同轴电纺制备纳米纤维影响因素的研究进展

同轴静电纺丝技术制备的核-壳复合结构纳米纤维已取得了显著成果,在众多领域都具有较大的应用价值。通过对传统静电纺丝和同轴静电纺丝进行比较,分析了同轴静电纺丝的特点,并指出复合泰勒锥体和喷射流的稳定性直接影响着复合纳米纤维的形貌。重点讨论了纺丝过程中诸如黏度、浓度、电纺性、溶剂挥发性等溶液参数和流速、电压等工艺参数对核-壳结构纳米纤维形貌的影响作用,并探讨了流速对纤维成丝性的影响。最后归纳了核-壳结构纳米纤维在能源、组织工程、传感器等领域的优势和潜在应用。     

静电纺丝技术制备三维纳米结构研究进展

静电纺丝技术可制备形貌可控并且连续的纳米纤维,在三维纳米结构制备领域得到了广泛应用。综述了国内外三维静电纺丝技术的研究现状,介绍了三维静电纺丝技术的基本原理。概述了目前制备三维纳米结构常用的四种静电纺丝技术涉及的方法,即自组装法、固体模板辅助收集法、液体辅助收集法和气体辅助收集法。对制备原理、实验装置、制备方法、所获得的纳米纤维的主要工艺参数及适用范围进行了比较和总结,并且详细分析了影响其纺丝质量的因素,为三维静电纺丝技术进一步发展提供了参考。     

静电纺丝技术制备光学功能纳米纤维

介绍了静电纺丝制备纳米纤维的基本原理、装置及运用静电纺丝技术制备的实芯、空芯、多孔和带状等几种不同结构的纳米纤维,阐述了近年来同内外研究者通过静电纺丝技术制备出的发光纳米纤维以及光学偏振纳米纤维的相关成果及研究进展,并讨论了这类光学功能纳米纤维潜在的应用.     

静电纺丝技术在锂离子电池硅基负极结构的应用进展

作为锂离子电池的负极,硅是最有应用前景的材料之一。但其体积变化大、固体电解质膜(SEI)形成不稳定、导电性差的问题制约了研究的深入。静电纺丝技术是纳米纤维制造领域中常用的技术手段之一,为解决硅基材料所存在的问题提供了有效的方法。介绍了静电纺丝技术的原理和不同领域的应用;综述了近几年国内外静电纺丝技术在硅/碳、硅/金属复合材料的结构构筑领域的应用,着重从纳米纤维、核壳、蛋黄-蛋壳及多孔等复合结构方面进行概述,并总结了不同结构对于硅基负极材料性能的影响;针对静电纺丝技术在不同领域应用中所存在的问题,提出了今后研究的重点和方向,为静电纺丝技术的进一步发展提供了参考。     

ZnS∶Mn/PVA复合纳米纤维的制备及性能分析

采用绿色化学方法、通过使用对环境友好无危害的橄榄油,结合静电纺丝技术,成功制备了ZnS∶Mn/PVA复合纳米纤维。通过扫描电镜和X射线衍射对复合纳米纤维结构进行表征,通过光致发光研究了复合纳米纤维的光学性质。扫描电镜结果表明ZnS∶Mn/PVA复合纳米纤维的直径约为300 nm,X射线衍射仪结果显示ZnS∶Mn/PVA复合纳米纤维具有ZnS立方闪锌矿结构。光致发光光谱表明ZnS∶Mn/PVA复合纳米纤维在590 nm处具有较强的尖锐发射峰,实现了Mn2+的特征发射。ZnS∶Mn/PVA复合纳米材料是一种非常好的发光材料,有望在光电领域得到应用。     

基于静电纺丝技术的Ag/PVP纳米纤维的可控制备研究

为克服银纳米抗菌剂的不稳定性和使用量大等问题,本研究选用PVP为保护剂,DMF为溶剂及还原剂,还原AgNO3制备Ag纳米粒子,并添加一定比例的PVDF配制成纺丝液。通过静电纺丝技术成功制备了Ag/PVP/PVDF复合纳米纤维,并通过SEM、UV-Vis、EDS等对其进行了表征。     

静电纺丝法制备钇铁石榴石单晶纳米纤维

介绍了用静电纺丝法制备钇铁石榴石(YIG)磁光单晶纳米纤维材料的研究工作,其主要制备方法是将合成YIG所需金属元素的醇盐溶解于有机溶剂,通过静电纺丝法制备出了复合超细纤维,然后进行热处理,得到晶态磁光纳米纤维.对制备的复合纤维和热处理后的磁光纤维作了扫描电镜(SEM)分析,对热处理后的纤维作为了透射电镜(TEM)和X射线衍射(XRD)测试.通过对测试结果的分析发现,在纺丝过程中微量注射泵的推进速度和空气相对湿度是主要影响因素,推进速度和相对湿度减小,都有利于成丝.复合纤维的直径在500 nm～1 000 nm之间.经过750℃热处理后,样品仍然能保持纤维状结构,纤维直径在100 nm左右,并能够合成出单晶钇铁石榴石相.     

