二氧化碳-环氧丙烷共聚物电纺纤维形貌研究

利用电纺丝技术制备了二氧化碳环氧丙烷共聚物超细纤维,研究了喷丝口电势、纺丝距离、浓度、溶剂等因素对纤维形貌、直径及均一性的影响.实验结果表明,利用电纺丝法可以制备直径在小于200nm到7μm二氧化碳环氧丙烷共聚物纤维;喷丝口电势和浓度对于共聚物电纺丝纤维是否形成串珠结构有重要影响;电势、距离和纺丝液浓度都对纤维直径及分散系数有较大影响,在一定范围内,随着喷丝口电势增加,纤维平均直径变大而分散系数变小;纺丝距离增大使得纤维平均直径变小,分散系数变大;浓度的增大使得纤维平均直径变大,分散系数变小;不同溶剂配制的溶液体系制备的电纺丝纤维形貌有很大差异,在二氯甲烷和丁酮的体系中,分别观察到了两组较为集中的直径分布.     

静电纺丝法和气流-静电纺丝法制备聚砜纳米纤维

应用电纺法制备了聚砜纳米纤维.设计了一种新型的气流静电纺丝装置,其特点是在喷丝头上添加了喷气组件.电纺过程中所用聚砜的特性粘数为0.97dLg,溶剂为二甲基乙酰胺,载气为氮气.研究了聚砜纳米纤维的平均直径与过程参数之间的关系.研究表明影响聚砜纳米纤维的平均直径的主要因素为电压、纺丝液的流速、喷丝头与收集器之间的距离、操作温度以及纺丝液的性质(如粘度、表面张力和电导率).纳米纤维的平均直径和直径分布用扫描电镜表征.应用这种气流静电纺丝法制备的纳米纤维的直径范围是50～500nm.所得纳米纤维的直径依赖于电压、喷丝头与收集器之间的距离以及喷丝液的浓度.结果表明,采用气流静电纺丝不仅能制备较细而且均匀的纳米纤维,而且产量更高.     

静电纺丝制备图案化无机纳米纤维

静电纺丝技术近几年在制备纳米纤维领域得到了广泛的应用,被认为是批量制备纳米纤维材料最简单有效的方法。本文综述了近几年高压静电纺丝技术制备图案化无机物纳米纤维的纺丝装置和过程,特别详细综述了纺丝过程中纤维直径的变化,利用带电流体动力学(EHD)理论推导出纤维直径变化的运动方程,并对方程进行一定程度的修订,以符合电纺无机物纳米纤维直径的变化;并综述了取向纳米纤维、中空纳米纤维、壳-核结构纳米纤维、纳米线、纳米带、纳米管及多层次结构纳米纤维的构建及其基本性能。最后对电纺制备图案化无机纳米纤维未来发展方向,特别是功能化多层次结构电纺无机纳米纤维制备进行了展望。     

磁场辅助静电纺有序聚丙烯腈纳米纤维的研究

磁场辅助静电纺丝方法能够制备有序纳米纤维,但是其参数之间的匹配关系很少被研究。本文通过正交实验,对影响磁场辅助静电纺丝制备聚丙烯腈纳米纤维的四个工艺参数(溶液浓度、磁铁间距、纺丝电压和注射速度)在3个水平上进行优化筛选。以纤维直径大小、均匀度和纤维有序度为考察目标,同时考虑溶液浓度、磁铁间距与纺丝电压这三个因素之间的两两交互作用,结合极差分析、方差分析,发现溶液浓度是影响纤维直径和均匀度的高度显著因素,溶液浓度和纺丝电压的交互作用对直径均匀度有显著影响,纺丝电压是影响纤维有序度的显著因素。     

稳定射流电纺丝法制备定向排列的壳聚糖超细纤维

采用电驱动纺丝,以壳聚糖(CTS)为研究对象材料,通过引入超高分子量聚氧化乙烯(PEO)调节纺丝液的黏弹性,实现抑制电纺丝固有的射流不稳定弯曲摆动来得到单一的稳定射流,从而可以像传统工业上的干、湿法纺丝一样制备定向的超细CTS纤维(称为稳定射流电纺丝,SJES).系统地研究了SJES的工艺参数(如CTS/PEO质量比、纺丝电压、接收距离、凝固浴成分、辊筒转速等)对制备定向的超细壳聚糖纤维的影响,并通过SEM、FTIR、WAXD、纳米力学拉伸仪等研究了所制备纤维的形貌、结构与性能.结果表明,SJES法制备的CTS纤维直径在10μm以下,优化参数(如电压和辊筒转速)可使纤维直径细化到3μm左右.纤维单丝具有较高的力学性能,断裂强度和纤维模量可以分别达到(762±93)MPa和(11±6)GPa.稳定射流电纺丝方法制备的超细纤维与常规电纺丝法制备的纤维相比,具有较高的微晶取向度.     

