Tb3+掺杂Ca2Y8（SiO4）6O2荧光纳米纤维制备及发光性能

采用静电纺丝技术结合高温煅烧工艺,制备了稀土铽离子掺杂的氧基磷灰石型硅酸盐[Ca2Y8(SiO4)6O2:Tb3+]荧光纳米纤维。利用XRD,FT-IR,TG-DTA,SEM,HRTEM和荧光光谱仪等分析测试手段对样品的组成、结构和性能进行了表征。结果表明:前驱体纤维经800℃煅烧4 h后,获得的Ca2Y8(SiO4)6O2:Tb3+荧光纳米纤维,属于六方晶系,P63/m空间群,其平均直径为100 nm。在245 nm的紫外光激发下,Tb3+的发射光谱由蓝光区和绿光区两部分组成,前者在382,417和438 nm处的发射峰对应于Tb3+的5D3→7FJ(J=6,5,4)跃迁;后者在489,545,590和622 nm处的发射峰对应5D4→7FJ(J=6,5,4,3)跃迁,其中以5D4→7F5(545 nm)跃迁的发射峰为最强,呈现绿光特性,Tb3+的光致发光衰减曲线符合单指数行为,其荧光寿命达2.65 ms。     

Low generational polyamidoamine dendrimers to enhance the solubility of folic acid:A‘‘dendritic effect’’investigation

Low generational(G0–G2,G for generation) polyamidoamine(PAMAM) dendrimers were investigated as enhancers to improve the aqueous solubility of folic acid at pH 11 and pH 5.In these two cases,the solubility of folic acid increases with both the dendrimer concentration and generation.However,the solubilization mechanism is different.The electrostatic interaction between the primary amines of dendrimers and the ionized carboxylic groups of folic acid dominates the dissolution process at pH 11 while the increase of the solubility of folic acid at pH 5 is attributed to the hydrophobic encapsulation inside the dendrimer molecules.In addition,for comparison ethylenediamine was used as a small molecule control to examine the ‘‘dendritic effect' in the dendrimer-related solubilization process.Interestingly,PAMAM dendrimers exhibit,at pH 5,a significant superiority over ethylenediamine in enhancing solubility,whereas this ‘‘dendritic effect' cannot be observed under the basic condition.     

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。     

静电纺丝素/胶原/聚合物复合纤维的制备及其力学性能的研究

目前,将天然高分子蛋白和聚合物共混利用静电纺丝法制作各种组织工程支架材料倍受关注。基于这种研究背景,在本文中利用静电纺丝技术,制备了丝素(SF)/胶原(COL)/聚左旋乳酸(PLLA)和SF/COL/聚左旋乳酸-己内酯(PLCL)两种共混复合纤维膜,通过扫描电镜(SEM)对纤维形态结构分析,发现复合纤维形貌良好,直径较为均一。同时改变纺丝液中高分子蛋白的比例,复合纤维的直径也随之减小。此外,对复合纤维进行了力学性能测试,发现随着聚合物含量的增加,复合纤维膜的力学性能得以改善,SF/COL/PLCL组复合纤维的拉伸性能明显优于SF/COL/PLLA组。     

卟啉化聚合物纤维膜负载TiO_2光催化剂的制备及其光催化性能研究

通过烯基铁卟啉分别和苯乙烯、丙烯腈及甲基丙烯酸甲酯共聚制备三种卟啉化聚合物,然后利用静电纺丝技术将这三种卟啉共聚物与TiO2颗粒共纺制备卟啉共聚物纤维膜负载TiO2光催化剂。扫描电子显微镜(SEM)表征结果显示卟啉共聚物纤维负载TiO2催化剂都具有良好的纤维结构,纤维直径约为1.0-2.0μm。X-射线衍射仪(XRD)则表明TiO2的晶型在纺丝前后都没有受到明显影响。对甲基橙溶液的催化降解实验结果显示:铁卟啉-丙烯腈共聚物负载TiO2催化剂的光催化活性最高,而且铁卟啉的含量对催化剂催化活性起着非常重要的作用。优化后的铁卟啉-丙烯腈共聚物纤维膜负载TiO2光催化剂对甲基橙溶液的脱色率达到76.3%,同时纤维膜结构有利于催化剂的回收和重复使用。     

Electrospinning of nylon-6,6 solutions into nanofibers: Rheology and morphology relationships

