添加Al2O3对Ni0.5Zn0.5Fe2O4纳米纤维结构和磁性能的影响

采用静电纺丝技术制备了添加0～20wt%Al2O3的Ni0.5Zn0.5Fe2O4纳米纤维。通过XRD、FESEM、TEM和VSM对样品的物相结构、形貌和磁性能进行了表征。结果表明,所合成的复合纳米纤维的直径都分布在40～150 nm之间,添加到纤维中的Al2O3主要以非晶态形式分布于铁氧体晶粒边界;随着Al2O3添加量的增加,可观察到γ-Fe2O3相逐渐析出,Ni-Zn铁氧体的晶格常数单调减小,说明有一些Al2O3进入到尖晶石晶格中取代了B位的Fe3+离子,Ni-Zn铁氧体的平均晶粒尺寸先增大后减小,在Al2O3添加量为8wt%时达到最大值39.2 nm;比饱和磁化强度和矫顽力随Al2O3添加量的增加呈现出相同的变化规律,先减小后增大,当Al2O3添加量超过5wt%时又开始变小。     

原位水热合成SrTiO3/TiO2复合纳米纤维及光催化性能

以利用静电纺丝技术制备的TiO2纳米纤维为模板和反应物,原位水热合成了具有异质结构的SrTiO3/TiO2复合纳米纤维.采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能量散射光谱(EDS)、高分辨透射电子显微镜( HRTEM)和X射线光电子能谱(XPS)等测试手段对样品的结构和形貌进行了表征.用罗丹明B(RB)模...     

Preparation and characterization of porous TiO_2/ZnO composite nanofibers via electrospinning

<正>Porous TiO_2/ZnO composite nanofibers have been successfully prepared by electrospinning technique for the first time.It was generated by calcining TiO_2/ZnCl_2/PVP[PVP:polyvinyl pyrrolidone)]nanofibers,which were electrospun from a mixture solution of TiO_2,ZnCl_2 and PVP.Transmission electron microscopy(TEM) and X-ray diffraction(XRD) analyses were used to identify the morphology of the TiO_2/ZnO nanofibers and a formation of inorganic TiO_2/ZnO fibers.The porous structure of the TiO_2/ZnO fibers was characterized by N_2 adsoption/desorption isotherm.Surface photovoltage spectroscopy(SPS) and photocatalytic activity measurements revealed advance properties of the porous TiO_2/ZnO composite nanofibers and the results were compared with pure TiO_2 nanofibers,pure ZnO nanofibers and TiO_2/ZnO nanoparticles.     

Fabrication and characterization of polycrystalline WO3 nanofibers and their application for ammonia sensing

We describe the fabrication and characterization of tungsten oxide nanofibers using the electrospinning technique and sol-gel chemistry. Tungsten isopropoxide sol-gel precursor was incorporated into poly(vinyl acetate)(PVAc)/DMF solutions and electrospun to form composite nanofibers. The as-spun composite nanofibers were subsequently calcinated to obtain pure tungsten oxide nanofibers with controllable diameters of around 100 nm. SEM and TEM were utilized to investigate the structure and morphology of tungsten oxide nanofibers before and after calcination. The relationship between solution concentration and ceramic nanofiber morphology has been studied. A synchrotron-based in situ XRD method was employed to study the dynamic structure evolution of the tungsten oxide nanofibers during the calcination process. It has been shown that the as-prepared tungsten oxide ceramic nanofibers have a quick response to ammonia with various concentrations, suggesting potential applications of the electrospun tungsten oxide nanofibers as a sensor material for gas detection.     

Electrospun fibers from poly(methyl methacrylate)/vapor grown carbon nanofibers

Electrospinning has been used to obtain poly(methyl methacrylate) (PMMA) microfibers and nanofibers and PMMA/vapor grown carbon nanofibers (VGCNFs or CNFs) composite fibers with micrometer and nanometer size diameters. Thermogravimetric analysis (TGA) indicated that addition of CNFs caused a decrease in the thermal stability of the composite fibers. Scanning electron microscopy (SEM) was used to confirm the micro‐ and nano‐ nature of the fibers and transmission electron microscopy (TEM) was utilized to confirm the presence of CNFs embedded within the polymer matrix and along the surface. Copyright © 2006 John Wiley & Sons, Ltd.     

