低压近场静电纺丝ZnO/PVDF复合微米纤维阵列的制备及压力传感性（英文）

利用低压近场静电纺丝技术制备了ZnO/PVDF(聚二偏氟乙烯)微米纤维平行阵列,通过光学显微镜、扫描电子显微镜(SEM)和X射线能量色散光谱(EDS)对ZnO/PVDF微米纤维进行了表征.该复合纤维的平均直径约为40μm.EDS分析测试证明ZnO纳米颗粒已经掺杂进入了平行微米纤维中.压电性能和电学性能测试结果表明,ZnO/PVDF微米纤维阵列的压电性能增强.研究结果表明,近场电纺丝ZnO/PVDF复合微米纤维阵列在压电型压力传感器和纳米发电机领域具有潜在的应用价值.     

ZnO/PAN亚微米复合纤维的制备及光催化性能

采用静电纺丝技术,以聚丙烯腈(PAN)和醋酸锌[Zn(Ac)2]为前驱物,制备了Zn(Ac)2/PAN复合纤维。利用六亚甲基四胺[(CH2)6N4]辅助的水热合成法,成功制备了具有异质结构的ZnO/PAN亚微米复合纤维。利用扫描电镜(SEM)、X射线能量色散光谱(EDS)、X射线衍射(XRD)、透射电子显微镜(TEM)和拉曼光谱(Raman)等对产物的形貌和结构进行表征。结果表明,ZnO纳米粒子均匀地生长在PAN纤维表面,形成了ZnO/PAN亚微米复合纤维。以罗丹明B为目标降解物,对光催化性能进行评价,结果表明,ZnO/PAN亚微米复合纤维具有良好的光催化活性。     

高β相聚偏氟乙烯基复合体系的制备及压电性能

为了提高聚偏氟乙烯(PVDF)的压电性能,需要寻找有效的途径来提高PVDF的电活性相(β相)含量。 通过水热法成功合成了Ag、ZnO以及二者复合(Ag-ZnO)的3种类型纳米粒子,并与PVDF共混形成PVDF复合薄膜。 通过表征PVDF复合材料的形貌,结晶性能和压电性能,可以发现Ag-ZnO复合纳米粒子的协同作用可以有效提高PVDF的结晶性能和压电性能。 此外,通过单轴拉伸可以使得所有PVDF膜的β相含量得到进一步提高,其中拉伸后的PVDF/Ag-ZnO纳米颗粒(P-C)的β相物质的量分数最高,达到70.0％,最佳的压电系数(d₃₃)达到了31.0 pC/N。     

具有抗菌性能的载药复合微纳米纤维的制备及其结构和性能表征

利用静电纺丝技术制备了一种具有抗菌性能的氧化锌(ZnO)/聚乳酸(PLA)/聚己内酯(PCL)载药微纳米纤维膜,并通过扫描电子显微镜(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)分别对复合膜的表面形态、元素组成和化学结构进行表征。通过抗菌实验评价了复合膜的抗菌性能,用紫外分光光度计测试复合膜在体外的药物释放行为。结果显示,以物理共混的方式将ZnO和氢溴酸高乌甲素(LAH)成功载入复合微纳米纤维;与PLA/PCL复合微纳米纤维膜相比,ZnO/PLA/PCL复合微纳米纤维膜表现出更好的抗菌效率。当ZnO含量为10%(wt)时,复合微纳米纤维膜具有最佳的抗菌性能;药物释放性能结果表明,ZnO/PLA/PCL复合微纳米纤维膜具有良好的药物缓释性能。     

Ag/ZnO纳米纤维的制备及光催化性能

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维, 然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面. 利用X射线衍射(XRD)、 X射线光电子能谱(XPS)、 能量色散X射线光谱(EDX)、 扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征. SEM结果表明, 直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构. 以常见的有机污染物甲基橙、 亚甲基蓝和罗丹明B等为降解底物, 对Ag/ZnO纳米纤维的光催化性能进行了表征. 结果表明, 负载银纳米颗粒后, 复合催化剂的光催化性能明显提高.     

