Sea‐island polyurethane/polycarbonate composite nanofiber fabricated through electrospinning

Sea‐island polyurethane (PU)/polycarbonate (PC) composite nanofibers were obtained through electrospinning of partially miscible PU and PC in 3 : 7 (v/v) N,N‐dimethylformamide (DMF) and tetrahydrofuran (THF) mixture solvent. Their structures, mechanical, and thermal properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric (TG), and differential scanning calorimetry (DSC). The structures and morphologies of the nanofibers were influenced by composition ratio in the binary mixtures. The pure PC nanofiber was brittle and easy to break. With increasing the PU content in the PU/PC composite nanofibers, PU component not only facilitated the electrospinning of PC but improved the mechanical properties of PU/PC nanofibrous mats. In a series of nanofibrous mats with varied PU/PC composition ratios, PU/PC 70/30 showed excellent tensile strength of 9.60 Mpa and Young's modulus of 55 Mpa. After selective removal of PC component in PU/PC composite nanofibers by washing with acetone, the residual PU maintained fiber morphology. However, the residual PU nanofiber became irregular and contained elongated indents and ridges along the fiber surface. PU/PC composite fibers showed sea‐island nanofiber structure due to phase separation in the spinning solution and in the course of electrospinning. At PC content below 30%, the PC domains were small and evenly dispersed in the composite nanofibers. As PC content was over 50%, the PC phases became large elongated aggregates dispersed in the composite nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Fabrication of blend biodegradable nanofibrous nonwoven mats via multi-jet electrospinning

A series of blend biodegradable nanofibrous mats comprising poly(vinyl alcohol) (PVA) and cellulose acetate (CA) were prepared via multi-jet electrospinning. A relative high voltage (20 kV) was used to supply the power for multi-jet electrospinning. The weight ratio of PVA/CA in blend nanofibrous mats can be controlled by changing the number ratio of jets of PVA/CA. Moreover, the real composition of PVA and CA in blend nanofibrous mats was determined by immersing the blend nanofibrous mats into water to remove the PVA component. Morphology, dispersibility, and mechanical properties of blend nanofibrous mats were examined by field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectroscopy, wide-angle X-ray diffraction (WAXD), and tensile test. The results showed that the blend nanofibrous mats have good dispersibility. Additionally, the mechanical properties of blend nanofibrous mats were largely influenced by the weight ratio of PVA/CA in blends. Potential applications of the blend nanofibrous mats include filters and biomedical materials.     

ZnO Nanofiber and Nanoparticle Synthesized Through Electrospinning and Their Photocatalytic Activity Under Visible Light

In this paper, we fabricate ZnO nanofibers and nanoparticles through electrospinning precursor solution zinc acetate(ZnAc)/cellulose acetate(CA) in mixed-solvent N , N -dimethylformamide/acetone. Depending on the posttreatment of precursor ZnAc/CA composite nanofibers, both ZnO nanofibers and nanoparticles were synthesized after calcination of precursor nanofibers. The morphology and crystal structure of the ZnO nanofiber and nanoparticle were characterized by scanning electron microscopy, transmission electron microscopy, atomic force microscopy, and X-ray diffraction. It was found that the mean diameter of the ZnO nanofiber and nanoparticle was ca. 78 and 30 nm, respectively. The photo-degradation of dye molecules such as Rhodamine B and acid fuchsin catalyzed by the ZnO nanofiber and nanoparticle was evaluated under the irradiation of visible light. Both morphological ZnO species showed strong photocatalytic activity. However, the ZnO nanofiber in the form of nanofibrous mats showed much higher efficiency than the nanoparticle although the latter has a smaller size than the former. The porous structure of ZnO nanofibrous mats is believed to improve the contacting surface areas between the catalyst and the dye molecules, while the aggregation of ZnO nanoparticle in the solution lowers the photocatalytic efficiency.     