The Construction of Au/Carbon Nanocomposite Material,Characterization and Their Application in Catalytic Reaction of Styrene Epoxidation

The composite nanofibers from Au nanoparticles/carbon nanofibers (Au/CNFs) were fabricated through electrospinning, chemical reduction and high-temperature calcination methods. The polyacrylonitrile acted as the carbon precursor polymer. A series of characterization methods, which include UV–Vis diffuses reflectance spectra, UV–Vis spectra, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray diffraction respectively, were used to investigate the morphology and properties of catalysts. The result showed that the gold nanoparticles were well-distributed in/on the CNFs. In the end, the composite material was applied to epoxidation of styrene to investigate its catalytic activity.     

Preparation and characterization of composite nanofibers of polycaprolactone and nanohydroxyapatite for osteogenic differentiation of mesenchymal stem cells

Nanocomposites of nanohydroxyapatite (nHAP) dispersed in poly(?-caprolactone) (PCL) were prepared by electrospinning (ES) to obtain PCL/nHAP nanofibers. Nanofibers with similar diameters (340 ± 30 nm) but different nHAP concentrations (0-50%) were fabricated and studied for growth and osteogenic differentiation of bone marrow mesenchymal stem cells (MSCs). The nanofibrous membranes were subjected to detailed analysis for its physicochemical properties by scanning electron microscopy (SEM), thermogravimetric analysis, X-ray diffraction, Fourier-transform infrared spectroscopy, and mechanical tensile testing. nHAP particles (~30 nm diameter) embedded in nanofibers increased the nanofibrous membrane's ultimate stress and the elastic modulus, while decreased the strain at failure. When cultured under an osteogenic stimulation condition on nanofibers, MSCs showed normal phenotypic cell morphology, and time-dependent mineralization and osteogenic differentiation from SEM observations and alkaline phosphatase activity assays. The nanofibers could support the growth of mesenchymal stem cells without compromising their osteogenic differentiation capability up to 21 days and the enhancement of cell differentiation by nHAP is positively correlated with its concentration in the nanofibers. Energy dispersive X-ray analysis of Ca and P elements indicated mineral deposits on the cell surface. The mineralization extent was significantly raised in nanofibers with 50% nHAP where a Ca/P ratio similar to that of bone was found. The present study indicated that electrospun composite PCL/nHAP nanofibrous membranes are suitable for mineralization of MSCs intended for bone tissue engineering.     

Novel mechanism for spinning continuous twisted composite nanofiber yarns

Highly aligned and twisted composite Nylon 6 nanofibers incorporating multiwall carbon nanotubes (MWCNTs) were successfully electrospun, using a novel mechanism. It has been found that; ultrasound combined with high speed shearing is the simplest and most convenient method to improve the dispersion of MWCNTs into a polymer matrix with a certain loading. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were conducted to characterize the morphology of nanofibers, the dispersion of MWCNTs and their alignment inside the fiber body. By manipulating the electrical forces during electrospinning and applying mechanical stretching to the electrospun nanofibers, high polymer chain orientation and better alignment of the MWCNTs particles along the fiber axis was achieved. Twist was applied to the nanofibers for providing the required inter fiber lateral cohesion interaction and friction thus, spinning a continuous twisted composite yarn. SEM images show twisted yarns with diameters ranging between 5 and 10 μm. The twist effect of the parallel bundle was investigated by controlling the twist per unit length using a motor speed controller at values of 100, 250, 500, 750 and 1000 rpm. The paper also provides a comprehensive review of various yarn spinning mechanisms of electrospun nanofibers.     

Preparation and characterization of CNTs/PE micro‐nanofibers

Multiwalled carbon nanotubes (CNTs)/polyethylene micro‐nanofibers with content ranging from 0.5 to 10 wt% of CNTs were prepared for the first time by melt extrusion of immiscible blends with cellulose acetate butyrate (CAB) and subsequent removal of CAB matrix. The morphology development of dispersed phase was studied with samples collected at different zones in a twin‐screw extruder. The morphology of the CNTs in PE was found to be in forms of both individual and agglomerations. The average diameters of CNTs/PE nanofibers increased with increasing the CNTs content. The electrical conductivity of CNTs/PE nanofibers was studied and a percolation threshold of about 4 wt% was obtained. In addition, the crystalline structures of the CNTs/PE nanofibers were analyzed, indicating a decrease in the crystallinity with the addition of CNTs. The thermal properties of composite fibrils were also modified. This paper demonstrates a good approach for the preparation of CNTs/TP nanofibers by in situ microfibrillar formation. Copyright © 2011 John Wiley & Sons, Ltd.     

