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     

Blood compatibility and physicochemical assessment of novel nanocomposite comprising polyurethane and dietary carotino oil for cardiac tissue engineering applications

Cardiovascular diseases (CVD) were estimated to claim 17 million lives each year. Among these, coronary heart disease almost accounts 50% deaths associated with CVD, which causes the blockage of the coronary arteries that supplies blood to the heart. Nowadays, the cardiac tissue engineering have become a promising solution to overcome the drawbacks associated with current therapies. Further, the scaffold used in cardiac tissue engineering must possess thromboresistant and anticoagulant nature to serve as a plausible candidate for cardiovascular applications. In this present investigation, a novel nanocomposite based on polyurethane (PU) and carotino oil was fabricated using electrospinning. Scanning electron microscopy images indicated that the nanocomposites have smaller fiber diameter (702 ± 130 nm) compared to the pristine PU (969 ± 217 nm). The Fourier transform infrared spectroscopy analysis confirmed the interaction between the carotino oil and PU by the formation of hydrogen bond and shifting of CH peak. The contact angle of electrospun PU/carotino oil was found to be 119°, which was increased compared to pristine PU (86°) indicating the hydrophobic nature of developed nanocomposites. Moreover, the surface roughness and thermal stability were found to be enhanced due to the presence of carotino oil in the PU matrix indicated in atomic force microscopy and thermogravimetric analysis. The enhanced surface roughness of nanocomposites resulted in delayed activation of the blood clot as revealed in activated partial thromboplastin time and prothrombin time assay. Moreover, the hemolytic index of fabricated nanocomposites was found to very low of about 1.33% compared to pristine PU (2.73%), suggesting non‐hemolytic nature and also better blood compatibility. So, the developed PU/carotino nanocomposites having desirable characteristics like better physicochemical and blood compatibility may render appropriate potentials for raw materials of cardiac tissue engineering. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45691.     

Single-stage synthesis of electrospun polyurethane scaffold impregnated with zinc nitrate nanofibers for wound healing applications

In this study, a wound dressing scaffold was developed based on polyurethane (PU, 9 wt %) incorporated with zinc nitrate nanofibers (9 wt %) using an electrospinning technique. The morphological studies revealed that the electrospun nanocomposites showed smaller fiber (568 ± 136.69 nm) and pore diameters (703 ± 60.76 nm) than the pure PU (fiber diameter 1159 ± 147.48 nm and pore diameter 1087 ± 62.51 nm). Energy-dispersive X-ray spectroscopy confirmed the presence of zinc nitrate in the PU matrix. The formation of hydrogen bonds and the enhanced weight residue found by Fourier transform infrared spectroscopy and thermogravimetric analysis revealed the interaction of PU with zinc nitrate. Moreover, the contact angle measurements revealed the hydrophilic nature of the electrospun nanocomposite (84° ± 4.041°) compared to the control (100° ± 0.5774°). Mechanical testing and atomic force microscopy showed an improvement in the tensile strength (15.98 MPa) and surface roughness (277 nm) of the fabricated nanocomposites compared to the PU membrane (tensile strength 7.12 MPa and surface roughness 216 nm). Further, incorporation of zinc nitrate into PU improved the blood compatibility, as demonstrated by the prolonged blood clotting time (APTT 188 ± 4 s and PT 102.7 ± 3.786 s) compared to the pure PU (APTT 147.7 ± 3.512 s and PT 84.67 ± 2.517 s), as revealed in coagulation assays. Moreover, the electrospun nanocomposites showed a low hemolytic index and enhanced fibroblast proliferation rates, as indicated in the hemolysis and cytocompatibility studies. The newly developed wound dressing displayed better physicochemical characteristics, prolonged blood clotting time, and enhanced fibroblast proliferation rates, indicating that it might be utilized as an alternate candidate for wound dressings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 46942.     

