Electrospun poly(L-lactide)-grafted hydroxyapatite/poly(L-lactide) nanocomposite fibers

Composite fibers composed of poly(L-lactide)-grafted hydroxyapatite (PLA-g-HAP) nanoparticles and polylactide (PLA) matrix were prepared by electro-spinning. Environmental scanning electron microscope (ESEM) and transmission electron microscopy (TEM) were employed to investigate the morphology of the composite fibers and the distribution of PLA-g-HAP nanoparticles in the fibers, respectively. At a low content (similar to 4 wt%) of PLA-g-HAP, the nanoparticles dispersed uniformly in the fibers and the composite fibrous mats exhibited higher strength properties, compared with the pristine PLA fiber mats and the simple hydroxyapatite/PLA blend fiber mats. But when the content of PLA-g-HAP further increased, the nanoparticles began to aggregate, which resulted in the deterioration of the mechanical properties of the composite fiber mats. The degradation behaviors of the composite fiber mats were closely related to the content of PLA-g-HAP. At a low PLA-g-HAP content, degradation may be delayed due to the reduction of autocatalytic degradation of PLA. When PLA-g-HAP content was high, degradation rate increased because of the enhanced wettability of the composite fibers and the escape of the nanoparticles from fiber surfaces during incubation.

Upconversion Luminescence of Er3+-Yb3+ Codoped NaYF4-PVP Electrospun Nanofibers

NaYF4: 0.02Er center dot xYb-PVP composite nanofibers with the diameter of similar to 400 nm have been prepared by electrospinning. Field emission scanning electron microscope and X-ray diffraction have been utilized to characterize morphology and structure of the as-prepared electrospun nanofibers. Their up-conversion luminescence is investigated under a 980-nm excitation. Green (538 and 520 nm), red (6-55 nm), and blue (405 nm) emissions are observed in the up-conversion luminescence spectra, and the intensity of these three emissions changes differently with the variety of Yb content, which has been interpreted successfully in this letter. The color of NaYF4: 0.02Er center dot xYb-PVP nanolibers under a 980-nm excitation can be changed from green --> white --> yellow gradually via changing the Yb content.

Hollow fibers of yttria-stabilized zirconia (8YSZ) prepared by calcination of electrospun composite fibers

8YSZ fibers were synthesized by calcination of PVP/zirconium oxychloride/yttrium nitrate composite fibers (PVP-Precursor) obtained by electrospinning. Scanning electron microscopy (SEM) indicated that the 8YSZ fibers are hollow and the gas released during organic binder decomposition resulted in the formation of hollow center in fibers

Electrospun palladium nanoparticle-loaded carbon nanofibers and their electrocatalytic activities towards hydrogen peroxide and NADH

Palladium nanoparticle-loaded carbon nanofibers (Pd/CNFs) were synthesized by the combination of electrospinning and thermal treatment processes. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show that spherical Pd nanoparticles (NPs) are well-dispersed on the surfaces of CNFs or embedded in CNFs. X-ray diffraction (XRD) pattern indicates that cubic phase of Pd was formed during the reduction and carbonization processes, and the presence of Pd NPs promoted the graphitization of CNFs. This nanocomposite material exhibited high electric conductivity and accelerated the electron transfer, as verified by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV).

Simultaneous determination of dopamine, ascorbic acid and uric acid with electrospun carbon nanofibers modified electrode

A novel carbon-nanofiber-modified carbon-paste electrode (CNF-CPE) was employed for the simultaneous determination of dopamine (DA), ascorbic acid (AA) and uric acid (UA) with good selectivity and high sensitivity. The CNFs were prepared by combination of electrospinning technique with thermal treatment method and were used without any pretreatment. In application to determination of DA, AA and UA in the ternary mixture, the pristine CNF-CPE exhibited well-separated differential pulse voltammetric peaks with high catalytic current. Low detection limits of 0.04 mu M, 2 mu M and 0.2 mu M for DA, AA and UA were obtained, with the linear calibration curves over the concentration range 0.04-5.6 mu M, 2-64 mu M and 0.8-16.8 mu M, respectively.

