PVP/FF复合纳米纤维的制备与表征

采用静电纺丝技术制备了聚乙烯吡咯烷酮/二苯基丙氨酸(PVP/FF)复合纳米纤维;考察了FF含量、纺丝液流速对电纺纤维形貌及其平均直径的影响;利用扫描电镜对纤维表面形态进行了观察,通过X射线衍射和热重分析考察了纳米纤维中FF的存在状态及纳米纤维的热稳定性;通过全反射红外光谱分析了FF与PVP之间的相互作用。结果表明:当复合纤维中FF质量分数小于2%时,共混溶液的可纺性较好;复合纳米纤维直径随着FF含量的增大而先减小后增加,当FF的质量分数增加到5%时,复合纳米纤维的直径也相应增大;随着纺丝液流速的增大,复合纳米纤维的直径有逐渐增大的趋势,当纺丝液流速在0.2～0.6mL/h时,复合纳米纤维形貌较佳,纤维直径分布均匀,表面光滑无颗粒;PVP/FF复合纳米纤维中FF与PVP发生复合作用处于分散的无定形状态,分解温度范围变宽;FF与PVP之间具有良好的相容性。     

Effect of chitosan on morphology and conformation of electrospun silk fibroin nanofibers

The electrospinning of silk fibroin(SF)/chitosan(CS) blends with different composition ratios was performed with formic acid as a spinning solvent. The SF/CS blends containing up to the CS content of 30% could be electrospun into the continuous fibrous structure, although pure CS was not able to be electrospun into the fibrous structure. As-spun SF/CS blend nanofibers showed smaller diameter and narrower diameter distribution than pure SF nanofibers, and the diameter gradually decreased from 450 to 130 nm with the addition of CS in blends. However, at the blend compositions with above 40 wt% chitosan, the continuous SF nanofibers containing CS beads were produced. We also investigated the influence of the methanol treatment on the secondary structure of as-spun SF or SF/CS blend nanofibers by means of ATR-IR and solid-state CP-MAS ¹³C-NMR. Comparing with the pure SF nanofibers, the conformational change of the as-spun SF/CS blend nanofibers into β-sheet was faster because the CS with rigid backbone synergistically might promote the conformational transition of SF by an intermolecular interaction.     

Studies of electrospun regenerated SF/TSF nanofibers

The Bombyx mori silk fibroin/Tussah silk fibroin (SF/TSF) nanofibers with diameters between 300 and 3500 nm were prepared by electrospinning with the solvent HFIP. The average diameters of SF/TSF blend fibers increased from 404 to 1977 nm, with the increase of SF content in blend solutions, and the relationship between the average diameters of SF/TSF and SF content was proved to be linear correlation. Results from FTIR, TG-DTA and X-ray diffraction showed that the electrospun fibers were mainly β-sheet structure and, heterogeneous micro-structures. In particular, the presence of two different endothermic peaks at 300 and 360 °C in the TG-DTA curves may be ascribed to the thermal decomposition of SF and TSF. These results suggested that SF and TSF were still immiscible even dissolved in hexafluoroisopropanol (HFIP) after electrospinning and ethanol treatment. Moreover, the thermal decomposition temperature and enthalpy were improved with the blend of SF and TSF, else the SF/TSF nanofibers' moisture absorption was higher than the pure SF or TSF nanofibers. To study the cytocompatibility and cell behavior on the SF/TSF nanofibers, MSCs, VECs, and Neurons were seeded onto the nanofibers. Results indicated that the SF/TSF nanofibers promote cell attachment and spreading, suggesting that these nanofibers could be a candidate scaffold for blood vessel and nerve injury recovery.     