原位热溶剂法制备ZnO纳米晶/PU复合纳米纤维及其吸附性能研究

通过静电纺丝法制备了直径为(320±51)nm的前驱体醋酸锌/聚氨酯(Zn(OAc)2/PU)复合纳米纤维。将前驱体先后经过0.1 mol/L NaOH乙醇溶液和甘油浴热处理,得到ZnO纳米晶/PU复合纳米纤维。讨论了甘油浴温度和时间对纳米纤维结构和形貌的影响,研究了其吸附性能。实验结果表明,经过0.1 mol/L NaOH乙醇溶液处理后,前驱体纤维Zn(OAc)2/PU转变为ZnO/PU纤维且ZnO主要以低结晶和无定型态存在;再经过甘油浴处理后,低结晶和无定型态的ZnO转变为晶型完整的六方晶系纤锌矿结构,得到了ZnO纳米晶/PU复合纳米纤维,该纤维对有机染料分子罗丹明B有良好的吸附性能。     

Photocatalytic degradation of dairy effluent using AgTiO2 nanostructures/polyurethane nanofiber membrane

Dairy effluent (DE) is environmentally toxic and needs special attention. Photocatalytic degradation of DE was studied using novel polyurethane (PU)-based membranes. Typically, silver–titanium dioxide nanofibers (AgTiO₂ NFs) and silver–titanium dioxide nanoparticles (AgTiO₂ NPs) were individually incorporated in PU electrospun nanofibers to overcome the mandatory sophisticated separation of the nanocatalysts, which can create a secondary pollution, after the treatment process. These nanomembranes were characterized in SEM, TEM, XRD and UV studies. The polymeric electrospun nanofibers were smooth and continuous, with an average diameter of about 550 nm, and held their nanofibrous morphology even after more than 2 h of photocatalytic degradation of DE, due to the good stability of PU in the aqueous solutions, which indicates good imprisoning of the functional photocatalysts. The PU–AgTiO₂ NPs and PU–AgTiO₂ NFs were effective materials for degradation of DE, even after two successive cycles. PU–AgTiO₂ NPs and PU–AgTiO₂ NFs showed a maximum degradation of 75% and 95%, respectively after 2 h. The significant enhancement of degradation in the PU–Ag–TiO₂ NPs and PU–Ag–TiO₂ NFs is attributed to the photoactivity of Ag–TiO₂ material under visible light irradiation.     

Study on microstructure and mechanical properties of polydiacetylene composite biosensors

10,12-Pentacosadiynoic acid (PCDA) monomers were mixed with polyurethane (PU) or poly(ethylene oxide) (PEO) and the mixtures were electrospun to obtain composite nanofibers that were then photopolymerized via ultraviolet radiation, resulting polydiacetylene (PDA) in the nanofibers. The PDA demonstrated color-changing properties in the presence of Escherichia coli, which exhibited potential for developing flexible colorimetric biosensors for medical textiles. Phase separation was found in the PEO–PDA fibers, resulting in amorphous PEO accumulation at the fiber surface. In contrast, the PU–PDA fibers demonstrated a homogeneous microstructure throughout the fibers. Tensile test results suggested a molecular orientation in the PU–PDA fibers that significantly improved the mechanical properties of the fibers. The presence of PDA in the matrix polymer reduced the overall strength and breaking elongation of both composite nanofibers in comparison to 100% PEO and PU fibers. A single PU–PDA fiber showed significantly higher stiffness and modulus than a single PEO–PDA fiber. Force–distance curve analysis suggested that the PU–PDA fibers exhibited an elastic deformation. In a comparison, the PEO–PDA fibers were brittle and showed low modulus. The results of structural and mechanical properties suggest that the PU–PDA nanofibers are a promising composite for developing nonadherent, durable, and flexible colorimetric biosensors used in medical textiles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47877.     

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.     

Fabrication and characterisation of nanofibrous polyurethane scaffold incorporated with corn and neem oil using single stage electrospinning technique for bone tissue engineering applications