静电纺丝技术制备Y_2O_3∶Yb~(3+),Er~(3+)上转换纳米纤维及其表征

采用静电纺丝技术制备了PVA/[Y(NO3)3+Yb(NO3)3+Er(NO3)3]复合纳米纤维,将其在适当的温度下进行热处理,得到Y2O3∶Yb3+,Er3+上转换纳米纤维.XRD分析表明,复合纳米纤维为无定形,Y2O3∶Yb3+,Er3+上转换纳米纤维属于体心立方晶系,空间群为Ia3.SEM分析表明,复合纳米纤维的平均直径约为150nm;随着焙烧温度的升高,纤维直径逐渐减小.经过600℃焙烧后,获得了直径约60nm的Y2O3∶Yb3+,Er3+上转换纳米纤维.TG-DTA分析表明,当焙烧温度高于600℃时,复合纳米纤维中水分、有机物和硝酸盐分解挥发完毕,样品不再失重,总失重率为83%.FTIR分析表明,复合纳米纤维与纯PVA的红外光谱一致,当焙烧温度高于600℃时,生成了Y2O3∶Yb3+,Er3+上转换纳米纤维.该纤维在980nm的半导体激光器激发下发射出中心波长为521,562nm的绿色和656nm的红色上转换荧光,分别对应于Er3+离子的2H11/2/4S3/2→4Il5/2跃迁和4F9/2→4Il5/2跃迁.对Y2O3∶Yb3+,Er3+上转换纳米纤维的形成机理进行了讨论.     

Thermal and mechanical properties of nanofibers-based form-stable PCMs consisting of glycerol monostearate and polyethylene terephthalate

An innovative type of nanofibers-based form-stable composite phase change materials for the storage and retrieval of thermal energy was successfully prepared by encapsulating glycerol monostearate (GMS) into the porous structure of polyethylene terephthalate (PET)-supporting matrices on the nanoscale through electrospinning. The field-emission scanning electron microscopy and transmission electron microscopy images revealed that the composite nanofibers possessed desired morphologies with the average fiber diameters ranging from about 290 to 1000 nm which increased with the contents of GMS. The two phase separation (e.g., GMS phase and PET phase) was clearly observed from the images. When GMS content reached 60 %, the amount of the GMS distributing on the surface of the composite nanofibers was significantly increased during the electrospinning. The Fourier transform infrared spectroscopy spectrum proved that the PET supporting matrices were physically combined with GMS molecules. The differential scanning calorimetry analysis indicated that the GMS/PET composite nanofibers had reversible phase change behaviors, and the melting enthalpies increased from 32.63 to 66.99 kJ kg^?1 with increasing GMS amount. The TG results showed that both the onset thermal degradation temperature and charred residue of the GMS/PET composite nanofibers at 700 °C were higher than those of pristine GMS powder owing to the better thermal stability of the PET molecules. The tensile testing revealed that the averaged tensile strength and elongation at break of the all GMS/PET composite nanofibers varied from 3.29 to 10.30 MPa and from 2.42 to 42.30 %, respectively.     

Synthesis,Morphological Structures,and Material Characterization of Electrospun PLA:PCL/Magnetic Nanoparticle Composites for Drug Delivery

The effects of pure and impure magnetic nanoparticles (MPs) with three different concentrations (0.01, 0.1, and 1 wt %/v) on the morphological structure, crystallinity level, thermal properties and constituent interactions of electrospun poly(lactic acid) (PLA): poly(ε‐caprolactone) (PCL)‐based composites were investigated by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), and drug release tests using UV–vis spectrophotometry. Tetracycline hydrochloride (TCH), as a typical therapeutic compound, was loaded into these composite fibrous structures to study their application for drug delivery. The infrared spectra of composite nanofibers confirm the successful embedding of MPs into the fibrous networks. The addition of pure MPs increased the solution viscosity and thus promoted the MP dispersion inside the electrospun composite fiber mats. Impure MPs led to considerably lower average fiber diameters, and could generate unique cell structures that were reported for the first time in this study. The accelerated release of TCH was found by adding pure MPs to PLA:PCL blends. This characteristic was reflected in the parameters of Ritger‐Peppas and Zeng models, which were well fitted to our experimental drug release data. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013 , 51, 1607–1617     