离子液体中纤维素/纳米层状ZnO复合抗菌纤维的制备及性能

以表面活性剂十二烷基磺酸钠(SDS)为模板,Zn(NO_3)_2·6H_2O和NaOH为锌源和沉淀剂,通过改进的模板法在温和条件下制得纳米层状ZnO.以离子液体1-烯丙基-3-甲基咪唑氯盐([Amim]Cl)为溶剂,木浆纤维素和纳米层状ZnO为原料,采用溶液共混方法,通过干湿法纺丝制备了ZnO质量分数分别为3%,5%,7%及9%的纤维素/ZnO纳米复合纤维.采用X射线衍射(XRD)、X射线光电子能谱(XPS)、透射电子显微镜(TEM)、场发射扫描电子显微镜(SEM)及热重分析(TG)等方法对纳米层状ZnO及纤维素/ZnO复合纤维进行了表征,并探讨了ZnO的加入对复合体系流变性的影响,同时对复合纤维进行了力学和抗菌性能测试.研究结果表明,所制备氧化锌纯度高,且呈现出重复周期为3.58 nm的层状结构,抗菌性能优异.纳米层状ZnO的加入提高了纤维素纤维的热稳定性和机械强度,同时赋予纤维对金黄色葡萄球菌和大肠杆菌的抑菌性.ZnO片层被纤维素链剥离,并均匀分散于纤维素/ZnO复合物中.ZnO的加入增大了纤维素溶液的黏度,当ZnO含量达到5%以上时,在整个频率范围内,弹性模量大于损耗模量,纳米粒子可稳定悬浮.     

Ag/ZnO纳米纤维的制备及光催化性能（英文）

采用静电纺丝技术及煅烧法制备了氧化锌纳米纤维,然后采用水热法将银纳米颗粒负载到了氧化锌纳米纤维表面.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、能量色散X射线光谱(EDX)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)等技术对合成的Ag/ZnO纳米纤维的结构和组成进行了表征.SEM结果表明,直径在5~100 nm之间的银纳米颗粒附着在直径在80~330 nm之间的氧化锌纤维表面形成了异质结构.以常见的有机污染物甲基橙、亚甲基蓝和罗丹明B等为降解底物,对Ag/ZnO纳米纤维的光催化性能进行了表征.结果表明,负载银纳米颗粒后,复合催化剂的光催化性能明显提高.     

增强复合静电纺纳米纤维膜

静电纺丝纳米纤维膜具有孔隙率高、孔径小、透气性好等优良性能。但由于纤维太细,且纤维间没有有效的粘结,其强度较低,严重限制了它的应用。本文采用高/低熔点热熔性的两种高聚物进行混合静电纺丝,制备了聚丙烯腈/聚偏氟乙烯-六氟丙烯(PAN/PVDF-HFP)、聚偏氟乙烯/聚偏氟乙烯-六氟丙烯(PVDF/PVDF-HFP)复合纳米纤维膜,并通过110℃、3MPa、5min的热压后处理,使PVDF-HFP部分熔融,制得具有点粘结的增强复合纳米纤维膜。测试结果显示,较处理前,增强PAN/PVDF-HFP、PVDF/PVDF-HFP复合纳米纤维膜的拉伸断裂强度分别提高了923.1%和665.7%,达到17.8MPa和26.9MPa,且同时保留了优良的孔隙率与透气性能。     

Pt纳米花/ZnO复合阵列的制备及对甲醇氧化催化的研究

利用调控ZnO纳米棒阵列的疏水、亲水性,由电化学方法制备了Pt纳米花/ZnO(PtNF/ZnO)复合阵列.该复合阵列排列规则、尺寸均一、方向一致.每一根ZnO纳米棒的顶端都覆盖着由Pt纳米颗粒构成的Pt纳米花,具有大的比表面积.与以亲水性的ZnO纳米棒制得的覆盖Pt纳米颗粒的ZnO复合阵列(PtNP/ZnO)以及单独的Pt颗粒相比,PtNF/ZnO复合阵列对甲醇氧化具有更高的电化学催化活性.     

