Cocontinuous cellulose acetate/polyurethane composite nanofiber fabricated through electrospinning

Cocontinuous cellulose acetate (CA)/polyurethane (PU) composite nanofibers were obtained through electrospinning of partially miscible CA and PU in 2:1 N,N‐dimethylacetamide (DMAc)/acetone mixture solvent. Their structures, mechanical, and thermal properties were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and differential scanning calorimetry (DSC). The structures and morphologies of the nanofibers were affected by component ratio in the binary mixtures. PU component not only facilitated the electrospinning of CA at CA concentration down to 12 wt%, but reinforced the tensile strength of CA/PU nanofibrous mats, while semirigid component CA in the composite nanofibers could greatly improve the rigidity and dimensional stability of CA/PU nanofibrous mats. In a series of nanofibrous mats with varied CA/PU composition ratios, CA/PU 20/80 showed excellent tensile strength and Young's modulus. The residual product after selective removal of any one of the components in CA/PU composite nanofibers by washing with proper solvent maintained the fiber structure but greatly reduced the fiber size, suggesting CA/PU composite fibers showed a cocontinuous nanofiber structure due to phase separation in the spinning solution and in the course of electrospinning. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers     

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     

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.     

Effect of air blowing on the morphology and nanofiber properties of blowing‐assisted electrospun polycarbonates

Polycarbonate (PC) nanofibers are prepared using the air blowing‐assisted electrospinning process. The effects of air blowing pressure and PC solution concentration on the physical properties of fibers and the filtration performance of the nanofiber web are investigated. The air blowing‐assisted electrospinning process produces fewer beads and smaller nanofiber diameters compared with those obtained without air blowing. Uniform PC nanofibers with an average fiber diameter of about 0.170 μm are obtained using an applied voltage of 40 kV, an air blowing pressure of 0.3 MPa, a PC solution concentration of 16%, and a tip‐to‐collection‐screen distance (TCD) of 25 cm. The filtration efficiency improvement of the air blowing‐assisted electrospun web can be attributed to the narrow distribution of fiber diameter and small mean flow pore size of the electrospun web. Performance results show that the air blowing‐assisted electrospinning process can be applied to produce PC nanofiber mats with high‐quality filtration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Thermal conductivities of electrospun polyimide‐mesophase pitch nanofibers and mats

In this article, we report the preparation and thermal properties of polyimide–mesophase pitch (MP) composite nanofibers and associated nanofiber nonwoven mats produced using an electrospinning process. The addition of MP increased the thermal conductivities of both the individual composite nanofibers and the in‐plane conductivities of the nanofiber mats. The out‐of‐plane conductivity of the mats remained relatively low due to low through thickness connectivity between the nanofibers. These nanofiber mats are flexible and very thin and are good candidates for thermal management films for future flexible electronic devices. POLYM. ENG. SCI., 54:977–983, 2014. © 2013 Society of Plastics Engineers     

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.     

Self synthesize of silver nanoparticles in/on polyurethane nanofibers: Nano‐biotechnological approach

In this study, we are introducing a new class of Polyurethane (PU) nanofibers containing silver nanoparticles (NPs) by electrospinning. A simple method not depending on the addition of foreign chemicals has been used to self‐synthesize of silver NPs in/on PU nanofibers. Typically, a sol?gel consisting of AgNO₃/PU/N,N‐dimethylformamide (DMF) has been electrospun and aged for a week, so silver NPs have been created in/on PU nanofibers. Syntheses of silver NPs were carried out by exploiting the reduction ability of the DMF solvent which is the main constituent to obtain PU electrospun nanofibers in decomposition of silver nitrate precursor into silver NPs. Physiochemical characterizations confirmed well oriented nanofibers and good dispersing of pure silver NPs. Various parameters affecting utilizing of the prepared nanofibers on various nano‐biotechnological fields have been studied. For instance, the obtained nanofiber mats were checked for mechanical properties which showed the improvement of the tensile strength upon increase in silver NPs content. Moreover, the nanofibers were subjected to 10 times successive washing experiments with using solid to liquid ratio of 3 : 5000 for 25 h, UV spectroscopy analysis reveals no losses of silver NPs from the PU nanofibers. 3T3‐L1 fibroblasts were cultured in presence of the designed nanofibers. The morphological features of the cells attached on nanofibers were examined by BIO‐SEM, which showed well attachment of cells to fibrous mats. The cytotoxicity results indicated absence of toxic effect on the 3T3‐L1 cells after cell culturing. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

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 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     

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.     

