聚乳酸的静电纺丝行为及其纤维结构研究

用静电纺丝法制备了纤维平均直径为350～1900nm的聚乳酸纤维,用扫描电镜研究了纤维的形貌,并用实验设计方法研究了纺丝工艺参数(溶液浓度、电场电压)对纤维平均直径的影响,同时用差示扫描量热分析和X射线衍射研究了静电纺丝所得纤维的结构.研究结果表明:溶液浓度对纤维的平均直径有较大的影响,溶液浓度较低时易形成珠状结构的纤维,纤维的平均直径随着聚合物浓度的增大而增大,并随电场电压的增大而减小.与浇铸膜相比,静电纺丝所制得的纤维有较低的结晶度,并且结晶结构不够完善.由静电纺丝制备的聚乳酸纳米纤维膜在组织工程和药物缓释等领域有潜在的应用前景.     

静电纺丝法制备高分子量聚左旋乳酸纳米纤维及其表征

利用静电纺丝法制备了高分子量聚左旋乳酸(PLLA)纳米纤维,研究了溶液浓度、纺丝距离和纺丝电压对纤维形貌的影响.用扫描电子显微镜(SEM)对纤维形貌进行了表征,结果表明,当PLLA溶液浓度为3%,纺丝距离为20.5cm,纺丝电压为13kV时得到的纤维形貌较好.再用差示扫描量热法(DSC)对纤维的热学性能进行了表征,用X...     

磁场辅助静电纺有序PAN/PVP复合纳米纤维的制备及工艺优化

磁场辅助静电纺丝(MFAES)技术能够制备有序纳米纤维,但其参数间的匹配关系很少被系统研究。通过MFAES方法制备了有序聚丙烯腈(PAN)/聚乙烯吡咯烷酮(PVP)复合纤维,应用正交实验分析了纺丝中主要的过程参数对复合纤维直径和有序度的影响。实验表明:随着浓度增大,复合纤维的直径增大,得到复合纤维的最小直径为496nm;溶液浓度和纺丝电压是复合纤维有序度的显著影响因素,在溶液浓度为14wt%、PAN/PVP配比为80∶20、纺丝电压为12kV、磁铁间距为2cm时,复合纤维的有序度最高达95%。     

醋酸纤维素导电纤维膜的制备及其电热性能研究

以醋酸纤维素(CA)为原料制备静电纺丝纤维膜，研究其可纺性能。结果表明，在CA的质量分数为10%～12%,纺丝距离为10～15cm,纺丝电压为12.5～17.5kV,丙酮/DMAc溶剂配比为6∶3的纺丝条件下，可以获得粗细均匀，表面平滑，且直径小于700nm的CA纳米纤维。将制备的纳米纤维膜脱乙酰化处理后，利用原位聚合法制备聚吡咯/醋酸纤维(PPy/D-CA)复合导电膜，并对其电热性能进行测试，结果表明PPy/D-CA复合导电膜具有较好的电热性能。     

静电纺丝参数对聚乙酸乙烯酯纤维形貌的影响

以N,N-二甲基甲酰胺(DMF)为溶剂,采用静电纺丝法制备了聚乙酸乙烯酯(PVAc)纤维.用场发射扫描电镜观察了PVAc纤维的形貌,研究了PVAc溶液质量分数、纺丝电压、收集距离等对纤维形貌及平均直径的影响.研究结果表明,PVAc溶液质量分数和纺丝电压对纤维的形貌有显著影响,随着PVAc溶液质量分数和纺丝电压的增大,纤维的平均直径增大;收集距离对纤维形貌的影响较小.尝试采用静电纺丝法制备了炭黑和PVAc的复合纤维,以增强纤维的导电性,成为导电碳纤维,但炭黑会显著降低PVAc的成纤性,因为它会吸附溶剂DMF,使溶剂在电纺过程中不易挥发,射流不能固化成纤维.     

静电纺丝制备P(3HB-co-4HB)/醋酸纤维素复合纳米纤维支架的性能及细胞相容性

采用静电纺丝法制备了一系列不同组成含量的3-羟基丁酸-4-羟基丁酸共聚物(P(3HB-co-4HB))/醋酸纤维素(CA)复合纳米纤维支架。通过扫描电镜、水相接触角和力学性能测试对复合纳米纤维支架的形貌、亲水性及力学性能进行了表征。结果表明,静电纺P(3HB-co-4HB)/CA复合纳米纤维均匀,平均直径在350~700nm之间,且呈相互贯通的三维多孔网状结构。随着CA含量的增加,复合纳米纤维支架的亲水性变好,但拉伸强度和断裂伸长率有所下降。体外降解实验发现,不同降解环境下P(3HB-co-4HB)/CA复合纳米纤维支架的降解速率不同,酶能加速复合纳米纤维支架的降解速率。鼠成纤细胞在复合纳米纤维支架表面能很好地粘附和铺展,表明P(3HB-co-4HB)/CA复合纳米纤维支架具有良好的细胞相容性,在组织工程支架材料领域具有广阔的应用前景。     