In bone tissue engineering, the design of scaffolds with ECM is still challenging now-a-days. The objective of the study to develop an electrospun scaffold based on polyurethane (PU) blended with corn oil and neem oil. The electrospun nanocomposites were characterized through scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), contact angle measurement, atomic force microscopy (AFM) and tensile strength. The assays activated prothrombin time (APTT), partial thromboplastin time (PT) and hemolysis assay were performed to determine the blood compatibility parameters of the electrospun PU and their blends of corn oil and neem oil. Further, the cytocompatibility studies were performed using HDF cells to evaluate their proliferation rates in the electrospun PU and their blends. The morphology of the electrospun PU blends showed that the addition of corn oil and corn/neem oil resulted in reduced fiber diameter of about 845?±?117.86?nm and 735?±?126.49 nm compared to control (890?±?116.911?nm). The FTIR confirmed the presence of corn oil and neem oil in PU matrix through hydrogen bond formation. The PU blended with corn oil showed hydrophobic (112°?±?1) while the PU together with corn/neem oil was observed to hydrophilic (64°?±?1.732) as indicated in the measurements of contact angle. The thermal behavior of prepared PU/corn oil and PU/corn/neem oil nanocomposites were enhanced and their surface roughness were decreased compared to control as revealed in the AFM analysis. The mechanical analysis indicated the enhanced tensile strength of the developed nanocomposites (PU/corn oil - 11.88 MPa and PU/corn/neem oil - 12. 96 MPa) than the pristine PU (7.12 MPa). Further, the blood compatibility assessments revealed that the developed nanocomposites possess enhanced anticoagulant nature compared to the polyurethane. Moreover, the developed nanocomposites was non-toxic to red blood cells (RBC) and human fibroblast cells (HDF) cells as shown in the hemolytic assay and cytocompatibility studies. Finally, this study concluded that the newly developed nanocomposites with better physio-chemical characteristics and biological properties enabled them as potential candidate for bone tissue engineering.     

Bimetallic Zn/Ag doped polyurethane spider net composite nanofibers: A novel multipurpose electrospun mat

The objective of this study was to develop a new class of bimetallic ZnO/Ag embedded polyurethane multi-functional nanocomposite by a straightforward approach. Bimetallic nanomaterials, composed of two unlike metal elements, are of greater interest than the monometallic materials because of their improved characteristics. In the present study the bimetallic composite was prepared using sol–gel via the facile electrospinning technique. The utilized sol–gel was composed of zinc oxide, silver and poly(urethane). The physicochemical properties of as-spun composite mats were determined by X-ray diffraction pattern, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and transmission electron microscopy. The antibacterial activity was tested using Escherichia coli as model organism. The antibacterial test showed that ZnO:Ag/polyurethane composite possesses superior antimicrobial activity than pristine PU and ZnO/PU hybrids. Furthermore, our results illustrate that the synergistic effect of ZnO and Ag resulted in the advanced antimicrobial action of bimetallic ZnO/Ag composite mat. The viability and proliferation properties of NIH 3T3 mouse fibroblast cells on the ZnO:Ag/polyurethane composite nanofibers were analyzed by in vitro cell compatibility test. Our results indicated the non-cytotoxic behavior of bimetallic ZnO:Ag/polyurethane nanofibers towards the fibroblast cell culture. In summary, novel ZnO:Ag/polyurethane composite nanofibers which possess large surface to volume ratio with excellent antimicrobial activity were fabricated. The unique combination of ZnO and Ag nanoparticles displayed potent bactericidal effect due to a synergism. Hence the electrospun bimetallic composite indicates the huge potential in water filtration, clinical and biomedical applications.     

Preparation and characterization of wollastonite/titanium oxide nanofiber bioceramic composite as a future implant material

In this study, novel composites consisting of electrospun titanium dioxide (TiO₂) nanofibers incorporated into high-purity wollastonite glass ceramics were prepared as materials for use in hard tissue engineering applications. These materials were characterized and investigated by means of physical, mechanical and in vitro studies. The proposed composite showed greater densification and better mechanical characteristics compared to pure wollastonite. The influence of densification temperature and TiO₂ content was investigated. Typically, TiO₂/wollastonite composites having 0, 10, 20 and 30 wt% metal oxide nanofibers were sintered at 900, 1100 and 1250 °C. The results indicated that increasing TiO₂ nanofibers content leads to increase the bulk density, compressive strength and microhardness with negligible, high and moderate influence for the densification temperature, respectively. While porosity and water adsorption capacity decreased with increasing the metal oxide nanofibers with a considerable impact for the sintering temperature in both properties. Moreover, bone-like apatite formed on the surface of wollastonite and wollastonite/TiO₂ nanofibers soaked in simulated body fluid (SBF). All these results show that the inclusion of TiO₂ nanofibers improved the characteristics of wollastonite while preserving its in vitro bioactivity; hence, the proposed composite may be used as a bone substitute in high load bearing sites.     