静电纺丝纤维应用的研究进展

首先简要阐述了静电纺丝装置和原理,然后着重讨论了静电纺丝纤维应用研究进展,即仿生支架、药物载体、各类型电池、传感器和催化剂,最后分析了制约静电纺丝纤维应用的因素。在静电纺丝纤维应用方面主要呈现的特点是应用领域非常广,这主要是基于静电纺丝纤维的纳米级直径、高孔隙率和大比表面积等优点,但大多数静电纺丝纤维应用都处在实验应用型阶段,距真正生产应用阶段还有一定距离。制约静电纺丝纤维应用的因素主要归结为两点,即电纺装备制约和电纺原理制约。今后静电纺丝技术将主要从装备优化和理论创新这两大方面入手,推动静电纺丝纤维由实验应用型向生产应用型转变。     

毛刷状ZnO@PVDF复合纳米纤维柔性压电纳米发电机

采用静电纺丝技术并通过两步低温水热法制备了“毛刷”状的氧化锌(ZnO)@聚偏二氟乙烯(PVDF)复合纳米纤维膜。结果表明，氧化锌纳米棒(ZnO NRs)均匀地径向生长在PVDF纳米纤维的表面，FTIR分析发现ZnO@PVDF复合纳米纤维膜β相含量相比PVDF纳米纤维膜从72.3%提升到85.6%,增加了18.4%。ZnO@PVDF复合压电纳米发电机(PENG)输出电压可达4.9 V,短路电流为293 nA。在外部负载电阻达到13 MΩ时，ZnO@PVDF复合PENG达到最大输出功率0.93μW。ZnO@PVDF复合PENG可以为电容器充电，电容放电时成功点亮LED小灯泡。此外，在5000次的循环敲击测试中，ZnO@PVDF复合PENG具有稳定的输出电压，有望作为无源设备的自供电电源得到广泛应用。     

基于量子棒纳米纤维大面积定向排列的偏振增亮膜及其在宽色域显示中的应用

作为一种新兴的纳米材料,CdSe/CdS量子棒的偏振发光特性使其在应用于新型液晶显示中极具潜力,而如何将量子棒材料在宏观尺度上大面积的定向排列是实现该技术的关键性问题。在本文中,我们报道了一种大面积、含定向排列量子棒、基于PMMA纳米纤维制成的偏振增亮膜。首先,采用一种新的TBP辅助合成方法,合成出具有核壳结构的CdSe/CdS量子棒。该材料的绝对量子产率达到了60%,发光波长的半峰宽为25nm,具有182nm的大Stokes位移。随后将这些量子棒溶于氯仿、DMF和PMMA混合溶液中制备用于静电纺丝的纺丝液。通过静电纺丝技术,将含有量子棒的聚合物纳米纤维通过滚筒收集处理,得到了一张透明、大面积、偏振增强的增亮膜,5cm~2增亮膜的偏振度为0.45。最后将制备的增亮膜嵌入一个液晶显示模组中测试,结果显示该模组的亮度提高了18.4%。这一结果表明我们制备的量子棒增亮膜在新型宽色域高光效显示领域具有非常广阔的应用前景。     

Highly Sensitive,Wearable, Durable Strain Sensors and Stretchable Conductors Using Graphene/Silicon Rubber Composites

Highly sensitive, wearable and durable strain sensors are vital to the development of health monitoring systems, smart robots and human machine interfaces. The recent sensor fabrication progress is respectable, but it is limited by complexity, low sensitivity and unideal service life. Herein a facile, cost‐effective and scalable method is presented for the development of high‐performance strain sensors and stretchable conductors based on a composite film consisting of graphene platelets (GnPs) and silicon rubber. Through calculation by the tunneling theory using experimental data, the composite film has demonstrated ideal linear and reproducible sensitivity to tensile strains, which is contributed by the superior piezoresistivity of GnPs having tunable gauge factors 27.7–164.5. The composite sensors fabricated in different days demonstrate pretty similar performance, enabling applications as a health‐monitoring device to detect various human motions from finger bending to pulse. They can be used as electronic skin, a vibration sensor and a human‐machine interface controller. Stretchable conductors are made by coating and encapsulating GnPs with polydimethyl siloxane to create another composite; this structure allows the conductor to be readily bent and stretched with sufficient mechanical robustness and cyclability.     