二醋酸纤维素多孔超细纤维的制备研究

以二氯甲烷/丙酮为溶剂,借助高挥发溶剂的制孔性,通过静电纺丝技术制备二醋酸纤维素多孔超细纤维。探讨了溶剂配比、溶液浓度对多孔超细纤维形貌的影响。通过扫描电镜观察纤维形貌,通过电导率仪测试纺丝液电导率,运用黏度计测试纺丝液黏度。结果表明,溶剂配比和溶液浓度是影响纤维形貌的重要因素。二氯甲烷体积比例由90%降低到30%的过程中,形貌由"柱状纤维"过度到"带状纤维"最终生成"颗粒状"。溶液浓度由2%(wt,质量百分数,下同)上升到5%时,形貌由"颗粒状"变为"带状纤维"最终生成有粗节的"柱状纤维"。     

基于TPEE双组分扭曲螺旋电纺纤维的初探

首先利用静电纺丝法制备了热塑性聚酯弹性体(TPEE)纳米纤维.用扫描电镜(SEM)对纤维的形貌进行了表征,纤维的直径为300～600nm,讨论了纺丝液浓度和纺丝距离对纤维形貌产生的影响.然后在一定的负电压下制备了聚对苯二甲酸丁二醇酯(PBT)和聚左旋乳酸(PLLA)电纺纳米纤维,发现PBT和PLLA均具有良好的负极可纺...     

负载金属氧化物纳米夹心材料的制备及抗菌性能

采用静电纺丝法制备了负载有不同含量金属氧化物的纳米TiO2/聚已内酰胺(PA6)及纳米TiO2/PA6/Ag纤维,通过扫描电镜(SEM)对纤维进行了表征,纤维直径在50nm～100 nm之间;讨论了纤维平均直径与溶液黏度及电导率之间的关系;实验选用霉茵作为测试菌种,采用振荡瓶法对纤维进行抗茵性能测试,结果表明,抗茵纤维...     

空气过滤用静电纺聚苯乙烯/碳纳米管复合纤维膜的制备

采用静电纺丝技术制备聚苯乙烯(PS)超细纤维、PS/多壁碳纳米管(MWCNTs)复合纳米纤维,并对其纤维形态结构、直径大小及空气过滤性能进行了表征。通过PS纺丝溶液浓度变化调控制备纯PS纤维多孔膜,并通过在PS纺丝液中添加不同含量MWCNTs调控纤维形态结构。SEM分析结果表明PS/MWCNTs复合纤维表面形成"褶皱"型和"山峰"型纳米级突起,复合纤维表面的粗糙度明显增加,且纤维直径明显减小。空气过滤性能测试结果发现这种多级结构使复合膜的过滤效率相比光滑的纯PS纳米纤维膜大幅提高,过滤性能得到明显改善。在85L/min气流速度下,PS/MWCNTs复合膜过滤效率高达99.95%,空气阻力为374.6Pa。选择尺寸较粗的微米级PS纤维(~2μm)和相对较细的纳米级PS/MWCNTs复合纤维(~800nm)进行混纺,调节复合膜堆积密度可使得混纺膜空气阻力降低到235.4Pa,仍能保持高的过滤效率(99.68%)。     

Ultrafine porous fibers electrospun from cellulose triacetate

Ultrafine porous cellulose triacetate (CTA) fibers were prepared by electrospinning with methylene chloride (MC) and a mixed solvent of MC/ethanol (EtOH) and their intra- and inter-fiber pore structures was investigated. Ultrafine porous CTA fibers electrospun with MC had isolated circular shape pores with a narrow size distribution in the range of 50–100 nm. In the case of ultrafine CTA fibers electrospun with MC/EtOH (90 / 10 v/v), they had interconnected larger pores in the range of 200–500 nm. These porous structures were induced by phase separation resulting from the rapid evaporation of solvent during the electrospinning process. However, non-porous corrugated fibers were obtained from MC/EtOH (85 / 15 v/v) and MC/EtOH (80 / 20 v/v) due to their lower vapor pressure. The pore sizes in ultrafine CTA fibers electrospun with MC showed a bimodal distribution centered at ∼17 and ∼64 nm. CTA fibers electrospun with MC/EtOH (90 / 10 v/v) showed the greatest porosity due to their larger intra-fiber pores and fiber diameter.     

