) (PTFE) nanofibers manufactured by electrospinning method was reported. The gel-spinning solution of poly(tetrafluoroethylene)/poly(vinyl alcohol)/boric acid (PTFE/PVA/BA), which was prepared by the gel process of the mixture of PTFE, PVA, BA and redistilled water, was electrospun to form PTFE/PVA/BA composite nanofibers. After calcinating, the PTFE nanofibers with diameters of 200 nm to 1000 nm were obtained. The fibers before and after calcinating were characterized by scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), FT-IR spectrum analysis and X-ray photoelectron spectroscopy (XPS), respectively, and the mechanical and hydrophobic properties of the fibers were also investigated. The results showed that the PTFE nanofiber membranes could be electrospun effectively used the gel-spinning solution of PTFE/PVA/BA, and may realize the applications in the fields of high-temperature filtration, catalyst supports, battery separator and so on. [ABSTRACT FROM AUTHOR]