Electrospun composite fibers of polyvinylpyrrolidone with embedded poly(methyl methacrylate)–polyethyleneimine core–shell particles

Composite fibers consisting of poly(methyl methacrylate)–polyethyleneimine (PMMA–PEI) core–shell particles embedded in polyvinylpyrrolidone (PVP) were successfully fabricated by the electrospinning method. The electrospun fibers were produced using 18?% w/v aqueous PVP solution blended with 2?% w/v PMMA–PEI particles at various pH (1, 2, 3, and 4) with a fiber collection distance set at 10?cm. The applied electrical voltages (10, 12, 14, and 16?kV) significantly affected the morphology and diameter of the prepared composite fibers (141–353?nm). The smallest composite fibers were obtained from the spinning mixture at pH 2 and a voltage of 14?kV. The composite fibers would potentially be applied as drug and bioactive compound carriers.     

Electrospinning silica/polyvinylpyrrolidone composite nanofibers

Small diameter nanofibers of silica and silica/polymer are produced by electrospinning silica/polyvinylpyrrolidone (SiO₂/PVP) mixtures composed of silica nanoparticles dispersed in polyvinylpyrrolidone solutions. By controlling various parameters, 380 ± 100 nm diameter composite nanofibers were obtained with a high silica concentration (57.14%). When the polymer concentration was low, “beads‐on‐a‐string” morphology resulted. Nanofiber morphology was affected by applied voltage and relative humidity. Tip‐to‐collector distance did not affect the nanofiber diameter or morphology, but it did affect the area and thickness of the mat. Heat treatment of the composite nanofibers at 200°C crosslinked the polymer yielding solvent‐resistant composite nanofibers, while heating at 465°C calcined and selectively removed the polymer from the composite. Crosslinking did not change the nanofiber diameter, while calcined nanofibers decreased in diameter (300 ± 90 nm) and increased in surface area to volume ratio. Nanofibers were characterized by scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40966.     

Preparation of ultrafine fast‐dissolving cholecalciferol‐loaded poly(vinyl pyrrolidone) fiber mats via electrospinning

This study presents a method for incorporating cholecalciferol of a poorly water‐soluble vitamin into poly(vinyl pyrrolidone) fibers by electrospinning. The poorly water‐soluble vitamin was incorporated into water‐soluble polymeric matrix of nanofibers with the rapid evaporation of solvent during the electrospinning process. The scanning electron microscope (SEM) images showed that the diameter of nanofibers is range of 0.2‐2.9 μm. The physicochemical properties of the composite nanofibers were characterized by using Fourier‐transform infrared (FTIR) spectroscopy and Differential scanning calorimetry (DSC). 82.1 % and 51.9 % of cholecalciferol was released in the first 20 s from the composite nanofibers with a drug‐to‐PVP ratio of 1:4 and 1:2, respectively. POLYM. COMPOS., 2013 © 2013 Society of Plastics Engineers     

Synthesis and characterization of PVP/LiCoO2 nanofibers by electrospinning route

We have successfully prepared PVP/LiCoO₂ nanofibers using an electrospinning route. These fibers were composed of very small crystalline grains uniformly linked with an average size. After annealing of the above precursor fibers at 700°C for 12 h, LiCoO₂ nanofibers with 95 nm in diameter were composed of crystalline nanoparticles were successfully obtained. The morphology, crystal structure, and particle size of fibers has been characterized by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), X‐ray diffraction (XRD). The viscosities of solutions were measured with a LVDV Brookfield viscometer. Experimental results showed that the LiCoO₂ with good crystalline and uniform diameter were obtained. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A facile approach to fabricate porous nylon 6 nanofibers using silica nanotemplate

