同轴静电纺丝制备PCL-PLA芯-壳结构复合纤维及其形态分析

本文采用同轴静电纺丝技术制备聚己内酯(PCL)-聚乳酸(PLA)芯-壳结构复合纤维。通过扫描电子显微镜(SEM)观察芯层-壳层溶液推进速度、纺丝电压和收集距离对PCL-PLA复合纤维形貌的影响;通过透射电子显微镜(TEM)分析芯层-壳层溶液推进速度比对PCL-PLA芯-壳结构形成的影响。结果表明:当壳层溶液推进速度大于芯层时,形成了完整的芯-壳结构;另外,随着壳层溶液推进速度的增加,PCL-PLA复合纤维芯层含量降低;随着纺丝电压和收集距离的增加,PCL-PLA复合纤维平均直径减小。     

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%。     

静电纺丝工艺对PVP/TEOS/硝酸盐复合纳米纤维成纤性状的影响

采用静电纺丝技术制备了PVP/[Sr(NO3)2+Mg(NO3)2+TEOS+Eu(NO3)2+Dy(NO3)2]复合纳米纤维,研究了不同静电纺丝工艺参数对其成纤性状的影响。结果表明:纤维的直径均随着电压、无机盐和PVP含量的增加呈现先减小后增大的趋势;随着纺丝液中无机盐含量的增加,纺丝液的黏度、表面张力和电导率均逐渐增大;随着PVP含量的增加,纺丝液的黏度、表面张力逐渐增大、电导率先减小后增大。SEM分析表明,当纺丝电压在13~15kV,纺丝液中无机盐含量为5%~6%,PVP含量为15%时,易获得形貌较好的复合纳米纤维。     

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%)。     

PLGA载药纤维的制备及释药行为研究

PLGA(聚乳酸/乙醇酸共聚物)具有良好的生物降解性、相容性和降解产物无毒性等优点,且降解速率可由其分子量和共聚物组成比例来调控.本文采用静电纺丝法制备了以PLGA为壳层材料,聚乙烯基吡咯烷酮(PVP)、PLGA为内芯材料的同轴复合纤维,并研究了两种药物(5-氟尿嘧啶和番荔素)在纤维载体中的药物释放行为.在相同的释放环境中,与混纺纤维比较,同轴电纺得到负载了5-氟尿嘧啶的纤维在初期药物突释行为有所改善.同时,对于负载番荔素的同轴复合纤维,不同芯材样品能够表现出不同的释放行为.     

电纺PEI/PVP复合纳米纤维的制备与表征

利用静电纺丝技术制备了纳米级别的聚醚酰亚胺(PEI)/聚乙烯吡咯烷酮(PVP)复合纤维,考察了不同的纺丝工艺参数对PEI/PVP纤维形貌的影响。利用扫描电镜对纤维表面进行观察;通过红外光谱分析纤维中复合物间的相互作用;采用示差扫描量热分析(DSC)检测纤维的热性能。实验表明,以二氯甲烷(DCM)和N,N-二甲基乙酰胺(DMAC)为混合溶剂,体积比为5:1～6:1,聚醚酰亚胺与聚乙烯吡咯烷酮重量比为1∶1～1∶5范围内时,静电纺丝高压为12kV,流速为1mL/h时,使用混纺技术可获得表面光滑、粗细均匀的PEI/PVP复合纳米纤维,纤维直径在400～700nm之间。红外光谱和DSC结果表明,聚合物之间通过氢键作用、静电吸引发生相互作用而复合形成纳米纤维,并且复合纤维良好的保持了PEI优异的热稳定性。     

电纺复合纳米纤维对难溶药物增溶促渗作用研究

以75%(体积比)的乙醇水溶液为溶剂,将聚乙烯吡咯烷酮PVP K30、十二烷基硫酸钠(SDS)、阿魏酸(FA)按质量比30:1:10:w/v%配成共溶纺丝液,采用电纺工艺制备出多组分复合纳米纤维.场扫描电镜观察表明纤维膜具有立体三维连续网状结构,纤维结构均一、表面光滑,96%纤维直径在140～280nm之间.X射线晶体衍射和差示扫描量热结果表明FA和SDS能以分子状态高度复合分散于PVP纤维基材中,衰减全反射红外扫描结果表明SDS、FA、PVP之间能够通过氢键、静电吸引、疏水性能发生相互作用而复合.体外溶出与透膜结果表明复合纳米纤维具有改善药物溶出特征、促进药物透膜吸收的功能.     

静电纺丝法制备SiC纤维

以聚碳硅烷(PCS)和聚乙烯吡咯烷酮(PVP)为原料制得前躯体溶液,采用静电纺丝法制备出PCS/PVP前驱体纤维,经高温分解得到SiC纤维.X射线衍射证实纤维中生成了立方结构β-SiC相.采用扫描电子显微镜(SEM)对前驱体纤维及煅烧后SiC纤维的形貌进行了观察,所制备的SiC纤维直径很小,但均匀性不是很高,且表面依附一层非晶形SiO2薄膜层.     