高性能聚偏氟乙烯基柔性压电材料的设计策略进展

压电现象在新能源开发、 传感、 医药材料设计及可穿戴电子设备中具有广泛的潜在应用, 并受到普遍重视. 在压电材料中, 聚偏氟乙烯(PVDF)及其共聚物因具有良好的柔韧性、 易加工性、 稳定性和生物相容性等优点而备受关注. 本文综合评述了近年来在制备工艺和材料复合两个维度提高PVDF基压电材料输出性能的研究进展. 在研究PVDF压电性原理的基础上, 阐释了流延法、 静电纺丝法、 拉丝法及纳米限域策略等工艺和添加小分子、 高分子、 石墨类粒子及无机纳米粒子等复合策略提升其压电性能的机理. 这些制备工艺的提高和填料的掺杂有助于偶极子的排列和高β相的形成. 最后, 对目前存在的一些挑战进行了概述和讨论, 并对PVDF基材料的发展前景提出展望.     

Microfluidic fabrication of β-phase enriched poly(vinylidene fluoride) microfibers toward flexible piezoelectric sensor

β-phase enriched piezoelectric poly(vinylidene fluoride) (PVDF) films/fibers are often prepared by high-energy costing methods, including mechanical stretching, high-electric field or electrospinning. In this study, PVDF piezoelectric microfibers, for the first time, were prepared by microfluidic spinning technology. The β-phase enriched PVDF microfibers with various diameters could be easily obtained inside the microfluidic channel due to the mass transfer induced phase inversion of the inner PVDF solution. The influence of diameter of the fibers, PVDF concentration of the inner phase and water content of the outer phase on the β-phase content and crystallinity degree of the obtained fibers was studied in detail. The obtained β-phase enriched fiber was weaved into meshes. Flexible piezoelectric fabrics were then developed based on these meshes, and further used as in-situ and real time human motion monitoring. This simple and effective strategy provides a promising microfluidic spinning technique toward the development of functional microfibers and wearable piezoelectric sensors, which may also give some implies for the industrial wet-spinning of piezoelectric PVDF fibers in the future.     

ZnO纳米线基MWNTs/PVDF复合热电材料的制备及特性研究

将不同比例的多壁碳管(MWNTs)与聚偏二氟乙烯(PVDF)聚合物混合后,喷涂于n型ZnO半导体纳米线阵列上,制备了一种新型ZnO纳米线基MWNTs/PVDF热电复合材料.与以往采用价格昂贵的p型与n型单壁碳纳米管(SWNTs)与聚合物混合制备的复合热电材料特性相比,这种新型热电复合材料在降低制造成本的同时,利用分散于聚合物中MWNTs的一维电子传输特性及形成的大量界面势垒,加上ZnO半导体纳米线具有的较高载流子密度与迁移率,提高了复合热电材料中电子的输运特性,增加了材料对声子的散射强度.测试发现,在一定的温度梯度下,随着MWNTs添加质量百分比的增加,热电材料的温差电动势和电导率也随之增加,但其Seebeck系数变化量不大.研究表明,这种热电材料有望替代采用p型与n型SWNTs构建的SWNTs/PVDF复合热电材料.研究结果对开发超轻、无毒、廉价、可应用于各种微纳电子领域的新型电源具有重要的参考价值.     

Free‐standing and flexible nano‐ZnO/PVDF composite thin films: impedance spectroscopic studies

Nanocrystalline ZnO‐impregnated polyvinylidene fluoride (nano‐ZnO/PVDF) composite films were prepared by sol‐gel technique. Free‐standing and flexible films with different nano‐ZnO loadings were synthesized. Addition of ZnO in PVDF host matrix modulated the impedance and dielectric properties. The composite films thus obtained were characterized by microstructural, XPS, and impedance spectroscopic measurements. Copyright © 2015 John Wiley & Sons, Ltd.     