Structural characterization and dynamic water adsorption of electrospun polyamide6/montmorillonite nanofibers

A facile compounding process, which combined nanocomposite process with electrospinning for preparing novel polyamide6/organic modified montmorillonite (PA6/O‐MMT) composite nanofibers, is reported. In this compounding process, the O‐MMT slurry was blended into the formic acid solution of PA6 at moderate temperatures, where the nanosized O‐MMT particles were first dispersed in N,N‐dimethyl formamide solvent homogeneously via ultrasonic mixing. Subsequently the solution via electrospinning formed nanofibers, which were collected onto aluminum foil. The O‐MMT platelets were detected to be exfoliated at nanosize level and dispersed homogeneously along the axis of the nanofibers using an electron transmission microscope. Scanning electron microscope and atomic force microscope were used to analysis the size and surface morphology of polyamide6/O‐MMT composite nanofibers. The addition of O‐MMT reduced the surface tension and viscosity of the solution, leading to the decrease in the diameter of nanofiber and the formation of rough and ridge‐shape trails on the nanofiber surface. The behavior of the dynamic water adsorption of composite nanofibers was also investigated and discussed in this article. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Enhancing water swelling ability and mechanical properties of water‐swellable rubber by PAA/SBS nanofiber mats

Investigation of the potential use of nanofibers to reinforce composites has gained significance in many applications. In this article, the nanofiber mats of poly(acrylic acid) (PAA) and styrene–butadiene–styrene (SBS) triblock copolymer with composites structure were interweaved by double needle electrospinning process. The multiple nanofiber mats were added to conventional water‐swellable rubber (WSR). Improved mechanical and physical properties of WSR were obtained. Enhancement of the swellability of WSR + PAA/SBS nanofiber mats was derived from the PAA constituent absorbing water from the surface into the bulk and introducing random internal water channels between discontinuous superabsorbent polymers. The role of SBS nanofibers in the composite of WSR + PAA/SBS nanofiber mats was more related to the mechanical properties, where the breaking force of the composite increased to twice that of the conventional WSR. Interestingly, after immersion of the WSR + PAA/SBS nanofiber mats in water for 1 week, there was only a slight decrease in their mechanical properties of less than 5% compared to the dry state. The mechanisms and effects of the nanofiber mats in enhancing the mechanical and water swelling properties of WSR are also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44213.     

Preparation and characterization of ampicillin‐incorporated electrospun polyurethane scaffolds for wound healing and infection control

Electrospinning is a desired method to produce interconnected flexible nanofibrous structures suitable for tissue engineering, drug delivery, and wound healing. Ampicillin‐loaded polyurethane (PU) nanofiber mats were electrospun with the antibiotic dispersed in well‐oriented nanofibers. The identification of functional groups, molecular interactions and surface morphology of the fibers were analyzed using Infrared, Raman, ¹H NMR, SEM, and TEM. Weak interactions exist between the functional groups of ampicillin and PU in electrospun fibers at ratios 1:10, 1.5:10, and 2:10. The effect of β‐lactam antibiotic ampicillin on the characteristics of electrospun PU was studied using XRD, TGA, and DSC. Their antibacterial property is proved by good zone of inhibition against Staphylococcus aureus and Klebsiella pneumonia. Cytotoxicity tests on the electrospun scaffolds were performed with normal human keratinocyte cells (HaCaT cells). Results indicate that ampicillin‐incorporated PU scaffolds are well suited for applications in wound healing and infection control. POLYM. ENG. SCI., 55:541–548, 2015. © 2014 Society of Plastics Engineers     