Porous Nylon 6 nanofibers were prepared using silica nanoparticles as the template. Firstly, Nylon 6/silica composite nanofibers were prepared as precursors by electrospinning Nylon 6 solutions containing different contents of silica nanoparticles. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to examine the surface morphology and the inner structure of composite nanofibers; where it was found that silica nanoparticles were distributed both inside and on the surface of nanofibers. Analytical techniques [Fourier transform infrared (FTIR), differential scanning calorimetry, thermal gravimetric analysis (TGA), and wide‐angle X‐ray diffraction) were used to study the structure and properties of these composite nanofibers. The glass transition, melting, and crystallization processes of the fibers were affected by the addition of silica nanoparticles. Secondly, porous Nylon 6 nanofibers were obtained by removing silica nanoparticles via hydrofluoric acid treatment. The removal of silica nanoparticles was confirmed using FTIR and TGA tests. SEM and TEM observations revealed the formation of the porous structure in these nanofibers. After the formation of the porous structure, Brunauer–Emmett–Teller specific surface areas of nanofibers were increased as compared to solid Nylon 6 and composite nanofibers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Helical peanut-shaped poly(vinyl pyrrolidone) ribbons generated by electrospinning

This paper describes the preparation and understanding of helical peanut-shaped ribbons of poly(vinyl pyrrolidone) (PVP) by a magnetic field-assisted electrospinning method. The relative humidity is found to significantly influence the morphology of PVP fibers. The morphology changed from straight rods to helical ribbons as relative humidity decreased. The percentage of helical ribbons increased dramatically as well. At the same time, the cross-section of electrospun fibers changed from circle, to ellipse, and to peanut shape. Formation of helical ribbons is attributed to the synergistic interaction of bending instability and rigidity of the polymers during the electrospinning process. These fibers had different mechanical properties and the helical ribbons were shown to have the largest ultimate elongation.     

Effects of hard and soft components on the structure formation,crystallization behavior and mechanical properties of electrospun poly(l-lactic acid) nanofibers

The effects of multi-wall carbon nanotubes (MWCNTs) and poly(ethylene oxide) (PEO) on the structure formation, morphology, crystallization behavior and mechanical property of electrospun poly (l-lactic acid) (PLLA) nanofiber mats were investigated by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), differential scanning calorimeter (DSC) and mechanical test. If incorporate hard filler, MWCNTs into electrospun PLLA nanofiber, the crystallinity, chain orientation, and crystallization behaviors were almost not influenced by the MWCNTs content owing to the MWCNTs mainly acted as impeding the crystal growth and chain diffusion. If incorporate small content of soft and miscible component, PEO (10 wt%) into the electrospun PLLA and PLLA/MWCNTs nanofibers, the crystallinity and crystallization rate of PLLA in nanofibers were obviously enhanced. The synergistic effect of PEO and MWCNTs in PLLA nanofibers was observed during melt-crystallization behaviors of PLLA/MWCNTs fibers. Based on those results, we found that the chain mobility is an important factor to influence the structure formation and crystallization behaviors in the electrospun nanofibers. Our results indicated that the structure and properties of electrospun nanofibers could be optimized by compounding with hard inorganic filler and soft polymer components.     

Synthesis and optimization of barium manganate nanofibers by electrospinning

Barium manganate nanofibers were successfully synthesized for the first time after heat treatment of composite nanofibers of polyvinyl pyrrolidone (PVP), barium acetate and manganese acetate using electrospinning technique. Different PVP concentrations were used and the results show that PVP concentration had played important role in the formation, uniformity, homogeneity and particularly in the reduction of nanofibers diameter. Crystal structure, microstructure, elemental analysis and surface morphology were studied using X-ray diffraction analysis, scanning electron microscopy, energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy. X-ray diffraction results show that at low temperature there is no crystallinity in the fibers sample and at ∼400 °C formations of barium manganate crystalline phase starts and finally at 700 °C all the nanofibers became single phase. The first two high intensity peaks (1 0 1) and (1 1 0) give an average crystallite size of about 20 nm. The scanning electron micrographs show that the morphology of the fibers is smooth and uniform at low temperature and become slightly porous at intermediate temperature and finally at high temperature of 700 °C the fibers become highly porous, shrank and their average diameter reduced from ∼400 nm to about 100 nm. These fibers are made of grains with sizes ranging from 15 to 30 nm. Energy dispersive X-ray spectroscopy and Fourier transform infra-red results are also in good agreement with XRD and SEM results.     