YF3:Eu3+纳米纤维/高分子复合纳米纤维的制备与表征

采用静电纺丝技术制备了Y2O3:Eu3+纳米纤维,使用NH4HF2为氟化剂,经双坩埚法氟化和脱氨后得到YF3:Eu3+纳米纤维,再采用静电纺丝技术制备了YF3:Eu3+纳米纤维/PVP复合纳米纤维. XRD分析表明,立方相的Y2O3:Eu3+氟化后,得到了正交相的YF3:Eu3+纳米纤维,空间群为Pnma;YF3:Eu3+纳米纤维/PVP复合纳米纤维具有明显的YF3:Eu3+的衍射峰. SEM分析表明,YF3:Eu3+纳米纤维与YF3:Eu3+纳米纤维/PVP复合纳米纤维的直径分别为91±11 nm、319±43 nm,表面光滑. 用Shapiro-Wilk方法检验,纤维直径属于正态分布. 荧光光谱分析表明,YF3:Eu3+纳米纤维和YF3:Eu3+纳米纤维/PVP复合纳米纤维的最强发射峰均位于588 nm和595 nm,属于Eu3+的5D0→7F1跃迁,表明Eu3+占据YF3基质中Y3+晶格点的C2对称格位. PVP对YF3:Eu3+发光峰位没有影响,但发光强度降低;YF3:Eu3+的含量与YF3:Eu3+纳米纤维/PVP复合纳米纤维的发光强度成线性关系.     

SnO2/TiO2复合纳米纤维的制备及光催化性能

采用静电纺丝技术,以聚乙烯吡咯烷酮和钛酸正丁酯为前驱体,制得锐钛矿相TiO2纳米纤维。以TiO2纳米纤维为模板,通过水热合成法,制备了具有异质结构的SnO2/TiO2复合纳米纤维。利用扫描电镜(SEM)、X射线能量色散光谱（EDS）、透射电镜(TEM)和X射线衍射(XRD)等分析测试手段对其形貌和结构进行了表征,结果表明,SnO2纳米粒子均匀地生长在TiO2纳米纤维表面,形成了异质结构的SnO2/TiO2复合纳米纤维材料。通过改变反应物浓度,能有效地实现SnO2/TiO2复合纳米纤维的可控合成。以罗丹明B为模拟污染物,考察了SnO2/TiO2复合纳米纤维的光催化性能,与纯TiO2纳米纤维相比光催化活性明显提高,初步探讨了光催化反应机理。     

晶相可控的ZrO2纳米线的无卤制备及表征

采用无卤法制备晶相可控的ZrO₂纳米线. 通过静电纺丝法制备聚乙烯吡咯烷酮(PVP)与Zr(NO₃)₄的复合纤维; 再通过煅烧法在除去聚合物模板的同时制备ZrO₂纳米线. 采用X射线衍射(XRD)、 扫描电子显微镜(SEM)、 透射电子显微镜(TEM)、 傅里叶变换红外光谱(FTIR)仪及热重差热联用热分析仪(DSC-TGA)对材料的晶相结构、 形貌及热稳定性进行表征. 通过改变煅烧温度, 可以实现ZrO₂纳米材料形貌及晶相组成的调控.     

p-CuO/n-In_2O_3异质结纳米纤维的制备及气敏特性

以电纺In_2O_3纳米纤维为模版,通过溶剂热法构建了p-CuO/n-In_2O_3异质结纳米纤维.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X射线衍射(XRD)和X射线光电子能谱(XPS)等方法对所得材料的形貌和结构进行表征.结果表明,CuO纳米颗粒可以均匀地负载在超细In_2O_3纳米纤维表面;随着反应液中乙酸铜浓度的增加,负载的CuO纳米颗粒密度也逐渐增加.通过制备旁热式气敏器件对复合纳米纤维材料的气敏特性进行了研究.结果表明,与纯In_2O_3纳米纤维相比,p-CuO/n-In_2O_3异质结纳米纤维对H_2S气体具有较高的灵敏度和较低的工作温度.     