Enhanced β‐phase in PVDF polymer nanocomposite and its application for nanogenerator

Harvesting energy from the ambient mechanical energy by using flexible piezoelectric nanogenerator is a revolutionary step toward achieving reliable and green energy source. Polyvinylidene fluoride (PVDF), a flexible polymer, can be a potential candidate for the nanogenerator if its piezoelectric property can be enhanced. In the present work, we have shown that the polar crystalline β‐phase of PVDF, which is responsible for the piezoelectric property, can be enhanced from 48.2% to 76.1% just by adding ZnO nanorods into the PVDF matrix without any mechanical or electrical treatment. A systematic investigation of PVDF‐ZnO nanocomposite films by using X‐ray diffractometer, Fourier transform infrared spectroscopy, and polarization‐electric field loop measurements supports the enhancement of β‐phase in the flexible nanocomposite polymer films. The piezoelectric constant (d₃₃) of the PVDF‐ZnO (15 wt%) film is found to be maximum of approximately −1.17 pC/N. Nanogenerators have been fabricated by using these nanocomposite films, and the piezoresponse of PVDF is found to enhance after ZnO loading. A maximum open‐circuit voltage ~1.81 V and short‐circuit current of 0.57 μA are obtained for 15 wt% ZnO‐loaded PVDF nanocomposite film. The maximum instantaneous output power density is obtained as 0.21 μW/cm² with the load resistance of 7 MΩ, which makes it feasible for the use of energy harvesting that can be integrated to use for driving small‐scale electronic devices. This enhanced piezoresponse of the PVDF‐ZnO nanocomposite film‐based nanogenerators attributed to the enhancement of electroactive β‐phase and enhanced d₃₃ value in PVDF with the addition of ZnO nanorods.     

Contact-Piezoelectric Bi-Catalysis of an Electrospun ZnO@PVDF Composite Membrane for Dye Decomposition

The treatment of organic pollutants in wastewater is becoming a great challenge for social development. Herein, a novel contact-piezoelectric bi-catalysis of a ZnO@ PVDF composite membrane was prepared by electrospinning technology. The obtained ZnO@PVDF composite membranes is superior to the pure PVDF membrane in decomposing methyl orange (MO) under ultrasonication at room temperature, which is mainly attributed to the synergy effect of the contact-electro-catalysis of dielectric PVDF, as well as the piezoelectric catalysis of tetrapodal ZnO and the β-phase of PVDF. The heterostructure of the piezoelectric-ZnO@dielectric-PVDF composite is beneficial in reducing the electron/hole pair recombination. As compared to the pure PVDF membrane, the catalytic degradation efficiency of the ZnO@PVDF composite membrane was improved by 444.23% under ultrasonication. Moreover, the reusability and stability of the composite membrane are comparable to those of the traditional powdered catalyst. This work offers a promising strategy for improving the pollutant degradation by combining contact-electro-catalysis with piezoelectric catalysis.     

Adhesion of biologically inspired vertical and angled polymer microfiber arrays

This paper proposes an approximate adhesion model for fibrillar adhesives for developing a fibrillar adhesive design methodology and compares numerical simulation adhesion results with macroscale adhesion data from polymer microfiber array experiments. A technique for fabricating microfibers with a controlled angle is described for the first time. Polyurethane microfibers with different hardnesses, angles, and aspect ratios are fabricated using optical lithography and polymer micromolding techniques and tested with a custom tensile adhesion measurement setup. Macroscale adhesion and overall work of adhesion of the microfiber arrays are measured and compared with the models to observe the effect of fiber geometry and preload. The adhesion strength and work of adhesion behavior of short and long vertical and long angled fiber arrays have similar trends with the numerical simulations. A scheme is also proposed to aid in optimized fiber adhesive design.     