Co-electrospun cellulose diacetate-graft-poly(ethylene terephthalate) and collagen composite nanofibrous mats for cells culture

In this study, a kind of novel composite nanofibrous mats with cellulose diacetate-graft-poly(ethylene terephthalate) (CDA-g-PET) and Type I collagen were obtained by electrospinning and five different ratios of CDA-g-PET/Type I collagen (1:0, 1:0.1, 1:0.2, 1:0.3, 1:0.4) were set to explore the effects of components on its properties. The scanning electron microscope images demonstrated that the formation of uniform and smooth nanofibers with free beads. Compared with pure CDA-g-PET mats, the composite materials transformed into hydrophilic ones with increasing the content of Type I collagen. Moreover, the tensile strength of the composite nanofibrous mats got higher, while its water vapor transmission rate got lower after blending with Type I collagen. In addition, the cell proliferation and adhesion on composite nanofibrous mats were improved according by the results of bone marrow mesenchymal stem cells (BMSCs) culturing experiments. Especially, the cells growth attained optimum when the CDA-g-PET/Type I collagen ratio reached 1:0.3 and 1:0.4, where showed no significant difference. In consequence, the above results indicated that the novel composite nanofibrous mats consisted of CDA-g-PET and Type I collagen obtained by electrospinning combined good mechanical strength of CDA-g-PET and excellent biological functions of Type I collagen. The nanoscale structure might mimic the nanofibrous extracellular matrix feature, which present the potential use in cells culture.     

Electrospinning of solvent‐resistant nanofibers based on poly(acrylonitrile‐co‐glycidyl methacrylate)

This article reports on the preparation of novel solvent‐resistant nanofibers by electrospinning of poly(acrylonitrile‐co‐glycidyl methacrylate) (PANGMA) and subsequent chemical crosslinking. PANGMA nanofibers with diameters ranging from 200 to 600 nm were generated by electrospinning different solutions of PANGMA dissolved in N,N‐dimethylformamide. Different additives were added to reduce the fiber diameter and improve the morphology of the nanofibers. The as‐spun PANGMA nanofibers were crosslinked with 27 wt % aqueous ammonia solution at 50°C for 3 h to gain the solvent resistance. Swelling tests indicated that the crosslinked nanofibers swelled in several solvents but were not dissolved. The weight loss of all the crosslinked nanofibrous mats immersed in solvents for more than 72 h was very low. The characterization by electron microscopy revealed that the nanofibrous mats maintained their structure. This was also confirmed by the results of the pore size measurements. These novel nanofibers are considered to have a great potential as supports for the immobilization of homogeneous catalysts and enzymes. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Electrospun salicylic acid/polyurethane composite nanofibers for biomedical applications

Salicylic acid (SA)/polyurethane (PU) composite nanofiber mats were fabricated by introducing SA in PU solution during the electrospinning process. Cell viability assays showed that the as-prepared composite nanofibers had a good biocompatibility. Further, the composite mats showed good antibacterial performance against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. Easy fabrication, good mechanical properties, good biocompatibility as well as the antibacterial activity of PU nanofibers containing SA indicated their significant promise for a variety of potential medical applications such as tissue engineering, wound healing, and drug delivery system.     

Coaxial electrospinning of PC(shell)/PU(core) composite nanofibers for textile application

To develop a novel functional composite material for textile application, a coaxial electrospinning technique was investigated to electrospin two different polymer solutions into core‐shell structured nanofibers in which polyurethane and polycarbonate were used as core and shell materials, respectively. The resultant nanofibers were subsequently characterized by means of scanning electron microscope, transmission electron microscopy, fourier transform infrared spectroscopy, and tensile mechanical test. Furthermore, water vapour transmission rate and pliability of the resulting nonwoven mats were also measured. The preliminary results indicated that it is feasible to attach composite nanofibers, with possible fictionalization on the shell material, onto a substrate fabric. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Facile preparation and characterization of poly(vinyl alcohol)/chitosan/graphene oxide biocomposite nanofibers