Fabrication and Antibacterial Activity of Electrospun Nylon 6 Nanofibers Grafted With 2-Substituted Vinylimidazoles

The authors present the fabrication of electrospun nanofibers with antimicrobial properties by the UV-initiated grafting (photo-grafting) of 2-substituted vinylimidazoles onto nylon 6 nanofibers. The characterization was performed using IR spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM-EDX). The antimicrobial properties of the grafted electrospun nylon 6 nanofibers were evaluated against Escherichia coli and Staphylococcus aureus as model challenge microorganisms, using the dynamic shake flask method. All the grafted electrospun nylon 6 nanofibers exhibited excellent growth reduction of E. coli (99.94–99.99%) and S. aureus (99.55–99.99%). The electrospun nylon 6 nanofiber composites could be used twice before a decrease in antibacterial activity was observed. The study showed that electrospun nylon 6 nanofiber composites possess a potential for use to control pathogens in water.     

Osteocompatibility characterization of polyacrylonitrile carbon nanofibers containing bioactive glass nanoparticles

A kind of composite carbon nanofibers (CNF) containing bioactive glass (BG) nanoparticles was produced for bone regeneration by a combination of electrospinning and sol–gel techniques. To produce the BG, compounds such as calcium nitrate, triethyl phosphate and tetraethyl orthosilicate were used as precursors and hydrolyzed to form a sol–gel solution, which was then added to a polyacrylonitrile (PAN) solution in N,N-dimethylformamide. The resulting mixture was electrospun to form PAN nanofibers containing the BG precursors. Upon oxidation and carbonization, the PAN nanofibers and BG precursors transformed into continuous CNF embedded with BG nanoparticles (CNF/BG). Through this fabrication technique, several CNF/BG composites were obtained by controlling the feeding ratios of the different precursors giving rise to BG nanoparticles with various compositions (i.e. containing 70–90 mol% of SiO₂ component). In vitro biomineralization in a simulated body fluid and co-culture with MC3T3-E1 osteoblasts studies were performed to evaluate the osteocompatibility of the CNF/BG nanoparticle composites. When compared to pure CNF, the CNF/BG composites showed an improved ability to promote the in vitro formation of apatite and MC3T3-E1 proliferation, which was found to be dependent upon the composition of BG nanoparticles.     

Preparation and viscoelasticity of anisotropic polyurethane composites filled with TiO2 particles

An anisotropic structure arranged by fillers is an effective method to make composites possess special properties, but the conventional particle-reinforced polyurethane (PU) composites usually have an isotropic 0-3 structure. In this study, a precipitation method was used to synthesize TiO₂ particles. The particles were dispersed in a PU matrix, and the structures were observed by scanning electron microscopy. The results indicate that in the presence of an applied electric field, 1-3-like composites with TiO₂ particles in an oriented arrangement were prepared, while 0-3 PU composites were prepared without an electric field. Dynamic viscoelasticity test results show that the PU-TiO₂ composites with a 1-3-like structure have a higher storage and loss modulus. The creep properties of these two kinds of PU composites were measured and further fitted with a Findley power law and Weibull model. It was found that the creep resistance and recovery properties of the PU composites were enhanced by the anisotropic structures of the filler particles in the matrix. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47450.     

In situ Polymerization of Multi-Walled Carbon Nanotube/Nylon-6 Nanocomposites and Their Electrospun Nanofibers

Multiwalled carbon nanotube/nylon-6 nanocomposites (MWNT/nylon-6) were prepared by in situ polymerization, whereby functionalized MWNTs (F-MWNTs) and pristine MWNTs (P-MWNTs) were used as reinforcing materials. The F-MWNTs were functionalized by Friedel-Crafts acylation, which introduced aromatic amine (COC₆H₄-NH₂) groups onto the side wall. Scanning electron microscopy (SEM) images obtained from the fractured surfaces of the nanocomposites showed that the F-MWNTs in the nylon-6 matrix were well dispersed as compared to those of the P-MWNTs. Both nanocomposites could be electrospun into nanofibers in which the MWNTs were embedded and oriented along the nanofiber axis, as confirmed by transmission electron microscopy. The specific strength and modulus of the MWNTs-reinforced nanofibers increased as compared to those of the neat nylon-6 nanofibers. The crystal structure of the nylon-6 in the MWNT/nylon-6 nanofibers was mostly γ-phase, although that of the MWNT/nylon-6 films, which were prepared by hot-pressing the pellets between two aluminum plates and then quenching them in icy water, was mostly α-phase, indicating that the shear force during electrospinning might favor the γ-phase, similarly to the conventional fiber spinning.     