Preparation of chitosan bicomponent nanofibers filled with hydroxyapatite nanoparticles via electrospinning

Chitosan (CS) bicomponent nanofibers with an average diameter controlled from 100 to 50 nm were successfully prepared by electrospinning of CS and poly(vinyl alcohol) (PVA) blend solution. Finer fibers and more efficient fiber formations were observed with increased PVA contents. On this contribution, a uniform and ultrafine nanofibrous CS bicomponent mats filled with hydroxyapatite (HA) nanoparticles were successfully electrospun in a well devised condition. An increase in the contents of HA nanoparticles caused the conductivity of the blend solution to increase from 1.06 mS/cm (0 wt % HA) to 2.27 mS/cm (0.5 wt % HA), 2.35 mS/cm (1.0 wt % HA), respectively, and the average diameter of the composite fibers to decrease from 59 ± 10 nm(0 wt % HA) to 49 ± 10 nm (0.5 wt % HA), 46 ± 10 nm (1.0 wt % HA), respectively. SEM images showed that some particles had filled in the nanofibers whereas the others had dispersed on the surface of fibers, and EDXA results indicated that both the nanoparticles filled in the nanofibers and those adhered to the fibers were HA particles. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

柞蚕丝丝素/壳聚糖共混体系的静电纺丝研究

利用六氟异丙醇和三氟乙酸为溶剂,通过静电纺丝制备了不同共混比的柞蚕丝丝素(TSF)/壳聚糖(CS)纳米纤维。研究了TSF/CS共混比对纺丝液黏度、电导率和纤维形貌的影响。结果表明,TSF/CS共混液的电导率随CS含量的增加而增加;随着CS含量的增加(≤15%),共混液的黏度增加缓慢,纤维由转曲的扁平带状逐渐变为圆柱形且直径逐渐降低;当CS含量超过15%时,共混液的黏度随CS含量的增加而显著增大,纤维出现粗细两极分化现象。     

Co‐electrospun composite nanofibers of blends of poly[(amino acid ester)phosphazene] and gelatin

Electrospinning is known as a simple and effective fabrication method to produce polymeric nanofibers suitable for biomedical applications. Many synthesized and natural polymers have been electrospun and reported in the literature; however, there is little information on the electrospinning of poly[(amino acid ester)phosphazene] and its blends with gelatin. Composite nanofibers were made by co‐dissolving poly[(alaninoethyl ester)_0.67(glycinoethyl ester)_0.33phosphazene] (PAGP) and gelatin in trifluoroethanol and co‐electrospinning. The co‐electrospun composite nanofibers from different mixing ratios (0, 10, 30, 50, 70 and 90 wt%) of gelatin to PAGP consisted of nanoscale fibers with a mean diameter ranging from approximately 300 nm to 1 µm. An increase in gelatin in the solution resulted in an increase of average fiber diameter. Transmission electron microscopy and energy dispersive X‐ray spectrometry measurements showed that gelatin core/PAGP shell nanofibers were formed when the content of gelatin in the hybrid was below 50 wt%, but homogeneous PAGP/gelatin composite nanofibers were obtained as the mixing ratios of gelatin to PAGP were increased up to 70 and 90 wt%. The study suggests that the interaction between gelatin and PAGP could help to stabilize PAGP/gelatin composite fibrous membranes in aqueous medium and improve the hydrophilicity of pure PAGP nanofibers. Copyright © 2009 Society of Chemical Industry     

Fabrication and characterization of electrospun bionanocomposites of poly (vinyl alcohol)/nanohydroxyapatite/cellulose nanofibers

The aim of the present study was preparation, optimization, and systematic characterization of electrospun bionanocomposite fibers based on polyvinyl alcohol (PVA) as matrix and nanohydroxy apatite (nHAp) and cellulose nanofibers (CNF) as nanoreinforcements. The presence of nHAp and nHAp-CNF affected the morphology of electrospun mats and reduced fiber diameter, particularly at a higher content of nanofillers. The obtained results of FTIR, DSC, and WAXS proved the crystallinity reduction of electrospun nancomposites. Both nHAp and nHAp-CNF addition led to a significant increase of Young modulus with the highest stiffness for nanocomposite fibers at 10 wt% of nHAp and 3 wt% of CNF.     