Preparation and characterization of octadecane/polyurea nanocapsule‐embedded poly(ethylene oxide) nanofibers

This article describes the preparation and characterization of latent heat storage poly(ethylene oxide) nanofibers (LHS‐PEO nanofibers) with octadecane/polyurea (PCM/PU) nanocapsules. PCM/PU nanocapsules were prepared by interfacial polycondensation from toluene 2,4‐diisocyanate and ethylene diamine in a resin‐fortified emulsion system. LHS‐PEO nanofibers were prepared using an electrospinning procedure with varying PCM/PU nanocapsules content, i.e., from 0 to 8 wt %. The PCM/PU nanocapsules were polydisperse with an average diameter of 200 nm. The melting and freezing temperatures were determined as 23.7 and 28.2°C, respectively, and the corresponding latent heats were determined as 123.4 and 124.1 kJ kg^?1, respectively. The encapsulation efficiency of the PCM/PU nanocapsules was 78.1%. The latent heat capacity of the LHS‐PEO nanofibers increased as the PCM/PU nanocapsules content increased. Defects, such as holes and disconnection of the nanofibers, were observed, particularly inside the LHS‐PEO nanofibers. For packaging applications, mats were fabricated from the nanocapsules‐embedded nanofibers with varying nanocapsule content and the mats’ surface temperatures were monitored with a thermal imaging camera. The results proved the feasibility of using the LHS‐PEO nanofibers for thermal energy storage and functional packaging materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42539.     

Magnetic‐field‐assisted electrospinning highly aligned composite nanofibers containing well‐aligned multiwalled carbon nanotubes

Composite nanofiber meshes of well‐aligned polyacrylonitrile (PAN)/polyvinylpyrrolidone (PVP) nanofibers containing multiwalled carbon nanotubes (MWCNTs) were successfully fabricated by a magnetic‐field‐assisted electrospinning (MFAES) technology, which was confirmed to be a favorable method for preparation of aligned composite nanofibers in this article. The MFAES experiments showed that the diameters of composite nanofibers decreased first and then increased with the increase of voltage and MWCNTs content. With the increase of voltage, the degree of alignment of the composite nanofibers decreased, whereas it increased with increasing MWCNTs concentration. Transmission electron microscopy observation showed that MWCNTs were parallel and oriented along the axes of the nanofibers under the low concentration. A maximum enhancement of 178% in tensile strength was manifested by adding 2 wt % MWCNTs in well‐aligned composite nanofibers. In addition, the storage modulus of PAN/PVP/MWCNTs composite nanofibers was significantly higher than that of the PAN/PVP nanofibers. Besides, due to the highly ordered alignment structure, the composite nanofiber meshes showed large anisotropic surface resistance, that is, the surface resistance of the composite nanofiber films along the fiber axis was about 10 times smaller than that perpendicular to the axis direction. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41995.     

Preparation and antibacterial activity of PET/chitosan nanofibrous mats using an electrospinning technique

The nanofiber deposition method, by electrospinning, was employed to introduce antibacterial activity and biocompatibility to the surface of poly (ethylene terephthalate) (PET) textiles. The polymer blends of PET and chitosan were electrospun on to the PET micro‐nonwoven mats for biomedical applications. The PET/chitosan nanofibers were evenly deposited on to the surface, and the diameter of the nanofibers was in the range between 500 and 800 nm. The surface of the nanofibers was characterized using SEM, ESCA, AFM, and ATR‐FTIR. The wettability of the PET nanofibers was significantly enhanced by the incorporation of chitosan. The antibacterial activity of the samples was evaluated utilizing the colony counting method against Staphylococcus aureus and Klebsiella pneumoniae. The results indicated that the PET/chitosan nanofiber mats showed a significantly higher growth inhibition rate compared with the PET nanofiber control. In addition, the fibroblast cells adhered better to the PET/chitosan nanofibers than to the PET nanofibers mats, suggesting better tissue compatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Anion conductive polymer nanofiber composite membrane: effects of nanofibers on polymer electrolyte characteristics