Y掺杂的ZnO纳米纤维材料的制备及其气敏传感器作用机理

采用静电纺丝法成功制备了Y掺杂的ZnO纳米纤维.并通过X射线衍射(XRD),扫描电子显微镜(SEM),能量色散X射线(EDX),透射电子显微镜(TEM)以及热重差热分析(TG-DTA)等手段对样品的结构和形貌进行了表征分析.同时用纯的ZnO和Y掺杂的ZnO纳米纤维制备了传感器,对浓度为(1-200)×10^-6 (体积分数)丙酮的气敏特性进行了测试分析.测试结果表明,可以通过简单控制纳米纤维中Y的含量,来微调该传感器的气敏特性.同时也发现通过Y掺杂, ZnO纳米纤维对丙酮的气敏特性有所改善,表现出很高的响应.纯ZnO和Y掺杂ZnO制成的传感器对几种潜在干扰气体表现出良好的选择性,比如氨气、苯、甲醛、甲苯以及甲醇.本文最后也讨论了该传感器的气敏作用机理.     

Electrospinning of zein/chitosan composite fibrous membranes

<正>Zein/chitosan composite fibrous membranes were fabricated from aqueous ethanol solutions by electrospinning. Poly(vinyl pyrrolidone)(PVP) was introduced to facilitate the electrospinning process of zein/chitosan composites.The asspun zein/chitosan/PVP composite fibrous membranes were characterized by scanning electron microscopy(SEM) and tensile tests.SEM images indicated that increasing zein and PVP concentrations led to an increase in average diameters of the composite fibers.In order to improve stability in wet stage and mechanical properties,the composite fibrous membranes were crosslinked by hexamethylene diisocyanate(HDI).The crosslinked composite fibrous membranes showed slight morphological change after immersion in water for 24 h.Mechanical tests revealed that tensile strength and elongation at break of the composite fibrous membranes were increased after crosslinking,whereas Young's modulus was decreased.     

聚(丙交酯-co-乙交酯)/β-磷酸三钙复合物的电纺研究

对生物可吸收聚(丙交酯-co-乙交酯)(poly(lactide-co-glycolide),PLGA)与β-磷酸三钙(-βTCP)复合物体系进行了电纺.研究了PLGA的浓度,-βTCP与PLGA比例,加料速度,电压,喷头与接收体之间的距离等因素对电纺过程的影响,制备出纳米纤维膜,并用扫描电镜(SEM)等对纤维膜进行表征.结果表明,电纺溶液浓度越高,或者加料速度越快,纳米纤维的直径越粗.力学实验显示,复合物中-βTCP的含量增加使纳米纤维膜的拉伸强度和杨氏模量下降.     

Structural evolution and magnetic properties of SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript> nanofibers by electrospinning

The SrFe₁₂O₁₉/poly (vinyl pyrrolidone) (PVP) composite fiber precursors were prepared by the sol-gel assisted electrospinning with ferric nitrate, strontium nitrate and PVP as starting reagents. Subsequently, the M-type strontium ferrite (SrFe₁₂O₁₉) nanofibers were derived from calcination of these precursors at 750–1,000 °C.The composite precursors and strontium ferrite nanofibers were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and vibrating sample magnetometer. The structural evolution process of strontium ferrite consists of the thermal decomposition and M-type strontium ferrite formation. After calcined at 750 °C for 2 h the single M-type strontium ferrite phase is formed by reactions of iron oxide and strontium oxide produced during the precursor decomposition process. The nanofiber morphology, diameter, crystallite size and grain morphology are mainly influenced by the calcination temperature and holding time. The SrFe₁₂O₁₉ nanofibers characterized with diameters of around 100 nm and a necklace-like structure obtained at 900 °C for 2 h, which is fabricated by nanosized particles about 60 nm with the plate-like morphology elongated in the preferred direction perpendicular to the c-axis, show the optimized magnetic property with saturation magnetization 59 A m² kg⁻¹ and coercivity 521 kA m⁻¹. It is found that the single domain critical size for these M-type strontium ferrite nanofibers is around 60 nm.