Fabrication and characterization of chitosan/kefiran electrospun nanofibers for tissue engineering applications

Chitosan (CS)-based nanofibrous scaffolds are very promising in tissue engineering applications. However, electrospinning of CS is not possible unless using toxic solvents such as trifluoroacetic acid or by blending with other polymers. In the present study, we investigated CS-based nanofibers' fabrication by blending it with kefiran as a natural polysaccharide. A series of solutions with various CS to kefiran ratios were prepared and underwent electrospinning. The effects of main process parameters, including applied voltage and needle tip-to-collector distance on nanofibers' diameter and morphology, were also studied. Nanofibers containing 80% CS and 20% Kefiran with an average diameter of 81 ± 17 nm were successfully electrospun. Thermogravimetric analysis indicated the presence of both polymers in blend nanofibers. The diameter of CS/kefiran nanofibers increased with enhanced applied voltage, while needle tip-to-collector distance did not significantly affect the mean diameters. Appropriate viability of l929 cells on the obtained scaffolds was demonstrated utilizing Alamar blue assay. Also, cell attachment onto the fiber surface was confirmed by scanning electron microscopy. Results indicated that CS/kefiran nanofibrous scaffolds would be promising for tissue engineering applications.     

Electrospinning of polyacrylonitrile solutions containing diluted sodiumthiocyanate

The effect of NaSCN salt on the spinnability of polyacrylonitrile (PAN) solutions, its resulting morphology, mechanical property, and the flame resistance of the resulting electrospun nanofibers were studied. The intent was to develop a method to produce nanosized carbon fiber precursors with good properties. Electrospun PAN nanofibers from 9.7–9.9 wt% PAN/sodiumthiocyanate (NaSCN) (aq)/Dimethylformamide (DMF) solutions with 1.0–2.9 wt% NaSCN (aq), and 10–15 wt% PAN/DMF solutions without salt exhibited good spinnability and morphology with no beading in the range of applied voltage (18–20 kV) and take‐up velocity (9.8–12.3 m/s). The relatively high take‐up velocity produced good yarn alignment. The diameter distributions of the PAN nanofibers containing the NaSCN salt were narrower than those of the PAN/DMF nanofibers without the salt. It was determined that the maximum content of salt for production of electrospun PAN nanofibers with good morphology was below 3.8 wt% (40 wt% based on PAN). The salt concentration can positively influence on the narrow diameter distributions of the resulting electrospun fibers. Also, it could be confirmed that the salt effect on mechanical property and flame resistance of electrospun PAN nanofibers. In particular, the elongation of the PAN nanofiber with 2.9 wt% NaSCN (aq) was significantly increased as much as 186% compared with that of 10 wt% PAN nanofiber without the salt. The flame resistance and mechanical properties of the stabilized PAN nanofibers with NaSCN (aq) increased after oxidization process. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers.     

Composite chitosan/poly(ethylene oxide) electrospun nanofibrous mats as novel wound dressing matrixes for the controlled release of drugs

The aim of this study was to develop novel biomedical electrospun nanofiber mats for controlled drug release, in particular to release a drug directly to an injury site to accelerate wound healing. Here, nanofibers of chitosan (CS), poly(ethylene oxide) (PEO), and a 90 : 10 composite blend, loaded with a fluoroquinolone antibiotic, such as ciprofloxacin hydrochloride (CipHCl) or moxifloxacin hydrochloride (Moxi), were successfully prepared by an electrospinning technique. The morphology of the electrospun nanofibers was investigated by scanning electron microscopy. The functional groups of the electrospun nanofibers before and after crosslinking were characterized by Fourier transform infrared spectroscopy. X‐ray diffraction results indicated an amorphous distribution of the drug inside the nanofiber blend. In vitro drug‐release evaluations showed that the crosslinking could control the rate and period of drug release in wound‐healing applications. The inhibition of bacterial growth for both Escherichia coli and Staphylococcus aureus were achieved on the CipHCl‐ and Moxi‐loaded nanofibers. In addition, both types of CS/PEO and drug‐containing CS/PEO nanofibers showed excellent cytocompatibility in the cytotoxicity assays. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42060.     