The relationship between the rheological properties of nylon-6,6 solutions and the morphology of their electrospun nanofibers was established. The viscosity of nylon-6,6 in formic acid(90%) was measured in the concentration range of 5 wt%-25 wt% using a programmable viscometer. Electrospinning of nylon-6,6 solutions was carried out under controlled parameters. The chemical structure, morphology and thermal properties of the obtained nanofibers were investigated using Fourier transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM) and differential scanning calorimetry(DSC), respectively. Entanglement concentration(ce) was found to be 15 wt% and a power law relationship between specific viscosity and solution concentration was observed with exponents of 2.0 and 3.3 for semi-dilute unentangled(c ce) and semi-dilute entangled(c ce) regimes, respectively. The diameter and uniformity of the nanofibers were found to be dependent on the viscosity. Moreover, the average diameter of electrospun nanofibers was found to be dependent on zero shear rate viscosity and normalized concentration(c/ce) in a power law relationship with exponents of 0.298 and 0.816, respectively. For nylon-6,6 solutions, the entanglement concentration(ce = 15 wt%) provides the threshold viscosity required for the formation of a stable polymeric jet during electrospinning and producing uniform beadless fibers. For concentrations less than ce, beaded fibers with some irregularities are formed. DSC analysis showed an increase in crystallinity of all electrospun samples compared to original polymer. Furthermore, Based on FTIR spectroscopy, α phase is dominant in electrospun nanofibers and minor amount of β and γ phases is also available.     

静电纺丝技术在燃料电池中的应用

静电纺丝是一种简单、实用的制造纳米纤维的技术,所需设备少,易于大规模生产。本文主要从催化剂、固体聚电解质膜及膜电极三方面阐述了静电纺丝技术在低温燃料电池中的应用。静电纺丝制得的一维纳米线电催化剂具有稳定的循环性能、优异的传质能力及较低的成本;制备的固体聚电解质膜主要包括Nafion复合膜、阻醇膜及耐温膜,其性能相对于传统的Nafion膜得到了进一步提升,而且,通过采用静电纺丝技术,使膜电极结构得到了优化。最后,对静电纺丝技术在低温燃料电池应用过程中可能存在的问题及其未来的发展趋势进行了展望。     

介孔SBA-15棒负载的Pd3Cl催化剂催化Sonogashira偶联反应（英文）

通过静电吸引策略将具有高度分散性的原子精确纳米团簇[Pd3Cl(PPh2)2(PPh3)3]+(Pd3Cl)负载在介孔SBA-15棒上。结构明确的Pd3Cl/SBA-15催化剂在以水作为溶剂以及温和的反应条件下对催化Sonogashira碳-碳偶联反应展现了较好的催化性能以及循环性。在此基础上,我们研究了Pd3Cl团簇结构与性能之间的关系,并证实内核的Pdδ+(0<δ<2)与配体之间的协同效应是催化反应的关键。     

脉动热管的毛细管结构和尺度效应实验研究

脉动热管的毛细管结构变化如何影响其性能是研究者关注的问题.本文对毛细管截面为正方形和正三角形,水力直径范围为1 mm左右的回路型脉动热管的传热性能进行了实验研究.结果表明,角管脉动热管的倾角变化时,底加热明显优于顶加热;三角形截面脉动热管的热阻比正方形截面脉动热管的热阻更低.脉动热管在水力直径为1.5 mm时比1mm时的性能要好.实验研究为理论分析打下了基础.     

新型氮氧化钽/氧空位钨酸铋S型异质结纤维用于高效光催化降解抗生素和还原六价铬:产物毒性分析和光催化机理研究（英文）

近年来,环境污染问题严重地威胁着人类的生存和健康.半导体光催化是一种绿色环保的治理环境污染技术,该技术实现大规模应用的关键在于构建高效的光催化剂.TaON因优异的光电性质、稳定的物理化学性质及适合的能带结构等优势,被广泛应用于光催化水裂解和有害污染物降解等领域.但光生载流子快速复合和比表面积小等问题严重制约了其大规模应用.近年来,人们发现构建新型S型异质结能有效促进光生电子和空穴分离,同时充分保存具有强氧化还原能力的电子和空穴,进而有效提升材料的光催化性能.因此,通过构建新型TaON S型异质结光催化材料有f望开发出高效的可见光光催化体系.本文采用静电纺丝-煅烧-氮化工艺制备出由纳米颗粒组成的多孔TaON纳米纤维,然后采用溶剂热法制得一系列富含氧空位的TaON/Bi₂WO₆ S型异质结纤维,并用于可见光照射下光催化降解抗生素和还原Cr⁶⁺.实验发现,富含氧空位的Bi₂WO₆二维纳米片均匀生长在TaON纳米纤维上形成了良好的1D/2D核壳结构,此异质结界面结构有利于界面间电荷的分...