Low Temperature Carbothermal Reduction Synthesis of ZrC Nanofibers via Cyclized Electrospun PVP/Zr(OPr)4 Hybrid

The fabrication capability of zirconium carbide (ZrC) nanofibers by a novel polymeric solution was examined using electrospinning method. The electrospinnable solution was prepared from the reaction of zirconium n‐propoxide (Zr(OPr)₄) with acetylacetone and acetic acid followed by the addition of polyvinylpyrrolidone (PVP) solution. By utilizing thermal and microstructural analyses such as differential scanning calorimetry–thermogravimetry (DSC–TG), field emission scanning electron microscopy (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET), the effect of heat treatment type on the morphology and crystallinity of as‐spun PVP/Zr(OPr)₄ hybrid fibers was examined. The results showed that direct carbonization treatment of as‐spun fibers under argon atmosphere led to spherical ZrC aggregates in lack of fibrillar morphology, whereas carbonization coupled with cyclization could be recognized as the unique template to govern the morphology and crystallinity of ZrC nanofibers. Carbonization of the cyclized fibers at 1550°C in flowing argon atmosphere produced the thick, fragmented rosary‐like fibers with a diameter of 357 nm, while through a 100°C decrease in carbonization temperature to 1450°C, the thin, smooth, long, and uniform ZrC nanofibers with 176 nm diameter and a medium surface area of 23 m²/g were obtained.     

Effect of evaporation and solidification of the charged jet in electrospinning of poly(ethylene oxide) aqueous solution

The electrospinning process uses electrical force to produce nanofibers. A charged droplet acquires a conical shape known as the Taylor cone and then becomes unstable. A charged jet emerges from the vertex and develops a spiral path due to the electrically driven bending instability, which makes it possible, in a small space, for the jet to elongate by a large amount and produce nanofibers. Evaporation and the associated solidification were identified as important factors that affect the diameter of electrospun nanofibers. In this study, the evaporation rate and solidification of the charged jet were controlled by varying the relative humidity during electrospinning of poly(ethylene oxide) from aqueous solution. As the relative humidity increased, the solidification process became slower, allowing elongation of the charged jet to continue longer and thereby to form thinner fibers. As the relative humidity increased from 5.1% to 48.7%, the diameter of the solidified fiber decreased from 253 nm to 144 nm. As the relative humidity increased above 50%, beads formed on the thinner fibers, indicating that the capillary instability occurred before the jet solidified. The vapor concentration of solvent is an effective electrospinning process control parameter of fiber diameter that also produces a systematic change in the development of beads on the fibers.     

聚合物对烷基苯磺酸钠与钙离子相互作用的影响

用浊度法研究了聚合物对烷基苯磺酸钠与钙离子的相互作用的影响,不同聚合物,如聚乙烯亚胺（ＰＥＩ）、聚乙烯吡咯烷酮（ＰＶＰ）和聚乙二醇（ＰＥＧ）在同一ｐＨ条件下的研究结果表明,ＰＥＩ比后两能更好地抑制ＬＡＳ钙盐的形成。同时一聚合物在不同ｐＨ条件下的研究发现,ＰＥＩ只有在一个适当的ｐＨ范围内,即自身具有适当的电荷密度,才能很好地发挥其上述作用。在体系中存在一定量的ＡＥＯ３条件下,也观察到了ＰＥＩ在抑制     

PEI微孔纤维及PMMA/PEI复合纳米纤维的制备与表征

利用静电纺丝技术制备了具有微孔结构的聚醚酰亚胺(PEI)纳米纤维,在此基础上采用同轴共纺技术获得了有机玻璃/聚醚酰亚胺(PMMA/PEI)纳米复合纤维,考察了不同的纺丝工艺参数对PEI和PMMA/PEI纤维形貌的影响. 实验结果表明,在低浓度下单纺可获得直径0.05~0.5 mm的PEI微孔纳米纤维,使用同轴共纺技术能获得表面光滑的PMMA/PEI复合纳米纤维;经过4 MPa压置处理10 min的复合纳米纤维薄膜的拉伸强度随PEI含量的增加有所提升.     