Self-assembly of Hollow PNIPAM Microgels to Form Discontinuously Hollow Fibers

A new kind of hollow hydrogel microfiber with discontinuous hollow structure was prepared by an ice-segregation-induced self-assembly process. Monodisperse thermo-responsive hollow poly（N-isopropylacrylamide）（PNIPAM） microgels were first synthesized by seed precipitation polymerization using colloidal Si O2 nanoparticles as seeds, followed by removing the silica cores of the formed Si O2/PNIPAM core/shell composite microgels with hydrofluoric acid. Then, the discontinuously hollow hydrogel microfibers were produced by unidirectional freezing of 1 wt% hollow PNIPAM microgel aqueous dispersion in liquid nitrogen bath, followed by freeze-drying to remove the formed ice crystals. Many orderly arrayed dents were observed on the surfaces of the hydrogel microfibers by field-emission scanning electron microscopy, indicating that they are constructed by closely packed monodisperse hollow PNIPAM microgels. The effect of freezing method and the hollow microgel concentration in the aqueous dispersion on the morphological structure of the hollow hydrogel microfibers was investigated.     

Length‐Dependent Charge Generation from Vertical Arrays of High‐Aspect‐Ratio ZnO Nanowires

Aqueous chemical growth of zinc oxide nanowires is a flexible and effective approach to obtain dense arrays of vertically oriented nanostructures with high aspect ratio. Herein we present a systematic study of the different synthesis parameters that influence the ZnO seed layer and thus the resulting morphological features of the free‐standing vertically oriented ZnO nanowires. We obtained a homogeneous coverage of transparent conductive substrates with high‐aspect‐ratio nanowire arrays (length/diameter ratio of up to 52). Such nanostructured vertical arrays were examined to assess their electric and piezoelectric properties, and showed an electric charge generation upon mechanical compressive stress. The principle of energy harvesting with these nanostructured ZnO arrays was demonstrated by connecting them to an electronic charge amplifier and storing the generated charge in a series of capacitors. We found that the generated charge and the electrical behavior of the ZnO nanowires are strictly dependent on the nanowire length. We have shown the importance of controlling the morphological properties of such ZnO nanostructures for optimizing a nanogenerator device.     

Improving piezoelectric and pyroelectric properties of electrospun PVDF nanofibers using nanofillers for energy harvesting application

In this study, it was aimed to increase the piezoelectric and pyroelectric properties of electrospun polyvinylidene fluoride (PVDF) nanofibers simultaneously by using specific nanofillers. Graphene oxide (GO), graphene, and halloysite nanotubes with different concentrations (0, 0.05, 0.4, and 1.6% wt/wt) were combined with PVDF solution and were fabricated in the form of nanofibers through electrospinning. Pyroelectric properties of samples were measured by submerging sealed samples in hot water (360°K) and ice (270°K). The piezoelectric properties of the samples were evaluated through bending tests. The microstructural, mechanical, and thermal properties of the electrospun PVDF nanocomposite were investigated using scanning electron microscope, Instron instrument, and thermogravimetric analysis, respectively. To further support the experimental observations for generating electric voltage in the bended nanogenerator, the PVDF nanogenerator (PNG) was also modeled by a finite element analysis based on the theory of linear piezoelectricity using COMSOL Multiphysics simulation software. Experimental results showed that adding nanofillers could improve the piezoelectric and pyroelectric properties of all samples, associated with the increment of β‐phase in the nanofibers. It was concluded that adding nanofillers could increase pyroelectricity about 50% more than piezoelectricity in pristine PVDF nanofiber web. The PNG containing 1.6 wt% GO showed the highest efficiency in terms of piezoelectricity and pyroelectricity. In addition, the results showed that the ratio of piezoelectric to pyroelectric coefficients was constant (~1.5) and it was independent of the nanofiller type and content. The effect of external force and vibration frequency on the output voltage was also investigated. Increasing the compressive force and vibration frequency caused a greater output voltage. Finally, the fabricated nanogenerator was integrated on insole and elbow to investigate its energy harvesting capabilities from body movement.