电纺制备多孔Ni1-xZnxFe2O4超细纤维的结构与磁性能

采用静电纺丝技术结合后期的热处理制备了具有多孔结构的Ni_1-xZn_xFe₂O₄(x=0~0.8)超细纤维. 利用X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、场发射扫描电镜(FESEM)、低温N₂吸附-脱附和振动样品磁强计(VSM)对纤维样品的晶体结构、微观形貌、孔特征和室温磁性能进行了研究. 结果表明, 550℃焙烧2?h得到的多孔Ni_1-xZn_xFe₂O₄超细纤维均为单相尖晶石结构, 平均粒径约为25~30?nm, 纤维直径主要分布在200~500?nm之间, 且具有较大的长径比; 所制备的Ni_0.5Zn_0.5Fe₂O₄多孔纤维的孔结构主要以狭缝状介孔为主, 其平均孔径约为11?nm; 随着Zn含量x由0增加0.8, Ni_1-xZn_xFe₂O₄纤维的晶格常数a线性增大, A位的红外特征振动频率单调递减, 矫顽力由13.8?kA/m逐步减小到2.3?kA/m, 比饱和磁化强度先增大后减小, 在x=0.4时达到最大值66.8?A·m²/kg. 与相近尺寸的Ni-Zn铁氧体纳米粒子相比, Ni-Zn铁氧体超细纤维由于其形状各向异性而表现出更高的矫顽力.     

同步辐射小角X射线散射研究PAN原丝制备过程中孔结构的演变

采用同步辐射小角X射线散射研究了PAN原丝制备过程中纤维孔结构的演变。结果表明,在水洗工艺中,纤维孔隙较多、较大,孔径分布较宽,近似圆形;在热水牵伸工艺中,纤维孔隙仍较多、较大,孔径分布较宽,近似椭圆形,长轴约17 nm~21 nm,短轴约4 nm~11 nm;在干燥致密化工艺中,孔隙急剧减少、减小,孔径分布较窄,沿纤维轴向约7 nm~9nm,垂直纤维轴向约2 nm;经过蒸汽牵伸,孔隙又增多、增大,孔径分布变宽,孔隙沿纤维轴向被牵伸得很长,近似梭形;但是随后的松弛热定型又使孔隙减小,孔径分布变窄。     

Preparation and characterization of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) electrospun fibers

Ultrafine fibers of chitosan/poly(vinyl alcohol)/poly(vinyl pyrrolidone) (CS/PVA/PVP) were prepared via electrospinning. The structure and morphology of CS/PVA/PVP ultrafine fibers was characterized by the Fourier transform infrared (FT-IR) spectroscope and scanning electron microscope (SEM). Furthermore, the effects of the concentration of PVA, PVP and the electrospinning voltage on the morphology of ultrafine fibers were investigated the the SEM. When the concentration of PVA was at the range of 30wt%–40wt%, ultrafine fibers could be obtained. The diameter distributions of ultrafine fibers decreased when the electrospinning voltage increased from 20 to 30 kV. The rough surface fibers could be obtained after etching with CHCl₃.     

Nitrogen-and Oxygen-Containing Porous Ultrafine Carbon Nanofiber:A Highly Flexible Electrode Material for Supercapacitor

Herein, we report a simple and effective preparation of ultrafine CNFs(u-CNFs) with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile(PAN) and poly(methyl methacrylate)(PMMA)] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios(10/0, 7:3, 5:5 and 3:7)were chosen and found that the PAN/PMMA ratio of 3:7(PAN/PMMA-3:7) is the optimum one. BET analysis showed the specific surface area of the u-CNFs-3:7 was 467.57 m~2/g with an excellent pore volume(1.15 cm~3g~(-1)) and an average pore size(9.48 nm): it is about 25 times higher than the conventional CNFs(c-CNFs). TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber diameter of ~50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods,the u-CNFs-3:7 was used without any activation, chemical or mechanical modifications. The u-CNFs-3:7 showed a better specific capacitance of 86 F/g in 1 mol/L H_2SO_4 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3:7 an alternative choice to the existing CNFs for the supercapacitors.     