静电纺丝法制备PVP/PVDF复合微/纳米纤维

研究了不同条件下聚乙烯吡咯烷酮/聚偏氟乙烯(PVP/PVDF)的N,N-二甲基乙酰胺(DMAc)溶液的静电纺丝.采用扫描电镜(sEM)观察不同条件下制备的PVP/PVDF复合微/纳米纤维的微观形貌,并利用傅立叶变换红外光谱分析(FT-IR)纤维结构特征.结果表明,当PVP:PVDF为6:4时,制得的PVP/PVDF复合微/纳米纤维较好.     

静电纺载银PVDF纳米纤维膜的制备及其在层压织物中的应用

采用静电纺丝技术制备了载银PVDF复合纳米纤维膜,以PVP为还原剂,探索了不同的PVDF与PVP质量比对所得纤维形貌的影响。加入AgNO3后,研究了反应温度、AgNO3添加量对纳米银生成情况的影响。还考察了纺丝时间对复合纳米纤维膜的水接触角、阻气性、保暖率、防雨性能的影响。研究结果表明,PVDF与PVP质量比为7∶3时纤维具有较好形貌,Ag+的最佳还原温度为60℃、添加量为0.09g/g。随纺丝时间的增加,复合纳米纤维膜的水接触角逐渐增大,层压织物的阻气值、保暖率也随之增大。     

Preparation and characterization of electrospun core sheath nanofibers from multi-walled carbon nanotubes and poly(vinyl pyrrolidone)

Electrospinning is a versatile technique to prepare polymer fibers in nano to micrometer size ranges using very high electrostatic fields. Electrospun nanofibers with tunable porosity and high specific surface area have various applications, including chromatographic supports for protein separation, biomedical devices, tissue engineering and drug delivery matrices, and as key components in solar cells and supercapacitors. Unspinnable materials such as nanoparticles, nanorods, nanotubes or rigid conducting polymers can also be electrospun into fibers through co-axial electrospinning. In this study, we have prepared core-sheath nanofibers utilizing co-axial electrospinning. The core portion of these electrospun fibers consists of multi-walled carbon nanotubes and the sheath portion is poly(vinyl pyrrolidone) (PVP). Various morphologies were obtained by changing both core and sheath solution concentrations. The core-sheath nanofibers were characterized by scanning electron microscopy and transmission electron microscopy, to confirm core-sheath morphology, thermogravimetric analysis, and mechanical strength testing. The electrical conductivity of the surfaces of poly(vinyl pyrrolidone) fibers and poly(vinyl pyrrolidone)-multi-walled nanotube fibers were both 10(-15) S/m. The highest bulk conductivity observed for the poly(vinyl pyrrolidone)-multi-walled nanotube fibers was 1.2 x 10(-3) S/m.     

A general synthesis for PEDOT-coated nonconductive materials and PEDOT hollow particles by aqueous chemical polymerization

A method for coating functionalized poly(3,4-ethylenedioxythiophene) (PEDOT) on nonconductive substrates in aqueous solution allows the deposition of PEDOT thin layers on various substrates, including silica and polystyrene (PS) nanoparticles, siliceous mesocellular foam, and chitosan-alginate fibers. The surface property is tuned by controlling the monomer composition in the aqueous solutions. Using appropriate organic solvents to remove the PS cores of PEDOT-coated PS nanoparticles, hollow PEDOT particles with single holes and PEDOT capsules can be formed.     

Characterization of hollow silica–polyelectrolyte composite nanoparticles by small-angle X-ray scattering

Hollow silica–polyelectrolyte composite nanoparticles were prepared using templates of spherical polyelectrolyte brushes which consist of a polystyrene (PS) core and a densely grafted linear poly(acrylic acid) shell. The obtained hollow particles were systematically studied by small-angle X-ray scattering (SAXS) in combination with other characterization methods such as transmission electron microscopy and dynamic light scattering. The hollow structure formed by dissolving the PS core was confirmed by the reduction of electron density to zero in the cavity through fitting SAXS data. SAXS revealed both the inward and outward expansions of the hollow silica–polyelectrolyte composite particles upon increasing pH from 3 to 9, while further increasing pH led to the partial dissolution of silica layer and even destruction of the hollow structure. SAXS was confirmed to be a unique and powerful characterization method to observe hollow silica nanoparticles, which should be ideal candidates for controlled drug delivery.     