Morphology enhancement of TiO2/PVP composite nanofibers based on solution viscosity and processing parameters of electrospinning method

In this work, different sol solutions with various titanium tetraisopropoxide (TIP)/glacial acetic acid ratios in 2‐propanol with 5 wt % poly(vinyl pyrrolidone) (PVP) (M_w = 360,000 g/mol) were prepared and electrospun. Composition of the prepared sols and as‐spun TiO₂/PVP nanofibers were determined by Fourier transform infrared and Raman spectroscopy methods. Morphology of the electrospun TiO₂/PVP nanofibers was studied by scanning electron microscopy and transmission electron microscopy (TEM) techniques. Rheometry measurements of the sol solutions showed decrease of viscosity upon the addition of TIP to the polymer solutions with constant polymer and acid concentrations. The sol solution having the lowest viscosity (at shear rate 10 s^?1) but the highest TIP/glacial acetic acid ratio showed beaded nanofibers morphology when electrospun under 10 and 12 kV applied voltage while injection rate, needle tip to collector distance, and needle gauge were kept constant. However, smooth electrospun TiO₂/PVP composite nanofibers with the average nanofibers diameters (148 ± 79 nm) were achieved under the same condition when applied voltage increased to 15 kV. TEM micrographs of the electrospun TiO₂/PVP nanofiber showed that the TiO₂ particles with continuous structure are formed at the middle of the nanofiber and distributed along its axis. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46337.     

A study on high-performance poly(azo-pyridine-benzophenone-imide) nanocomposites via self-reinforcement of electrospun nanofibers

In this study, initially high molecular weight poly(azo-pyridine-benzophenone-imide) (PAPBI) has been fabricated using facile approach. Uniformly aligned electrospun PAPBI and PAPBI/multi-walled carbon nanotube (MWCNT) nanofibers were then produced via electrospinning of desired solutions. Self-reinforcement technique was used to fabricate PAPBI-based nanofiber reinforced films. Uniform dispersion, orientation and adhesion between carbon nanotubes and polymer improved the physical properties of resulting nanocomposites. Fourier transform infrared spectroscopy was used to identify the structures of polymer and self-reinforced nanocomposite films. Scanning and transmission electron microscopy showed that the electrospun PAPBI/MWCNT nanofibers were uniformly aligned and free of defects. Moreover, polyimide matrix was evenly coated on the surface of electrospun nanofibers, thus, preventing the fibers from bundling together. Samples of 1–3 wt% of as-prepared electrospun nanofibers were self-reinforced to enhance the tensile strength of the films. Films of 3 wt% PAPBI/MWCNT nanofiber-based nanocomposite showed higher value in tensile strength (417 MPa) relative to 3 wt% PAPBI nanofibers (361 MPa) reinforced film. Tensile modulus of the PAPBI/MWCNT system was also significantly improved (19.9–22.1 GPa) compared with PAPBI system (13.9–16.2 GPa). Thermal stability of PAPBI/MWCNT nanofibers reinforced polyimide was also superior having 10 % gravimetric loss at 600–634 °C and glass transition temperature 272–292 °C relative to the neat polymer (T ₁₀ 545 °C, T _g 262 °C) and PAPBI nanofiber-based system (T ₁₀ 559–578 °C, T _g 264–269 °C). New high-performance self-reinforced polyimide nanocomposites may act as potential contenders for light-weight aerospace materials.     