Preparation of PEI nanofiber membrane based on in situ and solution crosslinking technology and their adsorption properties

Two kinds of PEI (Polyethyleneimine) nanofibers membrane were successfully prepared by electrospinning and crosslinking technology, which were insoluble in water. One Polyethyleneimine/ Epichlorohydrin/ Polyacrylonitrile nanofibrous films (abbreviated as PEI/ EPI/ PAN NFs) was prepared by in situ crosslinking of PEI/PAN nanofiber containing of EPI, and the other PEI/ PAN/ EPI NFs was prepared by crosslinking PEI/ PAN nanofibers using EPI solution. The composition and morphology of nanofibers before and after crosslinking were investigated by infrared spectroscopy and scanning electron microscopy. PEI/EPI/PAN nanofibers exhibited excellent adsorption properties toward heavy metal ions and methyl orange dyes, which can also be reused multiple times. The adsorption rate of methyl orange remained around 75% after 4 cycles, meanwhile, the adsorption rate of copper and lead still remained around 90% after 5 cycles. In addition, we found that PEI/ PAN/ EPI nanofibers prepared by solution crosslinking technology solved the problem of easy gel formation in in situ crosslinking technology and facilitated the continuous production of PEI/ EPI/ PAN nanofibers, which is better than in situ crosslinking technology. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48279.     

Preparation and characterization of electrospun poly(ε‐caprolactone)/poly(vinyl pyrrolidone) nanofiber composites containing silver particles

A nanofiber membrane composed of poly(ε‐caprolactone) (PCL), poly(vinyl pyrrolidone) (PVP), and silver nanoparticles was prepared via electrospinning technique. The morphology and structure of the PCL/PVP/Ag nanofibers composite were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR), X‐ray diffraction (XRD), and X‐ray photoelectron spectroscopy (XPS). The SEM images showed that various composites of PCL/PVP/Ag could be electrospun to yield continuous and uniform nanofibers. FTIR spectra indicated that the molecular interactions between PCL and PVP are weak. The hydrophilicity, mechanical property, and swelling behavior of the as‐spun composites can be manipulated by altering the blend ratio of PCL/PVP. XRD patterns and XPS spectra showed that the Ag nanoparticles were dispersed in the PCL/PVP nanofiber composites; and the Ag nanoparticles endowed the PCL/PVP/Ag composite with antibacterial activities. The obtained PCL/PVP/Ag nanofiber composites with the morphology similar to that of native extracellular matrix have the potential to create a moist environment and to kill bacteria, which make it possible to be used for wound dressing application. POLYM. COMPOS., 37:2847–2854, 2016. © 2015 Society of Plastics Engineers     

High stability of photoinduced merocyanine in naphthopyran‐doped polyvinylpyrrolidone electrospun nanofibers

Highly stable merocyanines (MCs) of naphthopyrans based on polyvinylpyrrolidone (PVP) nanofibers have been developed by electrospinning mixtures of PVP and naphthopyran derivatives. The surface and internal features of the electrospun fibers were characterized using scanning electron microscopy and Fourier transform infrared spectroscopy. The naphthopyrans displayed normal photochromic performance in the polymeric fibers and presented high‐stability MC forms. The one‐dimensional structure of the nanofibers and hydrogen bonds between PVP and MC structures of naphthopyran were responsible for the high degree of stability. The absorption intensities of the most highly stable MC form were 77% compared with the initial intensity after fading for three days. © 2014 Society of Chemical Industry     

Study of electrospun polyacrylonitrile fibers with porous and ultrafine nanofibril structures: Effect of stabilization treatment on the resulting carbonized structure

Electrospun polyacrylonitrile (PAN)-based carbon nanofibers (CNFs) with high surface area have been of promising interest because of their potential for applications in various fields, especially energy devices. In this study, PAN nanofibers with porous and ultrafine nanofiber structures were prepared by electrospinning PAN/poly(vinyl pyrrolidone) (PVP) immiscible solutions and then selectively removing the PVP component from the electrospun PAN/PVP bicomponent nanofibers. The chemical reaction and microstructure of the PAN fibers with porous and ultrafine nanofibril structures in the stabilization process were investigated. The results revealed the effects of PAN fibers with porous and ultrafine nanofibril structures on the crosslinking reaction, microstructure, and morphology during the stabilization process. According to the in situ Fourier transform infrared spectroscopy results, the intermolecular and intramolecular reactions of the nitrile group for the PAN fibers with ultrafine nanofibril structures exhibited slower reaction rates than those for the neat PAN fibers during stepwise and isothermal heating. Selecting a good stabilization temperature for ultrafine PAN-crosslinked nanofibrils can enhance the surface area and carbonized structure of CNFs. The possible applications of CNFs with porous and ultrafine nanofibril structures in supercapacitors were also evaluated. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 48218.     