Morphology,physical, and mechanical properties of potentially applicable coelectrospun polysulfone/chitosan-polyvinyl alcohol fibrous membranes in water purification

Polysulfone (PSU) is a widely used polymer in water purification membranes. However, its hydrophobicity hinders its practical application. Herein, the wettability of PSU has been improved by producing a coelectrospun fibrous composite membrane using a hydrophilic component, chitosan-polyvinyl alcohol (CS-PVA). First, different proportions of PVA and CS solutions were mixed and electrospun to prepare CS-PVA blend fibers. Scanning electron microscope (SEM) observations revealed that CS-PVA blend fibers with maximum CS content can be obtained in 30:70 CS:PVA weight ratio. The optimum CS-PVA solution was subsequently used alongside PSU solution and were fed into two distinct syringes, which were then electrospun simultaneously at a constant voltage and distance of 15 kV and 15 cm, respectively. Different composite compositions of PSU/CS-PVA were achieved using different feeding rates for each solution. Based on SEM images, the prepared composite fibers were beadless. The ultimate strength of the composite mats decreased by increasing the amount of CS-PVA due to the significant difference in the fiber diameter of each component and the resulting stress concentration. However, the thermal stability of composite membranes remained almost the same as pure PSU fibers. Moreover, samples with higher CS-PVA content showed better wettability and higher water flux.     

The morphology of electrospun polystyrene fibers

Electrospinning is a process of electrostatic fiber formation which uses electrical forces to produce polymer nanofibers from polymer solution. The electrospinning system consists of a syringe feeder system, a collector system, and a high power supplier. The important parameters in the morphology of electrospun polystyrene fibers are concentration, applied voltage, and solvent properties. Higher concentrations of the polymer solution form thicker fibers and fewer beads. When the concentration is 7 wt%, electrospun fibers have an average diameter of 340 nm, but as the concentration of PS increases to 17 wt%, the fiber diameter gradually thickens to 3,610 nm. The fiber morphology under different solvent mixture ratios and solvent mixtures has also been studied.     

Preparation of the chitosan containing nanofibers by electrospinning chitosan–gelatin complexes

Electrospinning is an interesting technique, which provides a facile and an effective mean in producing nonwoven fibrous materials; however, for producing nanofibers, investigation of the electrospinning conditions is very important. In this study, chitosan, gelatin, and their polyelectrolyte complexes (PECs) were electrospun to prepare nonwoven nanofibrous mats. The concentrations of chitosan and gelatin solutions and electric field (kV/cm) were optimized. The solutions were then blended in different ratios (0–100%) to get electrospun nanofibrous mats. Solution concentration and electric field showed pronounced effect on the electrospinnability and fiber diameter of these systems. Mostly large beads coexisted with the fibers were observed for chitosan at 1 wt% solution concentration, which then showed good electrospinnability at 2 wt% (nanofiber diameter was 145 and 122 nm at 15 and 20 kV/10 cm, respectively), whereas gelatin showed no electrospinnability below 15 wt% solution concentration and a homogenous fibers network at 15 wt% (149 nm at 20 kV/10 cm). The morphology and diameter of chitosan–gelatin PEC nanofibers varied with the chitosan/gelatin ratio. The crystallinity of chitosan was also observed to reduce with electrospinning and addition of gelatin. POLYM. ENG. SCI. 50:1887–1893, 2010. © 2010 Society of Plastics Engineers     

The influence of electrospinning parameters on the structural morphology and diameter of electrospun nanofibers