Poly(vinyl alcohol) (PVA)/chitosan (CS)/graphene oxide (GO) biocomposite nanofibers have been successfully prepared using aqueous solution by electrospinning. CS colloidal gel in 1% acetic acid can be changed to homogeneous solution by using electron beam irradiation (EBI). The uniform distributions of GO sheets in the nanofibers were investigated by field emission scanning electron microscopy (FESEM) and Raman spectroscopy. FESEM images illustrated that the spread single GO sheet embedding into nanofibers was formed via self-assembly of GO sheet and PVA/CS chains. And the average diameters of the biocomposite nanofibers decreased (200, 173, 160 and 123 nm) with increasing the contents of GO (0.05, 0.2, 0.4 and 0.6 wt%). Raman spectra verified the presence of GO in the biocomposite nanofibrous mats. The mechanical properties of as-prepared materials related with GO contents. It revealed that the highest tensile strength was 2.78 MPa, which was 25% higher than that of neat PVA/CS nanofibers. Antibacterial test demonstrated that the addition of GO to PVA/CS nanofiber had great ability to increase inhibition zone till 8.6 mm. Overall, these features of PVA/CS/GO nanofibers which were prepared by eco-friendly solvent can be a promising candidate material in tissue engineering, wound healing and drug delivery system.     

Electrospun cellulose nanofiber reinforced soybean protein isolate composite film

This article presents the fabrication of cellulose nanofibrous mats (CNM) reinforced soybean protein isolate (SPI) composite with high visible light transmittance. The CNM was composed of cellulose nanofibers generated from electrospinning technique. The microstructure of the fractured surface of composite films was characterized by scanning electron microscopy (SEM). The light transmittance, mechanical properties, and swelling ratio of CNM/SPI composite were investigated in terms of CNM content in the composite. Because of the ultrafine diameter and superhigh length‐to‐diameter ratio of nanofibers, large amount of cellulose nanofibers fibers distribute in the SPI matrix to form an interpenetrating network (IPN) like composite material. It was found that strong interfacial interactions occurred at the cellulose nanofiber/SPI interfaces. The incorporation of 20 wt % cellulose nanofibers in the SPI matrix resulted in great improvement of mechanical strength and Young's modulus by respectively 13 and 6 times more than neat SPI film. More interestingly, this composite was translucent with light transmittance of over 75% at 700 nm. Furthermore, the swelling ratio of this IPN‐like CNM/SPI composite decreased from 106 to 22% as CNM content increased from 0 to 20 wt %. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation of carboxymethyl chitosan nanofibers through electrospinning the ball-milled nanopowders with poly (lactic acid) and the blood compatibility of the electrospun NCMC/PLA mats

Carboxymethyl chitosan was pulverized to nanopowder (NCMC) with a diameter of 483 nm through ball-milling. 400 mg NCMC was successfully electrospun to nanofibers with the assistant of 4 g poly (lactic acid) (PLA) to prepare NCMC/PLA nanofibrous composite mats. Scanning electron microscope images revealed that there were no NCMC particles in the NCMC/PLA mats, indicating NCMC had been stretched to nanofibers. NCMC/PLA mats with different morphology could be prepared through adjusting the electrospinning voltage at 12–30 kV and the distance at 10–22 cm. The presence of NCMC increased the spinnability of PLA according to the electrospinning parameters. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy verified the existence of NCMC in the mats. Crosslinking with glutaraldehyde increased the stability of NCMC/PLA in water. Crosslinked NCMC/PLA mats expressed good blood compatibility according to the results of blood clotting time and platelet adhesion experiment. The methodology of preparation nanofibers from polymer nanopowders through electrospinning could be used to prepare more composite nanofibers while adopting different raw materials.     

Conjugate electrospinning of continuous nanofiber yarn of poly(L‐lactide)/nanotricalcium phosphate nanocomposite

The continuous nanofiber yarns of poly(L ‐lactide) (PLLA)/nano‐β‐tricalcium phosphate (n‐TCP) composite are prepared from oppositely charged electrospun nanofibers by conjugate electrospinning with coupled spinnerets. The morphology and mechanical properties of PLLA/n‐TCP nanofiber yarns are characterized by scanning electron microscope, transmission electron microscope, and electronic fiber strength tester. The results show that PLLA/n‐TCP nanofibers are aligned well along the longitudinal axis of the yarn, and the concentration of PLLA plays a significant role on the diameter of the nanofibers. The thicker yarn of PLLA/n‐TCP composite with the weight ratio of 10/1 has been produced by multiple conjugate electrospinning using three pairs of spinnerets, and the yarn has tensile strength of 0.31cN/dtex. A preliminary study of cell biocompatibility suggests that PLLA/n‐TCP nanofiber yarns may be useable scaffold materials. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Effects of gamma irradiation on the thermal and mechanical properties of chitosan/PVA nanofibrous mats