Fabrication of Tuneable Thickness Silica Films on Solid Surfaces Using Amines and Proteins

We report an elegant and simple method to fabricate silica films with controlled thickness and roughness using protein coated solid surfaces as substrates. Bovine serum albumin (BSA) and lysozyme having different inherent charges have been used as model proteins (templates) to fabricate silica films. The formation of silica films was achieved by immobilization of BSA and lysozyme on amine (poly(allylamine) (PAH), poly(ethyleneimine) (PEI) and octadecyl amine (ODA)), coated surfaces, followed by treatment with silica precursors (tetramethoxysilane) under environmentally benign conditions of pH and temperature. BSA adsorbs strongly on hydrophilic surfaces (PAH and PEI coated) via electrostatic interaction, while lysozyme shows greater affinity towards hydrophobic surfaces (ODA coated) via largely hydrophobic interactions. The thickness (12–60 nm) and roughness of the films (1.30–3.75 nm) could be tuned by varying the amount of the adsorbed proteins on the amine-coated surfaces. This simple route to prepare silica films of controlled thickness could have potential application in membrane fabrication, biomedical devices, biosensors and next generation electronic components.     

Fabrication of discontinuous fibers of poly (N‐vinylpyrrolidone) containing metalloporphyrin molecules

This study described the preparation of discontinuous fibers of poly (N‐vinylpyrrolidone) (PVP) containing metalloporphyrin (Manganese (III) tetrakis (1‐methyl‐4‐pyridyl) porphyrin pentachloride) molecules using electrospinning method. SEM images showed that before adding the metalloporphyrin molecules, the electrospun nanofibers are straight and smooth, while after adding metalloporphyrin molecules into the PVP solutions, the SEM images clearly showed that there were two different types of fibers: the thinner fibrous phase and the thicker discontinuous fibers. The chemical composition of the resulting PVP/metalloporphyrin composite fibers was characterized by Fourier‐transform infrared (FTIR) and energy dispersive X‐ray (EDX) analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 6017–6022, 2006     

Amorphous SiCNO hollow nanofibers with mesoporous walls

In this work, for the first time, we reported the fabrication of polymer-derived amorphous SiCNO ceramics via electrospinning of tetraethoxysilane (TBOS), polyvinylpyrrolidone (PVP), cetrimonium bromide (CTAB), and urea combined with subsequent air calcination. The resultant products exhibited a well-defined one-dimensional (1D) hollow fiber nanostructure with mesoporous walls. The BET surface area of SiCNO hollow nanofibers is ~95.6 m²/g, and the average pore diameter is sized in ~9 nm. The movement of urea within the core of the as-spun polymeric fibers accounted for the formation of hollow nanofibers, and the thermal decomposition of polymers such as PVP, TEOS, and urea responded for the formation of mesopores within the walls. In addition, it was found that the contents of urea within the raw materials played a critically important role in the formation of SiCNO mesoporous hollow nanofibers, making their growth in a controlled manner.     

Preparation of monodispersed silica spheres and electrospinning of poly(vinyl alcohol)/silica composite nanofibers

In this study, monodispersed silica spheres were successfully synthesized by seed‐growth method and they can be highly dispersed in the poly(vinyl alcohol)(PVA) solution. PVA/silica composite fibers were fabricated by electrospinning the composite solutions containing different amount of silica. Further investigation showed that the size distribution of silica sphere was monodispersed and the spheres were homogeneously dispersed in the fibers individually. The composite fibers showed an uniform and continuous morphology with a average diameter of 298–345 nm. The as‐spun nanofibers were characterized by Field Emission Scanning Electron Microscope (FE‐SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), and thermal gravimetric analysis (TGA). POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers