Structurally modified electrospun poly(methyl methacrylate) nanofibers as advanced host matrices for PbS quantum dots

The present work deals with the studies of the host matrix nature of pure and structurally modified surface roughened and coaxial hollow electrospun poly(methyl methacrylate) (PMMA) nanofibers to lead sulphide (PbS) quantum dots. The various structural and molecular analyses conducted on these samples proved the advancements and structural modifications made in the properties of pure PMMA nanofibers by electrospinning and selective dissolution. The successful incorporation of the quantum dots to pure and structurally modified PMMA nanofibers and hence the host matrix nature of these nanofibers is proved by different spectral analyses of the samples. The coaxial hollow PMMA nanofibers are found to be the best host matrix among these PMMA nanofibers as proved by the optical studies of the samples. Photoluminescence analyses of the samples showed the influence of these quantum dots on the optical properties of PMMA nanofibers. It is observed here that, the quantum dots enhance the intensity of coaxial hollow PMMA nanofibers to about four times than its virgin form. The pure and structurally modified PMMA nanofibers incorporated with PbS quantum dots are proved to be efficient for the degradation of methylene blue dye where coaxial hollow PMMA nanofibers incorporated with PbS quantum dots is the best.     

TiO_2/SiO_2复合纳米纤维的GQDs改性及其对甲醛的可见光催化降解性能

采用静电纺丝法合成了TiO_2/SiO_2柔性复合纳米纤维膜,而后对其进行石墨烯量子点(GQDs)改性,制备了GQDs/TiO_2-SiO_2复合纳米纤维,其中GQDs用水热法合成。用X射线衍射仪(XRD)、电子万能材料试验机、扫描电子显微镜(SEM)、紫外-可见分光光度计(UV-Vis)对其物相组成、力学性能、微观形貌以及光催化性能进行了表征。结果表明:尺寸在7 nm~15 nm之间的GQDs松散沉积在直径为200 nm~400 nm的TiO_2/SiO_2纳米纤维上,纤维连续性好,复合薄膜有较好的力学性能;TiO_2的结晶较好,为锐钛矿相;GQDs复合后将TiO_2的本征吸收从390 nm左右延伸到了420 nm左右,拓宽了TiO_2的吸收范围。在可见光催化降解中,初始浓度为0.32 mg/m~3的甲醛气体110 min后的降解效率达到70%。     

ZnO nanocrystallites/cellulose hybrid nanofibers fabricated by electrospinning and solvothermal techniques and their photocatalytic activity

ZnO nanocrystallites have been in situ embedded in cellulose nanofibers by a novel method that combines electrospinning and solvothermal techniques. Zn(OAc)₂/cellulose acetate (CA) precursor hybrid nanofibers with diameter in the range of 160–330 nm were first fabricated via the electrospinning technique using zinc acetate as precursor, CA as the carrier, and dimethylformamide (DMF)/acetone(2 : 1) mixture as cosolvent. The precursor nanofibers were transformed into ZnO/cellulose hybrid fibers by hydrolysis in 0.1 mol/L NaOH aqueous solution. Subsequently, these hybrid fibers were further solvothermally treated in 180°C glycerol oil bath to improve the crystallite structure of the ZnO nanoparticles containing in the nanofibers. The structure and morphology of nanofibers were characterized by scanning electron microscopy, transmission electron microscopy, and X‐ray diffraction. It was found that hexagonal structured ZnO nanocrystallites with the size of ～ 30 nm were dispersed on the nanofiber surfaces and within the nanofibers with diameter of about 80 nm. The photocatalytic property of the ZnO/cellulose hybrid nanofibers toward Rhodamine (RhB) was tested under the irradiation of visible light. As a catalyst, it inherits not only the photocatalytic ability of nano‐ZnO, but also the thermal stability, good mechanical property, and solvent‐resistibility of cellulose nanofibers. The key advantages of this hybrid nanofiber over neat ZnO nanoparticles are its elasticity, dimensional stability, durability, and easy recyclability. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication of Multifunctional Composite Nanofibers by Green Electrospinning

The present work takes advantage of green electrospinning to create novel composite multifunctional nanofibers (NFs) bearing inorganic nanoparticles (NPs), more specifically quantum dots (QDs), cerium oxide nanoparticles (CeO₂ NPs) and iron oxide nanoparticles (Fe₃O₄ NPs). This is achieved by first encapsulating the desired inorganic NPs into polymer particles by the use of miniemulsion polymerization, and second, spinning the hybrid polymer particles using polyvinyl alcohol (PVA) as template polymer. It is proved that using green electrospinning, it is not only possible to ensure an excellent distribution and encapsulation of the inorganic NPs along the NFs, but also allows to control and change the concentration, size, and type of the inorganic NPs without altering the NFs size, a fact that is not possible by conventional solution electrospinning. As proof of concept, NFs with up to three different types of inorganic NPs have been created in a single electrospinning step, but this technology allows to incorporate as much inorganic NPs as desired without altering the NFs morphology and ensuring a good distribution and encapsulation of the NPs. This paper demonstrates that green electrospinning is a powerful and attractive technology to create multifunctional NFs that are promising materials for sensing and biomedical applications.     

氟树脂/聚丙烯酸酯胶乳型互穿网络的合成

采用原位聚合和互穿网络的方法,以氟树脂乳液作种子乳液,氟碳乳化剂和碳氢乳化剂为复配乳化剂,合成了聚丙烯酸酯和氟树脂胶乳型互穿网络聚合物(LIPN),所合成的乳液稳定性良好。通过对聚合物的微观形态、动态机械力学性能和接触角的分析,表明用此方法乳液聚合,可以较好地改善两种树脂的相容性,聚合物的表面能有了较大的下降。     

Fabrication and characterization of 3-dimensional PLGA nanofiber/microfiber composite scaffolds

Novel three-dimensional (3-D) nano-/microfibrous poly(lactic-co-glycolic acid) (PLGA) scaffolds were fabricated by hybrid electrospinning, involving a combination of solution electrospinning and melt electrospinning. The scaffolds consisted of a randomly oriented structure of PLGA microfibers (average fiber diameter = 28 μm) and PLGA nanofibers (average fiber diameter = 530 nm). From mercury porosimetry, the PLGA nano-/microfiber (10/90) scaffolds were found to have similar pore parameters to the PLGA microfiber scaffolds. PLGA nano-/microfibrous scaffolds were examined and compared with the PLGA microfiber scaffolds in terms of the attachment, spreading and infiltration of normal human epidermal keratinocytes (NHEK) and fibroblasts (NHEF). The cell attachment and spreading of both cell types were several times higher in the nano-/microfiber composite scaffolds than in the microfibrous scaffolds without nanofibers. This shows that the presence of nanofibers enhanced the attachment and spreading of the cells on the nano-/microfiber composite scaffolds. Moreover, the nanofibers helped the cells infiltrate easily into the scaffolds. Overall, this novel nano-/microfiber structures has great potential for the 3-D organization and guidance of cells provided for tissue engineering.     

Mn2O3/TiO2 nanofibers with broad-spectrum antibiotics effect and photocatalytic activity for preliminary stage of water desalination

Composite nanofibers consisting of Mn₂O₃ and TiO₂ were prepared by the electrospinning process, and tested as Gram-class-independent antibacterial agent and photocatalyst for organic pollutants degradation. Initially, electrospinning of a sol–gel consisting of titanium isopropoxide, manganese acetate tetrahydrate and poly(vinyl pyrrolidone) was used to produce hybrid polymeric nanofibers. Calcination of the obtained nanofibers in air at 650 °C led to produce good morphology Mn₂O₃/TiO₂ nanofibers. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were employed to characterize the as-spun nanofibers and the calcined product. X-ray powder diffractometry (XRD) analysis was also used to characterize the chemical composition and the crystallographic structure of the sintered nanofibers. The antibacterial activity of Mn₂O₃/TiO₂ nanofibers against Gram negative and Gram positive bacteria was investigated by calculating the minimum inhibitory concentration after treatment with the nanofibers. Investigations revealed that the lowest concentration of Mn₂O₃/TiO₂ nanofibers solution inhibiting the growth of Staphylococcus aureus ATCC 29231 and Escherichia coli ATCC 52922 strains is 0.4 and 0.8 μg/ml, respectively. Incorporation of Mn₂O₃ significantly improved the photodegradation of methylene blue (MB) dye under the visible light irradiation due to enhancing rutile phase formation in the TiO₂ nanofibers matrix.     

Preparation of Necklace-Structured TiO2/SnO2 Hybrid Nanofibers and Their Photocatalytic Activity

TiO₂/SnO₂ nanonecklace-structured hybrid nanofibers have been prepared via an electrospinning method. These hybrid nanofibers are characterized with SnO₂-rich beads and pure TiO₂ chains. It is found that TiO₂ in the beads shows a rutile structure, and the one in the chains is entirely composed of anatase phase. This novel microstructure enhanced the photocatalytic activity, as well as its ideal recyclable character. We believe that this fire-new type of nanofiber may potentially serve as a new generation photocatalyst in environmental remediation.     

Biphasic,tough composite core/shell PCL/PVA-GEL nanofibers for biomedical application

Emulsion electrospinning using natural and synthetic polymers, including two dissimilar materials is a promising technique for nanofibers fabrication in a core/shell configuration for tissue engineering, controlled or sustained drug delivery and dressing applications. In this study, we designed and fabricated core/shell nanofibers based on polycaprolactone (PCL) as core material and poly(vinyl alcohol) (PVA)-gelatin (GEL) blend as shell materials (PCL/PVA-GEL) to achieve high mechanical properties, good cell growth, and proliferation via emulsion electrospinning. The effect of water to acetic acid ratio in the solvent system (8:2, 7:3, 6:4, 5:5) and also type and concentration (3, 5, 7 w/v %) of surfactant on emulsion stability and nanofibers morphology were investigated. The emulsion containing 2% Tween80 and 1% Span60 as surfactants were selected by considering the stability of emulsion and uniform fiber morphology. In the tensile strength and elongation at break, 53 and 8% increase in the crosslinked wet state of the PCL/PVA-GEL nanofibers compared with PVA-GEL nanofibers were observed respectively. The cell culture results indicated that the PCL/PVA-GEL nanofibers surface has presented suitable interaction with fibroblast cells and cells attached and proliferated well on the fabricated substrate within 24 and 48 hours and also would be a good candidate for biomedical applications. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48713.     

Synthesis and characterization of PVB/silica nanofibers by electrospinning process

This paper describes PVB/silica nanofibers which were fabricated by electrospinning. Although electrospinning has developed rapidly over the past few years, electrospinning nanofibers are still at a premature research stage which is a process by which polymer nanofibers can be formed when a droplet of viscoelastic polymer solution is subjected to high voltage electrostatic field. PVB/silica nanofibers were obtained when the PVB/silica precursor ratio was 15% and the average diameters ranged from 100 to 200 nm and increased with increasing solution concentration and electrospinning synthesized at 12 kV of the applied voltage. The morphologies and structures of PVB/silica nanofibers were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), Fourier transform infrared spectrometer (FTIR), energy dispersive spectrometer (EDS).     

Interior synthesizing of ZnO nanoflakes inside nylon‐6 electrospun nanofibers

Doping of the polymeric electrospun nanofibers by metal oxides nanoparticles is usually performed by electrospinning of a colloidal solution containing the metal oxide nanoparticles. Besides the economical aspects, electrospinning of colloids is not efficient compared with spinning of sol–gels, moreover well attachment of the solid nanoparticles is not guaranteed. In this study, reduction of zinc acetate could be performed inside the nylon‐6 electrospun nanofibers; so polymeric nanofibers embedding ZnO nanoflakes were obtained. Typically, zinc acetate/nylon‐6 electrospun nanofibers were treated hydrothermally at 150°C for 1 h. Besides the utilized characterization techniques, PL study affirmed formation of ZnO. The produced nanofibers showed a good antibacterial activity which improves with increasing ZnO content. Overall, the present study opens new avenue to synthesize hybrid nanofibers by a facile procedure. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation of TiO2-Pt hybrid nanofibers and their application for sensitive hydrazine detection

The TiO2-Pt hybrid nanofibers with an average dia. 72.6 nm were fabricated by electrospinning poly(vinylpyrrolidone)-ethanol solution containing platinum acetate and titanium tetraisopropoxide, followed by calcination in air at 500 °C for 3 h. High resolution TEM showed that Pt nanoparticles with an average diameter of ～2 nm were well dispersed in the anatase TiO2 nanofibers. Compared to pristine TiO2 nanofibers (average dia. 67.7 nm), the incorporation of Pt nanoparticles into TiO2 nanofibers can greatly enhance the oxidation of hydrazine in neutral solution. The amperometric hydrazine sensor, using the as-prepared TiO2-Pt hybrid nanofibers as the electrochemical catalyst, shows a wide linear range (up to 1.03 mM), a good limit of detection (0.142 μM), and a high sensitivity of 44.42 μA mM(-1) cm(-2). In addition, the excellent anti-interference property, free of matrix effect from real water samples and good reproducibility make the developed hydrazine sensor promising for real applications.     

Chain conformation,crystallization behavior,electrical and mechanical properties of electrospun polymer-carbon nanotube hybrid nanofibers with different orientations

An improved electrospinning technique was used to produce poly(ethylene oxide) (PEO) and PEO-multi-walled carbon nanotube (MWCNT) hybrid nanofibers. By this technique, both the orientation of MWCNTs in the electrospun PEO nanofibers and the orientation of electrospun PEO–MWCNT hybrid nanofibers can be controlled. The morphologies of the as-spun PEO–MWCNT hybrid nanofibers and the dispersion and orientation of MWCNTs in the fiber matrix were observed by scanning and transmission electron microscopy. The effect of electrospinning process and the incorporation of MWCNTs on the chain conformation and semicrystalline framework of PEO were examined by Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and differential scanning calorimetry, and compared with pure PEO and PEO–MWCNT films prepared by casting. Finally, to investigate how the fiber assemblies affect the mechanical and electrical properties of the hybrid materials, tensile testing and impedance analysis were performed on randomly oriented, uniaxially and biaxially oriented PEO–MWCNT hybrid nanofiber mats. The results indicated that both the uniaxially and biaxially oriented assembled hybrid materials have better tensile strength, modulus, and electrical conductivity compared with random nanofibers.     

Carbon/SnO2/carbon core/shell/shell hybrid nanofibers: tailored nanostructure for the anode of lithium ion batteries with high reversibility and rate capacity

A carbon/SnO(2)/carbon core/shell/shell hybrid nanofibrous mat was successfully prepared via single-spinneret electrospinning followed by carbonization and hydrothermal treatment. The morphology and structure of carbon/SnO(2)/carbon hybrid nanofibers were characterized by field-emission scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, wide-angle X-ray diffraction and X-ray photoelectron spectroscopy, and their electrochemical properties were studied as an anode in lithium ion batteries (LIBs). It is shown that the designed hybrid nanofibrous mat exhibits excellent electrochemical properties, including high reversible capacity with high columbic efficiency and impressive rate capacity. The greatly enhanced electrochemical performance is mainly due to the morphological stability and reduced diffusion resistance, which are induced by both the carbon core and deposited carbon skin. Furthermore, the embedded and de-aggregated SnO(2) nanoparticles in the carbon phase, which are less than 10 nm in size, provide large numbers of reaction sites for lithium ions and ensure complete alloying with them.     

Fabrication of Au/PVP nanofiber composites by electrospinning

Gold nanoparticles prepared by trisodium citrate reduction of HAuCl₄ in poly(vinylpyrrolidone) (PVP) ethanol solution were dispersed into PVP nanofibers by electrospinning. The optical property of Au nanoparticles before and after electrospinning was measured by UV‐Vis. The morphology and distribution of gold nanoparticles in PVP nanofibers were observed by transmission electron microscopy (TEM). The influence of the amount of Au added to and the concentration of PVP in electrospinning solution over the morphology of Au/PVP nanofibers were studied. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Fluorescent poly(p-phenylene vinylene)/poly(ethylene oxide) nanofibers obtained by electrospinning