Chitosan/poly(vinyl alcohol) (PVA) nanofibrous mats were prepared by the electrospinning method. The morphology and structure of electrospun nanofibers were investigated by scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. SEM images showed that the uniform and bead-free fibers were obtained at concentrations greater than 8 wt%. Chitosan/PVA mats were irradiated with different doses (50–200 kGy) of ⁶⁰Co gamma rays. The effect of irradiation dose on the mechanical and thermal properties of these films was also investigated. Increasing the irradiation dose led to a decrease in tensile strength. FT-IR and DSC demonstrated that there were strong intermolecular hydrogen bonds between the chitosan and PVA molecules.     

Fabrication of gelatin/chitosan nanofibrous scaffold: process optimization and empirical modeling

Electrospinning is a very useful technique for producing polymeric nanofibers by applying electrostatic forces. This study reports on the modeling and optimization of the electrospinning process of gelatin/chitosan, using response surface methodology. The individual and the interaction effects of the gelatin/chitosan blend ratio (50/50, 60/40 and 70/30), applied voltage (20, 25 and 30 kV) and feeding rate (0.2, 0.4 and 0.6 mL h^?1) on the mean fiber diameter and standard deviation of the fiber diameter were investigated on optimization section, using scanning electron microscopy. To fabricate the nanofibrous gelatin/chitosan blend, trifluoroacetic acid/dichloromethane was selected as the solvent system. The model obtained for the mean fiber diameter has a quadratic relationship with applied voltage and feeding rate. The interaction between applied voltage and flow rate were found significant but the interactions of blend ratio and flow rate and also blend ratio and applied voltage were negligible. A quadratic relationship was obtained for applied voltage and flow rate with standard deviation of the fiber diameter and there was no interaction between the parameters in the model. The optimum condition for electrospinning of gelatin/chitosan was also introduced using the model obtained in this study. Scanning electron micrographs of human dermal fibroblast cells on the nanofibrous structures show good attachment and proliferation on the fabricated scaffold surface. Electrospun gelatin/chitosan nanofibrous mats have great potential for use as a scaffold for skin tissue engineering. © 2014 Society of Chemical Industry     

Long time release of water soluble drug from hydrophilic nanofibrous material

In this study, mesoporous silica nanoparticles (MSNs) were embedded into the hydrophilic poly(vinyl alcohol) (PVA) nanofibrous mats to achieve sustained release of water soluble drug from hydrophilic nanofibrous mats. MSNs were successfully prepared based on a sol–gel method. Water soluble drug naproxen sodium was then loaded into the mesopores of the MSNs, and different amounts of the drug-loaded MSNs were further incorporated into the fibers by the electrospinning process. Morphology of the nanofibrous mats was investigated, and it was found that all the fibers exhibited fibrous structure. Interestingly, lots of protrusions could be observed from the scanning electron microscopy images with high magnification, and numbers of the protrusions increased with the increasing of loading ratios of the MSNs from 5 to 15%. In addition, the wetting behaviors of the nanofibrous mats were also measured, and the water contact angles of all the mats were measured to be 0°. Finally, the drug release results indicated that all the PVA/MSNs composite nanofibrous mats showed an obviously prolonged drug release. The optimal loading ratio of the MSNs in the nanofibers was 10% due to the slowest drug release rate. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47922.     

Electrospinning of antibacterial poly(vinylidene fluoride) nanofibers containing silver nanoparticles

Poly(vinylidene fluoride) (PVDF) nanofibrous mats containing silver nanoparticles were prepared by electrospinning. The diameter of the nanofibers ranged between 100 and 300 nm, as revealed by scanning electron microscopy. The silver nanoparticles were dispersed, but some aggregation was observed with transmission electron microscopy. The content of silver nanoparticles incorporated into the PVDF nanofibrous mats was determined by inductively coupled plasma and X‐ray photoelectron spectroscopy. The antibacterial activities of the samples were evaluated with the colony‐counting method against Staphylococcus aureus (Gram‐positive) and Klebsiella pneumoniae (Gram‐negative) bacteria. The results indicate that the PVDF nanofibrous mats containing silver nanoparticles showed good antibacterial activity compared to the PVDF nanofiber control. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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     