Polymer composite membranes composed of anion conductive polymer nanofiber mats and the corresponding polymer matrix were prepared and characterized for future alkaline fuel cells. In this paper, electrospinning was attempted to fabricate anion conductive nanofiber mats. The anion conductivity of the composite membrane was higher than the corresponding membrane without nanofibers under all conditions due to outstanding anion conductive characteristics of the nanofibers. In addition, because of the rigid and anisotropic structure of the nanofibers, membrane stabilities such as reductive degradation resistance and mechanical strength were very much improved. The gas permeability and excessive hydration swelling that will degrade fuel cells after long‐term operation were suppressed in the nanofiber composite membrane. These results indicated that excellent properties of the anion conductive nanofibers were demonstrated even in the composite membrane, leading to the potential application of anion conductive nanofibers in future fuel cells. © 2016 Society of Chemical Industry     

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.     

Optimization of biodegradable PEG/PLGA nanofiber mats electrospinning process for anti‐adhesion application

Electrospinning is a direct, continuous, and useful technique to prepare nanofiber by applying electrostatic forces. In this study, poly(lactic‐co‐glycolic acid)/poly(ethylene glycol) (PLGA/PEG) nanofiber mats were prepared, and electrospinning process was optimized to obtain appropriate fiber diameter and hydrophilicity for anti‐adhesion application. Optimization of applied voltage, PEG content, and feeding rate was investigated using response surface methodology. A total of 15 trials were designed to optimize the parameters. Fiber diameter was measured using scanning electron microscopy. Individual and interactive effects of the solution properties were determined. Moreover, the adequacy of the models was verified by validation experiments. For anti‐adhesion test, a nanofiber mat was produced based on the suggested optimum electrospinning conditions. Results showed that optimum fiber diameters were obtained using 7.5% PEG content, applied voltage of 19 kV, and flow rate of 3 mL/h. Experimental results were in good agreement with the predicted fiber diameters. Furthermore, a rat model of sidewall defect‐cecum abrasion was employed to investigate the efficacy of PEG/PLGA in preventing postoperative peritoneal adhesions. Hence, this study provides an overview on the fabrication of PLGA/PEG nanofibers with targeted diameter, which may be used in anti‐adhesion. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46282.     

Characterization and cell response of electrospun Rana chensinensis skin collagen/poly(l‐lactide) scaffolds with different fiber orientations

Collagen was extracted from Rana chensinensis skin supplied from byproducts via an acid enzymatic extraction method. The R. chensinensis skin collagen (RCSC) and poly(l ‐lactide) (PLLA) were blended at a 3:7 ratio in 1,1,1,3,3,3‐hexafluoroisopropanol (HFIP) at a concentration of 10% (g/mL) and electrospun to produce nanofibers in an aligned and random orientation. For comparison, pure PLLA nanofibrous membranes with aligned and random nanofiber orientations were also produced. The secondary structure of the RCSC nanofibers was investigated by circular dichroism to confirm that the extracted substance was collagen. The presence of collagen in the blend nanofiber was verified by LSCM. The blended nanofibers showed uniform, smooth, and bead‐free morphologies and presented a smaller fiber diameter (278 and and 259 nm) than the pure the ones of PLLA (559 and and 439 nm) nanofibers. It was found that the addition of RCSC and the modification of the nanofiber's orientation affected the fiber's diameter and the crystallization of PLLA. The cell viability studies with human fibroblast cells demonstrated that the RCSC/PLLA nanofibrous membranes formed by electrospinning exhibited good biocompatibility and that the aligned scaffolds could regulate the cell morphology by inducing cell orientation. The empirical results in this study indicated that the aligned RCSC/PLLA nanofibrous membrane is a potential wound dressing candidate for skin regeneration. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45109.