电纺丝法制备聚乳酸/多壁碳纳米管/羟基磷灰石杂化纳米纤维的研究

电纺丝是一种利用聚合物溶液或熔体在强电场中进行喷射纺丝的加工技术,所制得的纤维、直径一般在数十纳米至几微米之间,比传统方法制得的纤维直径小几个数量级,是获得纳米尺寸长纤维的有效方法之一．     

磷钼酸/PMMA静电纺丝纤维的制备及形貌研究

通过静电纺丝技术制备了磷钼酸/PMMA复合纤维,研究了PMMA的相对分子质量、磷钼酸的含量及混合溶剂中DMF与乙醇的体积比对复合纤维形貌及直径的影响。通过扫描电镜(SEM)对复合纤维的形貌进行了观察,并测试了不同条件纺丝溶液的电导率、黏度和表面张力。研究发现,PMMA的相对分子质量和DMF与乙醇的体积比对复合纤维的形貌影响较为明显,磷钼酸的含量对复合纤维的直径影响显著。较为理想的纺丝条件为:PMMA的重均分子量为60000,纺丝液中磷钼酸的含量为16mg/mL,DMF与乙醇的体积比为6∶4。     

采用静电纺丝/非溶剂致相分离制备聚丙烯腈多孔超细纤维的研究

以聚丙烯腈/二甲基亚砜/N,N'-二甲基甲酰胺三元体系为纺丝液、3℃水浴为接收介质,通过静电纺丝制备了具有纳米孔结构的静电纺聚丙烯腈多孔超细纤维.探讨了溶剂比例、接收介质、聚丙烯腈浓度、纺丝电压及接收距离等因素对纤维直径和表面孔隙率的影响.结果表明最佳制备条件为混合溶剂质量比1∶1、纺丝电压16 kV、聚丙烯腈浓度15 wt%、接收距离5 cm、纺丝速率0.7 mL/h、环境温度25℃、相对湿度40%～70%.在此条件下得到的聚丙烯腈多孔超细纤维直径在420～490 nm,平均直径468 nm,表面孔隙率3.4%,纤维内部形成大量孔径为8～30 nm的孔结构,且孔径分布均匀,孔形状相对一致.N2吸附脱附测试表明,聚丙烯腈多孔纤维的BET比表面积达43.86 m2/g,是相同直径无孔聚丙烯腈纤维比表面积理论值的6倍.通过研究聚丙烯腈/(二甲基亚砜+N,N'-二甲基甲酰胺)/水的三元相图,提出非溶剂致相分离是主要成孔机理.     

静电纺丝法制备超细聚苯乙烯纳米纤维

采用静电纺丝方法制备了超细聚苯乙烯纤维, 通过向溶液中添加有机胺盐并降低溶液浓度将纤维的平均直径降至100 nm, 并研究了盐的添加量对纤维直径的影响.     

PCL/CeO_2杂化纤维的电纺制备与性能研究

首先利用静电纺丝技术制备了聚己内酯(Poly(ε-caprolactone),PCL)/稀土(Rare Earth,RE)杂化纤维,而后通过扫描电镜(SEM)、X射线衍射仪(XRD)、差示扫描量热仪(DSC)研究了静电纺丝电压、稀土加入量等因素对杂化纤维微观结构、直径以及热性能的影响。结果表明,加入RE后,杂化纤维中PCL具有多种晶体形态,且纤维表面具有微细的孔洞结构;随着RE加入量的增大,或随着静电纺丝电压的升高,纤维直径呈现先减小后增大的趋势,而纤维熔点呈现先增大后减小的趋势。     