Superior prospect of chemically activated electrospun carbon fibers for hydrogen storage

In this study, the capacity of hydrogen storage was evaluated by using electrospun activated carbon fibers prepared by electrospinning and chemical activation based on the comparison with other carbon materials such as active carbon, single walled carbon nanotube, and graphite. For an improved hydrogen storage system, the optimized conditions of carbon materials were investigated with studying their specific surface area, pore volume, size, and shape. The hydrogen adsorption capacity of chemically activated electrospun carbon fiber itself is better than that of other porous carbon materials. This is attributed to the optimized pore structure of electrospun activated carbon fibers that might provide better sites for hydrogen adsorption than other carbon materials.     

A reactive electrospinning approach for nanoporous PLA/monetite nanocomposite fibers

Nanoporous fibers of PLA/monetite nanocomposite were fabricated using a reactive electrospinning approach using appropriate precursors. Monetite is formed in-situ during the electrospinning of PLA matrix. The crystal phase and morphological structure of the monetite/PLA fibers were characterized using X-ray diffraction and Scanning Electron Microscope. The monetite particles were uniformly distributed through the electrospun fibers. Water and heat were produced during the formation of monetite as by-products. Both water and heat had the ability to modify the surface of the electrospun PLA/monetite fibers. Water induced pore formation (WIPF) was the most likely mechanism to explain the pore formation during the reactive electrospinning process. Electrospinning parameters such as feed rate, spinning voltage and monetite contents in the composite fibers were correlated to pore formation in the fibers. The feed rate had a significant effect on the pore formation. There was a little decrease in the value of the BET surface area for the fibers electrospun at high rate compared to that of the fibers electrospun at low rate. At low spinning voltage of 10 kV, most surfaces were nonporous. However, at a greater voltage (e.g. 26 kV) the number of pores increased on the surfaces. As the monetite contents increased, the pores were produced in a longitudinal shape and surface became rough. The final morphology of the pore formation implies a competition between the amounts of the generated by-product water and heat. By controlling the electrospinning parameter, it is possibly to manipulate fibers with the controlled pore area.     

Fabrication of 1-dimensional porous hydroxyapatite and evaluation of its osteoconductivity

Porous HA ceramics with 1-dimensional pore channels were fabricated to obtain controllable microstructure. 1-dimensional porous HA was objected to find out the optimum condition of bone ingrowth and also to facilitate the observation of osteocondutive behavior in porous HA. The porous structure was formed by burnt-out of polymeric fibers and the size of pores was determined by the diameter of polymeric fibers. The porosity could be varied by the thickness of HA slurry coated on polymeric fiber and by the thickness of HA tapes inserted between fiber layers. As result, 1-dimensional porous HA ceramics of this study have the uniform interconnection size (50-500 microm) and the linearly open pore structure. The compressive strength of 1-dimensional porous HA was 6-10 MPa similar to that of human cancellous bone. On the in vivo test, oteon-like osteoconduction in pore channel of 1-dimensional porous HA was observed, like what had been found in cortical bones. This osteon-like new bone grew from the surface to the center of pore channels. The 1-dimensional porous HA ceramics prepared in this study were very useful as a model system to observe bone ingrowth in the porous HA implants.     

高比表面超细Ca(OH)_2粉体制备与表征

采用表面活性剂结构诱导下CaO消解法,通过降低反应体系表面张力,抑制Ca(OH)2晶体颗粒的生长及颗粒团聚,制备具有多孔特征的高比表面Ca(OH)2粉体颗粒。采用扫描电镜、X射线衍射、比表面积分析、孔结构等方法对样品进行了表征。结果表明:反应体系中表面活性剂种类与用量、m(H2O)∶m(CaO)比值对样品颗粒形态、比表面积、孔隙结构有影响。m(H2O)∶m(CaO)比值以及加入适量的表面活性剂时,可制备粒度为200～500nm的Ca(HO)2晶体颗粒,且样品具有多孔性,孔径分布均匀,为8～15nm。     

In situ encapsulation of horseradish peroxidase in electrospun porous silica fibers for potential biosensor applications

Nanoporous silica nanofibers have been employed as a matrix to encapsulate horseradish peroxide enzymes via a simple electrospinning method. A viscous solution of prehydrolyzed tetramethyl orthosilicate, beta-d-glucose, poly(vinyl alcohol), and enzymes were employed as spinning solution to generate porous fibers in the form of nonwoven mats. The silica fiber mats thus produced have a high surface area because of the small diameter (100 to 200 nm) of the fibers as well as the extreme porosity (2 to 4 nm) of individual fibers caused by the glucose template present in them. The high surface area, mechanical flexibility, thermal stability, reusability, and freedom of encapsulating various enzymes make porous silica nanofibers excellent biosensors.