Poly(p-phenylene vinylene) (PPV)/poly(ethylene oxide) (PEO) hybrid nanofibers were prepared by electrospinning a composite solution of PPV precursor/PEO in a mixture of ethanol and water, followed by thermal conversion. The precursor/PEO composite solutions were successfully electrospun into nanofibers with diverse helical, helical and linear, and helical bead-on-string morphologies by controlling the amount of aqueous PEO solution in a composite solution. Moreover, adding aqueous PEO solution to a precursor ethanol solution decreased the diameters of the fibers. The experimental data suggest that the viscosity, conductivity, and surface tension of the electrospinning solution are the main factors that influence the morphology of the fibers. Fourier transform infrared (FT-IR) and X-ray diffraction (XRD) investigations indicated that the PPV precursor reacts with PEO during thermal conversion. Ultraviolet–visible (UV-vis) and photoluminescence (PL) spectra of the PPV-PEO nanofibers exhibited appreciable blue shifts with the addition of PEO, which made it possible to fabricate nanofibers with fluorescence ranging from yellow-green to blue. These highly fluorescent PPV/PEO nanofibers with various morphologies are potentially interesting for many applications, such as micro- and nanooptoelectronic devices and systems.     

含纳米铝粉的纳米NC纤维的制备

为了克服纳米铝粉在推进剂使用过程中分散不均匀的问题,采用静电纺丝技术制备了材料表面光滑、直径均匀、且纳米铝粉分散均匀的纳米NC纤维.用扫描电镜研究了含水率、溶液浓度、电压和挤出速率对纤维形态和直径的影响,得到静电纺丝最佳工艺条件:含水率为10%～15%,NC纺丝液质量分数5%～10%,电压25～30kV,挤出速率0.5...     

气流-静电纺丝法制备P(AN-co-AA)纳米纤维的研究

用气流-静电纺丝法制备了丙烯腈-丙烯酸共聚物[P(AN-co-AA)]纳米纤维。通过扫描电镜(SEM)对纳米纤维形貌的表征,研究了聚合时丙烯酸(AA)单体的含量、溶剂种类以及工艺参数对P(AN-co-AA)纳米纤维直径和形貌的影响,得到了最佳工艺条件为:纺丝溶剂N、N-二甲基甲酰胺(DMF)、聚合单体中AA的摩尔分数比15%、P(AN-co-AA)质量分数10%、外加电压20kV、接收距离20cm,所得P(AN-co-AA)纳米纤维的平均直径为156nm。     

Electrospun antibacterial nylon nanofibers through in situ synthesis of nanosilver: preparation and characteristics

A new method for production of nylon nanofibers with antibacterial properties containing silver nanoparticles (nylon nanofibers/Ag NPs) is introduced via in situ synthesis of nano-silver by reduction of silver nitrate in the polymer solution prior to electrospinning. The properties of the electrospinning solutions and the structures of the electrospun fibers were studied using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDAX), UV?Cvis spectrophotometer and reflection spectrophotometer. Further, the antibacterial properties of the nanofibers were investigated against Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive) bacteria. Interestingly, an antibacterial properties has been found on nylon 6 nanofibers while the nylon nanofibers/Ag NPs showed excellent antibacterial activities against both tested bacteria. The produced nylon nanofibers/Ag NPs can be a good candidate for biomedical applications, water and air filtration.     

Characterization of PVAc/TiO2 hybrid nanofibers: From fibrous morphologies to molecular structures

Polyvinyl acetate (PVAc)/titanium dioxide (TiO₂) hybrid nanofibers were fabricated by combining sol–gel process with electrospinning technology, which consisted of PVAc as organic segment and TiO₂ as inorganic part. The surface structures of the PVAc/TiO₂ hybrid nanofibrous mats were examined using scanning electron microscopy (SEM). The surface morphology and bulk structures of single nanofiber were investigated by atomic force microscopy (AFM) and transmission electron microscopy (TEM). Fourier transform infrared spectroscopy (FTIR) was employed to analyze the chemical structures of the PVAc/TiO₂ hybrid nanofibers. SEM scanning revealed that the fibrous structure was formed. AFM observations presented a significant difference in the morphology of the nanofibers before and after hybridization. It was observed from TEM images that some black streaks with various lengths distributed in a nanofiber. The FTIR analysis indicated the newly formed associated hydrogen bond because of the hybrid effect between PVAc and TiO₂ sol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009