静电纺聚丙烯腈纳米纤维晶态结构及取向的形成

采用新型流动水浴收集方式制备出连续单向排列的静电纺聚丙烯腈(PAN)纳米初生纤维,收集静电纺丝不同阶段的静电纺PAN纳米纤维,并在热水中进行后牵伸,使其伸长至原长的2倍、3倍.通过扫描电子显微镜(SEM)、广角X射线衍射(WAXD)等方法对静电纺丝过程不同阶段的PAN纳米纤维的形貌、直径、致密性、晶态结构及取向进行了表征.研究表明,(1)在静电纺丝过程中PAN纺丝液射流受到牵伸作用,静电纺PAN纳米纤维的晶态结构形成并逐渐完善.纳米纤维的直径随着静电纺丝过程逐渐减小(从664 nm减小至353 nm),结晶度从42.55％增加至47.76％,晶区取向由37.48％提高至43.93％.纳米纤维致密性也逐渐提高(密度由1.1917 g/cm3增加至1.1943 g/cm3).(2)静电纺丝过程进入PAN射流溶剂含量较低的阶段后,继续通过静电纺丝过程提高纳米初生纤维晶态结构及取向的效果很有限,而通过热水后牵伸过程可进一步使晶态结构及取向得到有效果的完善.研究同时发现,静电纺初生纤维的晶态结构及取向与其在热水牵伸过程中的进一步完善具有相关性.     

Fabrication of nanocomposite PAN nanofibers containing MgO and Al2O3 nanoparticles

This paper describes the effect of embedding MgO and Al₂O₃ nanoparticles on the diameter of electrospun composite polyacrylonitrile (PAN) nanofibers. Diameter of nanofibers determines the important properties of the nanofibrous mats used in a variety of developed applications such as tissue engineering scaffolds, drug delivery, catalysis, ultra filtration, sensors, and nanoelectronics. The results showed that the type and amount of nanoparticles dispersed in PAN solutions affect the conductivity as well as the viscosity of the electrospinning solutions. Increasing the amount of MgO and Al₂O₃ leads to higher conductivity and higher viscosity of the electrospinning solution and ultimately to a smaller nanofiber diameter. Moreover, the results showed that higher conductivity of the electrospinning solution overcomes the effect of higher viscosity. Finally, no interaction was detected between metal oxide nanoparticles and PAN macromolecules.     

掺杂羧基化碳纳米管的纳米碳纤维前驱体的制备及表征

为获得结构完整、 性能优良的纳米碳纤维前驱体, 采用静电纺丝法制备了掺杂羧基化多壁碳纳米管(MWCNTs)的聚丙烯腈(PAN)纳米纤维. 用扫描电子显微镜、 偏振红外光谱、 透射电子显微镜、 拉曼光谱及拉伸性能测试等对杂化纳米纤维的微观结构和力学性能进行了研究, 分析了MWCNTs含量的影响. 实验结果表明, 5%(质量分数)的MWCNTs掺杂量为杂化纳米纤维直径的突变点, 且MWCNTs的加入有利于PAN分子链的取向, MWCNTs在PAN纤维中大体上沿纤维轴向取向分布. 3%MWCNTs/PAN杂化纳米纤维的拉伸强度和拉伸模量分别达到88.6 MPa和3.21 GPa.     

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers prepared by atmospheric plasma treatment and electrospinning

Durable antibacterial Ag/polyacrylonitrile (Ag/PAN) hybrid nanofibers were prepared by atmospheric plasma treatment and electrospinning. Atmospheric helium plasma treatment was first used to reduce the AgNO₃ precursor in pre-electrospinning solutions into metallic silver nanoparticles, followed by electrospinning into continuous and smooth nanofibers with Ag nanoparticles embedded in the matrix. SEM, TEM, and EDX spectra were used to study the structure and surface elemental composition of the nanofibers. Silver nanoparticles, with diameters ranging between 3 and 6 nm, were found to be uniformly dispersed in the nanofiber matrix. The Ag/PAN nanofibers exhibited slow and long-lasting silver ion release, which provided robust antibacterial activity against both Gram-positive Bacillus cereus and Gram-negative Escherichia coli microorganisms.     

Polysulfone nanofibers prepared by electrospinning and gas/jet-electrospinning

Polysulfone nanofibers were prepared by electrospinning. The electrospinning equipment was designed in a new way, wherein the spinneret was combined with a gas jet device. The intrinsic viscosity of the used polysulfone was 0.197 dL/g in dimethyl acetamide, which was also the solvent in electrospinning. The gas used in this gas jet/electrostatic spinning was nitrogen. The relationship between the process parameters and the average diameter of polysulfone nanofibers was investigated. The main process parameters studied in this work were the voltage, the flow rate of the spinning fluid, the distance between the spinneret and the nanofiber collector and the temperature in the spinning chamber. The other important factors determining the nanometer diameter were the spinning fluid properties including its viscosity, surface tension and electrical conductivity. The average diameter and the diameter distribution of electrospinning nanofibers were measured experimentally by using scanning electron microscopy. The diameter of polysulfone nanofibers prepared by the gas jet/electrostatic spinning was in the range 50–500 nm. It was found that the diameter of nanofibers mainly depended on high voltage, the gap between the spinneret and the collector and the concentration of polymer solutions. It is concluded that the gas-jet/electrospinning is a better method than the conventional electrospinning, in that it makes the nanofibers finer and more uniform and exhibits higher efficiency in the process of electrospinning. __________ Translated from Acta Polymerica Sinica, 2005, (5) (in Chinese)     