Electrospinning is a simple method of producing nanofibers by introducing electric field into the polymer solutions. We report an experimental investigation on the influence of processing parameters and solution properties on the structural morphology and average fiber diameter of electrospun poly ethylene oxide (PEO) polymer solution. Experimental trials have been conducted to investigate the effect of solution parameters, such as concentration, molecular weight, addition of polyelectrolyte in PEO solution, solvent effect, as well as governing parameter, such as applied voltage. The concentration of the aqueous PEO solution has shown noteworthy influence on the fiber diameter and structural morphology of electrospun nanofibers. At lower concentrations of PEO polymer solution, the fibers showed irregular morphology with large variations in fiber diameter, whereas at higher concentrations, the nanofibers with regular morphology and on average uniform fiber diameter were obtained. We find that the addition of polyelectrolytes, such as sodium salt of Poly acrylic acid (PAA) and Poly allylamine hydrochloride (PAH), increases the conductivity of PEO solutions and thereby decreases the bead formation in electrospun nanofibers. The increase in applied voltage has been found to affect the structural morphology of nanofiber while the addition of ethanol in PEO solution diminishes the bead defects. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Effects of halloysite nanotubes and kaolin loading on the tensile,swelling, and oxidative degradation properties of poly(vinyl alcohol)/chitosan blends

[Halloysite nanotubes (HNT)]‐filled and kaolin filled composite films based on poly(vinyl alcohol) (PVA)/chitosan (CS) blend were prepared via solution casting method. Tensile properties, fracture morphology, FTIR spectra, thermal stability, swelling properties, moisture absorption, and oxidative degradation of the composite films were investigated. Addition of 0.5 wt% of filler led to the optimum tensile properties of the films. Increased roughness and tearing in the fracture surface morphology supported the tensile results. The FTIR results indicated there were physical interactions present in the composite films. Thermal stability of the composite films differed slightly where PVA/CS/HNT composite films showed better thermal stability than PVA/CS/kaolin composite films. Moreover, the presence of HNT and kaolin fillers in the blend reduced the swelling and moisture absorption properties of the films. Finally, the composite films were degraded by using Fenton's reagent. Degradation percentage of the composite films decreased with increasing filler loading. J. VINYL ADDIT. TECHNOL., 19:55–64, 2013. © 2013 Society of Plastics Engineers     

Morphology of electrospun nylon‐6 nanofibers as a function of molecular weight and processing parameters

In the present study, the morphology and mechanical properties of nylon‐6 nanofibers were investigated as a function of molecular weight (30,000, 50,000, and 63,000 g/mol) and electrospinning process conditions (solution concentration, voltage, tip‐to‐collector distance, and flow rate). Scanning electron micrographs (SEM) of nylon‐6 nanofibers showed that the diameter of the electrospun fiber increased with increasing molecular weight and solution concentration. An increase in molecular weight increases the density of chain entanglements (in solution) at the same polymer concentration; hence, the minimum concentration to produce nanofibers was lower for the highest molecular weight nylon‐6. The morphology of electrospun fibers also depended on tip‐to‐collector distance and applied voltage concentration of polymer solution as observed from the SEM images. Trends in fiber diameter and diameter distribution are discussed for each processing variable. Mechanical properties of electrospun nonwoven mats showed an increase in tensile strength and modulus as a function of increasing molecular weight. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Preparation and characterization of biomimetic silk fibroin/chitosan composite nanofibers by electrospinning for osteoblasts culture

ABSTRACT: In this study, we have successfully fabricated electrospun bead-free silk fibroin [SF]/chitosan [CS] composite nanofibers [NFs] covering the whole range of CS content (0%, 25%, 50%, 75%, and 100%). SF/CS spinning solutions were prepared in a mixed solvent system of trifluoroacetic acid [TFA] and dichloromethane. The morphology of the NFs was observed by scanning electron microscope, and the average fiber diameter ranges from 215 to 478 nm. Confocal laser scanning microscopy confirms the uniform distribution of SF and CS within the composite NFs. To increase biocompatibility and preserve nanostructure when seeded with cells in culture medium, NFs were treated with an ethanol/ammonia aqueous solution to remove residual TFA and to change SF protein conformation. After the chemical treatment, SF/CS NFs could maintain the original structure for up to 54 days in culture medium. Properties of pristine and chemically treated SF/CS NFs were investigated by Fourier transform infrared spectroscopy [FT-IR], X-ray diffraction [XRD], and thermogravimetry/differential scanning calorimetry [TG/DSC]. Shift of absorption peaks in FT-IR spectra confirms the conformation change of SF from random coil to β-sheet by the action of ethanol, which is also consistent with the SF crystalline diffraction patterns measured by XRD. From TG/DSC analysis, the decomposition temperature peaks due to salt formation from TFA and protonated amines disappeared after chemical treatment, indicating complete removal of TFA by binding with ammonium ions during the treatment. This was also confirmed with the disappearance of F1s peak in X-ray photoelectron spectroscopy spectra and disappearance of TFA salt peaks in FT-IR spectra. The composite NFs could support the growth and osteogenic differentiation of human fetal osteoblastic [hFOB] cells, but each component in the composite NF shows distinct effect on cell behavior. SF promotes hFOB proliferation while CS enhances hFOB differentiation. The composite SF/CS NFs will be suitable for bone tissue engineering applications by choosing a suitable blend composition.PACS: 87.85.jf; 87.85.Rs; 68.37.Hk.     