Antibacterial ciprofloxacin HCl incorporated polyurethane composite nanofibers via electrospinning for biomedical applications

We report on the preparation and characterization of polyurethane (PU) composite nanofibers by electrospinning. Two different approaches were adopted to obtain the PU composite nanofibers. In the first approach, a homogeneous solution of 10 wt% PU containing ciprofloxacin HCl (CipHCl) drug was electrospun to obtain PU/Drug composite nanofibers. And in the second approach, the PU with ciprofloxacin HCl drug and ceramic hydroxyapatite (HA) particles were electrospun to obtain the PU/Drug and PU/Drug/HA composite nanofibers. The surface morphology, structure, bonding configuration, optical and thermal properties of the resultant products were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and UV–vis spectroscopy. The antibacterial activity was tested against common food borne pathogenic bacteria, namely, Staphylococcus aureus, Escherichia coli by the minimum inhibitory concentration (MIC) method. Our result results demonstrate that these composite nanofibers possess superior characteristics which can utilized for variety of applications.     

Effects of fiber surface chemistry and roughness on interfacial structures of electrospun fiber reinforced epoxy composite films

This work reported the effect of surface chemistry and roughness of electrospun fibers on fiber/matrix interfacial structures and the resultant macroscopical properties of composite films. Three types of fibrous mats composed of ultrafine fibers, that is, cellulose acetate (CANM), polyurethane (PUNM), and cellulose acetate/polyurethane composite (CAPUNM) were fabricated through electrospinning. CA fiber surfaces were rough with many hydroxyl groups; PU fiber surfaces were smooth, whereas CAPU composite fibers exhibited cocontiuous structure with rough surfaces. The fiber‐reinforced epoxy composite films were prepared by the solution impregnation method. The fractured surfaces of the composites were analyzed by scanning electron microscopy. Severe interfacial debonding and fiber pullouts were observed for PUNM/epoxy composites, while strong interfacial adhesion was formed for CANM/epoxy and CAPUNM/epoxy composites. The interfacial structure played important roles in the visible light transmittance of the composite films. For example, CANM/epoxy films showed the best optical property, whereas PUNM/epoxy films displayed the poorest light transmitting property and were translucent. The interfacial structure also affected the mechanical properties of the composites. The mechanical strength of fibrous mats followed an increasing order of CANM < CAPUNM < PUNM, but the mechanical strength of the composite films was in a reverse order, that is, CANM/epoxy > CAPUNM/epoxy > PUNM/epoxy. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

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.     

The Influence of Pre‐Electrospinning Plasma Treatment on Physicochemical Characteristics of PLA Nanofibers

Morphology, crystallinity, thermal, and mechanical properties of nanofibrous mats are known to highly affect the behavior of these materials in desired applications. In this study, multiple characteristics of poly(lactic acid) (PLA) nanofibrous mats prepared from plasma‐treated pre‐electrospinning solutions are studied as a function of various plasma operational parameters. X‐ray diffraction, differential scanning calorimetry, thermogravimetric analysis, X‐ray photoelectron spectroscopy, scanning electron microscopy, and tensile tests are performed. In addition, the pristine and plasma‐treated PLA solutions are examined with size exclusion chromatography to study the effect of the conducted pre‐electrospinning plasma treatments (PEPT) on the molecular weight of PLA. Aging analysis of the pristine and plasma‐treated solutions is also performed by evaluating the viscosity, conductivity, surface tension, and pH during an aging period of 10 days. To investigate if the results are only affected by the plasma treatment or also affected by the electrospinning, pristine and plasma‐treated PLA cast layers are also analyzed. The results reveal that PEPT preserved the surface chemical composition of the nanofibers and the molecular weight distribution of PLA, while morphology and mechanical properties of the nanofibers are considerably enhanced. Moreover, plasma‐treated polymer solutions resulted in the formation of nicely elongated nanofibers up to 4 days after plasma treatment.