Carbon nanofibers with nanoporosity and hollow channels from binary polyacrylonitrile systems

Carbon nanofibers with new structural features, e.g. nanoporosity, hollow, U-shape cross-section, were generated by utilizing the phase separation behavior of polymer additive with polyacrylonitrile (PAN). The approach involved the formation of precursor fibers by electrospinning of binary mixtures of PAN with poly(ethylene oxide) (PEO), cellulose acetate (CA) or poly(methyl methacrylate) (PMMA), the removal of the polymer and the carbonization of the remaining PAN. The carbon nanofiber yield was ca 50% of PAN in all cases. Nanoporous carbon nanofibers with an average diameter of 100 nm were generated from the water treated PAN/PEO precursors. Multi-channel hollow fibers (90-190 nm diameters) were produced from the acetone treated PAN/CA precursors. Carbon fibers produced from the chloroform treated PAN/PMMA precursors were 250-400 nm in diameters and consisted of varied hollow structures, i.e., hollow and U-shape cross-sections from those containing 30% and 50% PAN, respectively, and multi-channel hollow fibers from the 70/30 PAN/PMMA precursor. Carbonization of equal-mass PAN/PMMA as-spun fibers also produced similarly U-shape cross-sections as the chloroform treated ones, showing promise of direct carbonization. This simple and yet versatile approach to create new structural features in carbonized fibers has shown to depend on the distinct phase separation as well as the pyrolytic behaviors of the second polymer component.     

Parameter study and characterization for polyacrylonitrile nanofibers fabricated via centrifugal spinning process

Electrospinning is currently the most popular method for producing polymer nanofibers. However, the low production rate and safety concern limit the practical use of electrospinning as a cost-effective nanofiber fabrication approach. Herein, we present a novel and simple centrifugal spinning technology that extrudes nanofibers from polymer solutions by using a high-speed rotary and perforated spinneret. Polyacrylonitrile (PAN) nanofibers were prepared by selectively varying parameters that can affect solution intrinsic properties and operational conditions. The resultant PAN nanofibers were characterized by SEM, and XRD. The correlation between fiber morphology and processing conditions was established. Results demonstrated that the fiber morphology can be easily manipulated by controlling the spinning parameters and the centrifugal spinning process is a facile approach for fabricating polymer nanofibers in a large-scale and low-cost fashion.     

Enhancement of conductivity by diameter control of polyimide-based electrospun carbon nanofibers

Oxydianiline-pyromellitic dianhydride poly(amic acid) (ODA-PMDA PAA) was polymerized with a catalyst support of triethyl amine for controlling molecular weight. This polymer was used for electrospinning in the preparation of PAA nanofibers, a precursor of carbon nanofibers. Here the amount of catalyst and concentration of PAA solution were optimized to produce polyimide-based carbon nanofibers approximately 80 nm in diameter. The effects of molecular weight of PAA, bias voltage, and spinning rate on the morphology of electrospun PAA and polyimide nanofibers have been evaluated. We showed that the conductivity of the carbon nanofiber mat decreased with increasing nanofiber diameter, where the conductivity of polyimide-based carbon nanofiber mat was much higher than those of other types of carbon nanofiber mat. The key ingredient to increase conductivity in a carbon nanofiber mat was found to be the number of cross junctions between nanofibers.     

二氧化硅@聚合物同轴纳米纤维

The preparation and formation mechamsm ot silica/polyvinylpyrrolidone(PAN) coaxial nanofibers were presented in this paper. The PVP-PAN composite nanofibers were obtained via an electrospinning technique, while SiO2 nanoparticles were prepared according to a Stoeher method. The measurements of water contact angle(WCA), the compared results of silica coating PVPPAN composite nanofibers with PAN nanofibers indicate that much PVP resided on the composite nanofiber surface, which resuks in the occurrence of SiO2@polymer coaxial nanofibers due to the formation of hydrogen bonding between silica and composite nanofibers and subsequent adsorption of silica on the fiber surface.