Thermal stability and thermal oxidation kinetics of PU/CA-MMT composites

In this work, we prepared three composites polyurethane (PU)/chlorhexidine acetate (CA), PU/montmorillonite (MMT), and PU/CA-MMT, and investigated their kinetics of thermal degradation at different heating rates at atmosphere. These materials had good thermal stability and aging resistance. The thermal stability of PU/CA (T_onset: 237.3°C) was not obviously enhanced by the addition of only CA when compared with that of PU (T_onset: 232.3°C), while the thermal stability of PU/MMT (T_onset: 273.4°C) was considerably enhanced by the addition of MMT due to the high thermal stability of MMT. CA-MMT filler was dispersed and exfoliated in PU more easily than CA or MMT in PU, so the composite PU/CA-MMT possessed the best thermal stability (T_onset: 285.8°C). In addition, PU/CA-MMT also had the best resistance to bacterial adhesion and antibacterial ability. The analysis with Flynn-Wall-Ozawa method showed that the activation energy of thermal oxidation of PU increased when CA-MMT was added and thus its anti-aging ability was enhanced, and the thermal oxidation of these four materials was first-order reaction. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47002.     

Fabrication of MWNTs/nylon conductive composite nanofibers by electrospinning

MWNT/nylon 6, 6 composite nanofibers were fabricated using an electrospinning method, and the electrical properties were examined as a function of the filler concentration. Initially, the pristine, purified MWNTs were treated with a 3:1 mixture of concentrated H₂SO₄/HNO₃ to introduce carboxyl groups onto the MWNT surface. The carboxylated MWNTs were then treated with thionyl chloride and an ethylenediamine solution for amide functionalization. FT-IR spectroscopy was used to examine the functionalization of the MWNTs. Nylon 6, 6 is readily soluble in formic acid. Therefore, the amide functionalized MWNTs were dispersed in formic acid. The solution remained stable and uniform for more than 40 h. –NH₂ termination of the MWNTs improved the dispersion stability of the MWNTs in formic acid. The MWNTs-suspended in a solution of nylon 6, 6 in formic acid was electrospun to obtain the nanofibers. The electrical properties of the nanofibers were examined as a function of the filler concentration. The results showed that the I–V properties of the nanofiber sheet improved with increasing filler concentration.     

Effect of nanoclay on the thermal,mechanical, and crystallization behavior of nanofiber webs of nylon‐6

Nylon‐6 and nanoclay/nylon‐6 composite nanofibers were prepared by electrospinning technique, in which formic acid was used as a solvent for good solubility of nylon‐6. The diameter of nylon‐6 and nanoclay/nylon‐6 nanofibers was below 350 nm and had smooth surfaces. The DSC heating curves of nylon‐6 and composites nanofibers show two endotherm behaviors, T_m1 (about 214°C) and T_m2 (about 220°C), corresponding to the melting events of γ‐form and α‐form crystals, respectively. The WAXs study showed that the γ‐crystalline phase predominantly present in both nylon‐6 and nanoclay/nylon‐6 nanofibers. The mechanical properties of the nanoclay/nylon‐6 composite nanofibers were higher than neat nylon‐6 electrospun nanofibers, which was decreased as the quantity of the clay increased. It might be due to the aggregation of nanoclay at high concentration. The thermal properties of the composite nanofibers were higher than neat nylon‐6 nanofibers. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Preparation and characterization of electrospun poly(ε‐caprolactone)–pluronic–poly(ε‐caprolactone)‐based polyurethane nanofibers

In this study, amphiphilic poly(ε‐caprolactone)–pluronic–poly(ε‐caprolactone) (PCL–pluronic–PCL, PCFC) copolymers were synthesized by ring‐opening copolymerization and then reacted with isophorone diisocyanate to form polyurethane (PU) copolymers. The molecular weight of the PU copolymers was measured by gel permeation chromatography, and the chemical structure was analyzed by ¹H‐nuclear magnetic resonance and Fourier transform infrared spectra. Then, the PU copolymers were processed into fibrous scaffolds by the electrospinning technology. The morphology, surface wettability, mechanical strength, and cytotoxicity of the obtained PU fibrous mats were investigated by scanning electron microscopy, water contact angle analysis, tensile test, and MTT analysis. The results show that the molecular weights of PCFC and PU copolymers significantly affected the physicochemical properties of electrospun PU nanofibers. Moreover, their good in vitro biocompatibility showed that the as‐prepared PU nanofibers have great potential for applications in tissue engineering. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43643.