Cleanable Air Filter Transferring Moisture and Effectively Capturing PM2.5

The lethal danger of particulate matter (PM) pollution on health leads to the development of challenging individual protection materials that should ideally exhibit a high PM_2.5 purification efficiency, low air resistance, an important moisture‐vapor transmission rate (MVTR), and an easy‐to‐clean property. Herein, a cleanable air filter able to rapidly transfer moisture and efficiently capture PM_2.5 is designed by electrospinning superhydrophilic polyacrylonitrile/silicon‐dioxide fibers as the adsorption–desorption vector for moisture‐vapor, and hydrophobic polyvinylidene fluoride fibers as the repellent components to avoid the formation of capillary water under high humidity. The desorption rate of water molecules increases from 10 to 18 mg min^?1, while the diameters of polyacrylonitrile fibers reduce from 1.02 to 0.14 µm. Significantly, by introducing the hydroxyl on the surface of polyacrylonitrile nanofibers, rapid adsorption–desorption of the water molecules is observed. Moreover, by constructing a hydrophobic to super‐hydrophilic gradient structure, the MVTR increases from 10 346 to 14 066 g m^?2 d^?1. Interestingly, the prepared fibrous membranes is easy to clean. More importantly, benefiting from enhanced slip effect, the resultant fibrous membranes presented a low air resistance of 86 Pa. A field test in Shanghai shows that the air filter maintains stable PM_2.5 purification efficiency of 99.99% at high MVTR during haze event.     

Mechanical and electrical properties of electrospun CNT/PVDF nanofiber for micro-actuator applications

Electrospun polyvinylidene fluoride (PVDF)-containing carbon nanotubes (CNT) were prepared for use in fabricating actuator materials. Actuating displacement was measured in an electrochemical environment. The electrospun nanofibers were arranged using a drum-type collector, and morphology was investigated using a field emission-scanning electron microscope. The uniformity of dispersion of CNT in the PVDF nanofibers was monitored by electron probe X-ray micro-analysis. Tensile strength and electrical resistivity results were used as an indication of the state of alignment. The electrospun CNT/PVDF nanofiber sheets exhibited better mechanical and electrical properties in the arranged direction. The efficiency and electrical capacities of electrospun CNT/PVDF nanofiber sheet were compared with those of cast PVDF sheets for use in actuator applications in electrochemical environments. The electrospun CNT/PVDF nanofiber sheets exhibited much better actuator performance than PVDF sheets, which are attributed to their superior electrical properties.

Highlights

(1) The interfacial durability of CNT/PVDF nanofibers was enhanced to increase contact area by reinforcing CNT.

(2) The efficiency of CNT/PVDF actuators was improved due to interfacial properties.

(3) Thin thickness drum-type collector was made to enhance nanofiber alignment.

(4) The arranged CNT/PVDF nanofibers exhibited better mechanical and actuating displacements.     

静电纺丝法制备超疏水氟硅改性纳米SiO_2/PET共混膜

利用1H,1H,2H,2H-全氟辛基三氯硅烷对SiO_2纳米粒子进行表面改性,制备得到氟硅改性SiO_2纳米粒子(M-SiO_2),并将其与聚对苯二甲酸乙二酯(PET)共混后溶于六氟异丙醇(HFIP)溶剂中进行静电纺丝。采用接触角测量仪、扫描电镜和X射线光电子能谱研究了M-SiO_2/PET电纺膜的疏水性能、表面形貌以及化学组成。结果表明,静电纺丝法制备的M-SiO_2/PET共混电纺膜对水的接触角可高达155.2°,并且对水的滞后角仅为3.4°,即具有超疏水性能。     

静电纺丝制备SU-8光刻胶纳米纤维及图案阵列

利用静电纺丝和紫外光刻技术直接制备了不同结构的SU-8光刻胶纳米纤维薄膜及图案阵列。通过光学显微镜和扫描电子显微镜表征了纳米纤维的形貌、尺寸及结构。结果表明,通过改变SU-8光刻胶的黏度可形成不同直径和形貌的纤维结构,其中用SU-8 3010和SU-8 3050光刻胶制备的纳米纤维具有最优的形貌,其平均直径分别为470 nm和610nm。利用带有长方形缺口的铝箔和同轴电纺的方法分别制备了平行趋向和空心结构的纳米纤维。通过紫外光刻过程,可将SU-8纳米纤维加工成点阵、条状等不同形貌的图案阵列或结构,有望用作细胞培养研究的功能基底材料。     

光子晶体纤维的制备及应用

光子晶体纤维是一种具有结构色的纤维,其无需染色就具有颜色亮丽、永不褪色、色彩饱和度高等特点,符合当前绿色、环保的要求,拥有广阔的发展前景。概述了光子晶体的原理、制备方法及应用,重点探讨了光子晶体纤维的制备方法,介绍了目前研究报道的多层膜干涉、自组装、电泳沉积、静电纺丝和热压印等方法,并讨论了这些方法的优缺点。     

一维纳米材料在锂离子电池中的研究进展

主要评述了近年来纳米棒、纳米管、纳米带、纳米纤维等一维纳米材料在锂离子电池正负极、隔膜及全固态电池固态电解质中的应用。一维纳米材料的比表面积大、孔隙率高,能为锂离子提供更短的嵌入脱出路径,还能有效缓解电池工作时产生的体积效应,从而大大提高锂离子电池的性能。介绍了不同方法制备的一维纳米材料在锂离子电池中对电化学性能的优化及提升,并重点介绍了具有产业化前景的静电纺丝法制备用于锂离子电池的一维材料近年的发展;展示了一维纳米材料在锂离子电池中的研究进展,并展望了其发展方向。     

静电纺丝法制备的Co0.6Ni0.3Cu0.1Fe2O4和Co0.6Ni0.3Zn0.1Fe2O4纳米纤维的结构及磁性能

采用静电纺丝技术制备出表面光滑、直径均匀的Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4/PVP和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4/PVP纳米纤维前驱丝,经500~900℃煅烧后得到Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维。用TG-DSC、XRD、SEM及VSM现代测试分析手段对Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的结构、形貌及磁学性能进行测试表征。结果表明:在空气气氛中经500~900℃煅烧后可得到纯尖晶石相、结晶度良好的纳米纤维或短纤维;当温度为700℃时,Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4和Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的形貌细长而光滑且直径相对均匀,大约为80nm;此时Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维则保有较高的剩磁比(M_r/M_s)及矫顽力,分别为0.56和1 088.87Oe。在500℃、600℃、700℃、800℃、900℃煅烧后,Co_(0.6)Ni_(0.3)Zn_(0.1)Fe_2O_4纳米纤维的饱和磁化强度分别比Co_(0.6)Ni_(0.3)Cu_(0.1)Fe_2O_4纳米纤维增大了14.5%、7%、16%、10.7%、8%,而矫顽力则分别降低了38%、51%、50%、46%、46.7%。两种纳米纤维的饱和磁化强度及矫顽力存在差异,为CoNi铁氧体在电磁方面的应用提供了很好的参考。