Functionalized polymer spheres via one-step photoinduced synthesis for antimicrobial activity and gene delivery

Despite the fact that polystyrene (PS) spheres have been developed as polymeric carriers or matrices for various biomedical applications, the synthesis of PS spheres is time-consuming. This work describes the fabrication of a uniform PS sphere, coated with silver nanoparticles (Ag-PS), by simultaneous photoinduced polymerization and reduction fabricated using x-rays in aqueous solution without any initiator. The solution contains only styrene, silver ions (Ag(+)), and poly(vinyl pyrrolidone) (PVP) as a stabilizer. The proposed mechanism of the formation of the Ag-PS nanocomposite spheres involves the generation of radicals in the aqueous solution to induce PS polymerization and the reduction of Ag. The distribution of the sizes of the core PS spheres in the Ag-PS nanocomposite spheres was systematically examined as a function of irradiation time, concentration of styrene, and amount of PVP. Ag-PS nanocomposite spheres exhibit antimicrobial activity against bacteria (Escherichia coli and Staphylococcus aureus). Additionally, the cationic (vinylbenzyl)trimethylammonium (TMA) monomer was photopolymerized to form positively charged TMA-PS spheres as gene carriers with uniquely low cytotoxicity. Given these design advantages, the method proposed herein is simpler than typical approaches for synthesizing PS spheres with functionalized groups and PS spheres coated with Ag nanoparticles.     

Control of self organization in conjugated polymer fibers

We propose new strategy to facilitate the fabrication of conjugated polymer fiber with higher oriented structures, which focused on electrospinning of a blend solution of regioregular poly(3-hexylthiophene) (rr-P3HT) and poly(vinyl pyrrolidone) (PVP). SEM observation revealed that the blend system forms homogeneous composite nanofibers. This system exhibits the specific feature of strong interchain contribution of P3HT from UV-vis absorption, fluorescence spectroscopic, XRD, and photoelectron spectrometric (for HOMO levels) investigations. We also demonstrate the removal of the PVP component from the P3HT/PVP composite fibers through the selective extraction and such strong interchain stacking of pristine P3HT fiber mat can be remarkably maintained.     

In-situ formation of Cu metal crystals within nanostructured ZnO electrospun fibers

The in-situ synthesis of Cu/ZnO crystalline nanofibers is presented. The composite nanofibers are formed through the calcination and reduction of as-electrospun fibers consisting of poly(vinyl pyrrolidone) as well as Cu and ZnO precursors. The crystal structure and morphology of the synthesized fibers were characterized using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. The presence of well crystallized Cu and ZnO phases within the fiber was verified using XRD spectra and HRTEM images. To the best of our knowledge, this analysis confirms the first successful in-situ synthesis of a metal nanocrystal and ceramic polycrystalline electrospun fiber hybrid.     

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.     

PVP表面修饰不同形貌金银纳米粒子研究现状

聚乙烯吡咯烷酮(PVP)是一种重要的工业化大分子表面活性剂,由于其大分子结构的特殊性及生物适应性,使得PVP在制备金属纳米粒子过程中得到了广泛应用。近年来,有大量关于以PVP为大分子表面修饰剂制备不同形貌金属纳米粒子的文献报道。文中综述了以PVP为表面修饰剂,分别以乙二醇、乙醇、N,N-二甲基甲酰胺及水为溶剂,通过溶剂和PVP自身的还原作用,在不同反应条件下制备不同形貌金、银纳米粒子的研究现状,提出了不同溶剂体系中不同形貌金属纳米粒子的形成机理研究是未来该领域要解决的主要问题。     

Synthesis of anatase-silver nanocomposite fibers via electrospinning

There has been growing interest in new ways to produce composite nanofibers. Continuous TiO2 (anatase phase) nanofibers with silver nanoparticles were prepared successfully via sol-gel and electrospinning. A sol containing poly(vinyl pyrrolidone), titanium tetraisopropoxide, and silver nitrate was injected through a conductive capillary where high voltage was applied. As a result of electrospinning, continuous composite nanofibers were collected and they were calcined in air at 500 degrees C in order to complete the crystallization of anatase phase. The anatase-silver nanocomposite fibers were characterized with X-ray diffraction, field emission scanning electron microscopy, high resolution transmission electron microscopy, and energy dispersive X-ray spectroscopy.     

Solvothermal synthesis of magnetite hollow submicrospheres and mesoporous nanoparticles

Magnetite hollow submicrospheres and mesoporous nanoparticles have been synthesized by a solvothermal approach with assistant of hexamethylenetetramine (HMT) and poly(vinyl pyrrolidone) (PVP). Experimental results showed that the morphology of magnetite was transformed from hollow to solid submicrospheres with increasing amount of HMT. Moreover, without addition of PVP or appropriate addition of external water, mesoporous nanoparticles were obtained. A probable gaseous bubble template mechanism was proposed for the formation of magnetite hollow and mesoporous nanostructures based on experimental observations. Magnetic measurement results revealed that all of the samples were ferromagnetic at room temperature.