Effect of blend composition on the morphology development of electrospun fibres based on PAN/PMMA blends

BACKGROUND: The aim of the work presented was to determine the morphology development and relevant change in fibre diameter of a binary polymer blend system during an electrospinning process. The size of the fibre diameter is one of the important factors determining the general properties of non‐woven mats formed from electrospun fibres. RESULTS: The morphology and diameter of electrospun polyacrylonitrile (PAN)/poly(methyl methacrylate) (PMMA) blends were investigated as a function of blend ratio using scanning electron microscopy. The diameter of the electrospun PAN/PMMA fibres decreased with increasing PMMA content up to 50 wt%, and then increased again with further increase of PMMA. After thermal treatment, the fibres shrank, and an irregularly shaped morphology was observed. CONCLUSION: The electrospinning of incompatible PAN/PMMA blends leads to a microphase‐separation morphology of fibres. A phase inversion occurs at a PMMA content of between 50 and 75 wt%. Due to the phase inversion, the fibre diameter shows a minimum value at the relevant composition. Copyright © 2008 Society of Chemical Industry     

Effect of solution properties on nanofibrous structure of electrospun poly(lactic‐co‐glycolic acid)

Electrospinning of poly(lactic‐co‐glycolic acid) (PLGA) in chloroform or 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) was investigated, focusing on its solution parameters, to develop nonwoven biodegradable nanofibrous structures for tissue engineering. PLGA nanofibers were obtained by electrospinning of 15 wt % PLGA solution and the resulting average fiber diameters were varied with the range of 270–760 nm, depending on solution property. When small amounts of benzyl triethylammonium chloride (BTEAC) was added to the PLGA/chloroform solution, the average diameter was decreased from 760 to 450 nm and the fibers were densely amounted in a straight shape. In addition, the average fiber diameter (270 nm) of nanofibers electrospun from polar HFIP solvent was much smaller than that (760 nm) of nanofibers electrospun from nonpolar chloroform solvent. Therefore, it could be concluded that conductivity or dielectric constant of the PLGA solution was a major parameter affecting the morphology and diameter of the electrospun PLGA fibers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1214–1221, 2006     

Effects of varying melt flow rates on laser melt-electrospinning of low-density polyethylene nanofibers

The ultimate functionality and applicability of polymeric nanofibers are mainly to subject on its diameter. This study explores the influence of melt flow rates (MFRs) of low-density polyethylene (LDPE) on the diameter of laser melt electrospun nanofibers. Ethylene-vinyl alcohol (EVOH) copolymer was added to the nonpolar LDPE as a spinning aid. After electrospinning, the EVOH was removed from LDPE/EVOH blend fiber by treating with isopropanol/water solution and LDPE nanofiber was obtained with a diameter of only 190 ± 85 nm for the highest MFR. A linear diameter reduction was observed for pure LDPE and EVOH removed LDPE fiber with the increase of MFR. However, a slight diameter increment was reported for the LDPE/EVOH blend fiber with higher MFR due to the improved melt viscosity of the component. A massive diameter decrement was found after EVOH removal from the blended fiber, resulting in the renovation of microfiber to a stable nanoscale dimension.