Well-defined higher-molecular-weight polyacrylonitrile via RAFT technique in the presence of disulfide compounds as a source of chain transfer agent

Well-defined polyacrylonitrile with a higher number-average molecular weight (R.) up to 200,000 and a lower polydispersity index (PDI, 1.7-2.0) was firstly obtained via reversible addition-fragmentation chain transfer (RAFT) process. This was achieved by selecting a stable, easy way to prepare disulfide compound intermediates including bis(thiobenzoyl) disulfide (BTBDS) and bis(thiophenylacetoyl) disulfide (BTPADS) to react with azobis(isobutyronitrile) to directly synthesize RAFT agents in situ.

Preparation of Hollow Carbon and Silicon Carbide Fibers with Different Cross-Sections by using Electrospun Fibers as Templates

Hollow carbon nanofibers with circular and rectangular opening were prepared by using electrospun silica fibers as templates. Silica fibers were synthesized by electrospinning, and they were coated with a carbon layer formed by thermal decomposition and carbonization of polystyrene under a nitrogen atmosphere. Hollow carbon nanofibers with circular and rectangular openings were then obtained after the silica core was etched by hydrofluoric acid. The carbon nanofibers with different morphologies also could be used as templates to fabricate silicon carbide fibers. The silicon carbide fibers with circular and rectangular openings could be obtained by using hollow carbon nanofibers and carbon belts as templates, respectively.

Highly efficient electrocatalytic oxidation of formic acid by electrospun carbon nanofiber-supported PtxAu100-x bimetallic electrocatalyst

Electrospun carbon nanofiber-supported bimetallic PtxAu100-x electrocatalysts (PtxAu100-x/CNF) were prepared by electrochemical codeposition method. The composition of PtAu bimetallic nanoparticles could be controlled by varying the ratio of H2PtCl6 and HAuCl4. Scanning electron microscopy images showed that bimetallic nanoparticles had coarse surface morphology with high electrochemically active surface areas. X-ray diffraction analysis testified the formation of PtAu alloys. PtxAu100-x/CNF electrocatalysts exhibited improved electrocatalytic activities towards formic acid oxidation by providing the selectivity of the reaction via dehydrogenation pathway and suppressing the formation/adsorption of poisoning CO intermediate, indicating that PtxAu100-x/CNF is promising electrocatalyst in direct formic acid fuel cells.

Nonenzymatic glucose sensor based on renewable electrospun Ni nanoparticle-loaded carbon nanofiber paste electrode

A novel nonenzymatic glucose sensor was developed based on the renewable Ni nanoparticle-loaded carbon nanofiber paste (NiCFP) electrode. The NiCF nanocomposite was prepared by combination of electrospinning technique with thermal treatment method. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that large amounts of spherical nanoparticles were well dispersed on the surface or embedded in the carbon nanofibers. And the nanoparticles were composed of Ni and NiO, as revealed by energy dispersive X-ray spectroscopy (EDX) and X-ray powder diffraction (XRD). In application to nonenzymatic glucose determination, the renewable NiCFP electrodes, which were constructed by simply mixing the electrospun nanocomposite with mineral oil, exhibited strong and fast amperometric response without being poisoned by chloride ions. Low detection limit of 1 mu M with wide linear range from 2 mu M to 2.5 mM (R = 0.9997) could be obtained.

Electrochemical Detection of Hydrazine Based on Electrospun Palladium Nanoparticle/Carbon Nanofibers

In this work, we developed an electrochemical method for the detection of hydrazine based oil palladium nanoparticle/carbon nanofibers (Pd/CNFs). Pd/CNFs were prepared by electrospinning technique and subsequent thermal treatments. The electrocatalytic behaviors of Pd/CNFs modified glassy carbon electrode (Pd/CNF-GCE) for hydrazine oxidation were evaluated by cyclic voltammetry (CV), an obvious and well-defined oxidation peak appeared at -0.32 V (vs. Ag/AgCl). The mechanism of the oxidation of hydrazine at Pd/CNF-GCE was also studied, which demonstrated an irreversible diffusion-controlled electrode process and a four-electron transfer involved in the overall reaction. Furthermore, the wide linear range, low detection limit, good reproducibility and excellent storage stability were obtained utilizing differential pulse voltammetry (DPV).