Polyacrylonitrile Nanofibers: Formation Mechanism and Applications as a Photoluminescent Material and Carbon‐Nanofiber Precursor

The facile synthesis of polyacrylonitrile (PAN) nanofibers is achieved using a microemulsion polymerization. The detailed formation mechanism of polymer nanofibers is examined using electron microscopy and UV‐vis and Fourier transform infrared spectroscopies, and the optoelectronic properties are studied by confocal laser scanning microscopy. The effects of surfactant properties, such as concentration, chain length, and ionic character, as well as monomer structure and polymerization temperature, on the structure of the resulting polymer nanofibers are also investigated extensively. Importantly, PAN nanofibers exhibited novel photoluminescence (PL), which is observed for the first time. The PL of PAN nanofibers is significantly different from that of PAN nanoparticles. The PAN nanofibers are also used as a precursor for carbon nanofibers. The carbonization temperature has a dominant effect on the degree of crystallinity of the resulting carbon nanofibers. This study is the first demonstration of the fabrication of polymer and carbon nanofibers using a convenient polymerization technique.     

Individual Dissolution of Single‐Walled Carbon Nanotubes by Using Polybenzimidazole,and Highly Effective Reinforcement of Their Composite Films

Polybenzimidazole (PBI) is shown to individually dissolve/disperse single‐walled carbon nanotubes (SWNTs) in N,N‐dimethylacetamide (DMAc), which is demonstrated by vis‐near IR absorption and photoluminescence spectroscopy and atomic force microscopy observations. By casting these dispersions, SWNTs/PBI composite films were successfully fabricated on substrates without any sign of macroscopic aggregation. The thermal stability and mechanical properties of the composite films were investigated using thermogravimetric analysis (TGA) and tensile tests, respectively, and it was found that, first, the addition of SWNTs to PBI does not deteriorate the thermal stability of the matrix film, and second, the mechanical properties of the PBI film were reinforced by ca. 50% with only 0.06 wt % addition of the SWNTs to the film without reducing the thermal stability of the PBI. Raman spectroscopy of the composite films revealed the existence of an interaction between the PBI and the SWNTs. The individual dissolution of the SWNTs and efficient reinforcement of the PBI are due to the π–π interaction between the PBI and the sidewalls of the SWNTs.     

Biomimetic Chitin–Silk Hybrids: An Optically Transparent Structural Platform for Wearable Devices and Advanced Electronics

The cuticles of insects and marine crustaceans are fascinating models for man‐made advanced functional composites. The excellent mechanical properties of these biological structures rest on the exquisite self‐assembly of natural ingredients, such as biominerals, polysaccharides, and proteins. Among them, the two commonly found building blocks in the model biocomposites are chitin nanofibers and silk‐like proteins with β‐sheet structure. Despite being wholly organic, the chitinous protein complex plays a key role for the biocomposites by contributing to the overall mechanical robustness and structural integrity. Moreover, the chitinous protein complex alone without biominerals is optically transparent (e.g., dragonfly wings), thereby making it a brilliant model material system for engineering applications where optical transparency is essentially required. Here, inspired by the chitinous protein complex of arthropods cuticles, an optically transparent biomimetic composite that hybridizes chitin nanofibers and silk fibroin (β‐sheet) is introduced, and its potential as a biocompatible structural platform for emerging wearable devices (e.g., smart contact lenses) and advanced displays (e.g., transparent plastic cover window) is demonstrated.     

Synthesis and morphological characterization of PMMA/polyaniline nanofiber composites

Poly (methyl methacrylate) (PMMA)/Polyaniline nanofibers composite films were prepared by solution casting. Doped polyaniline self-assembled nanofibers (PANFs) were synthesized by interfacial polymerization performed in an aqueous HCl/dichloromethane biphasic system in the presence of ammonium peroxydisulfate as oxidant agent. Sodium dodecyl sulfate (SDS) was added to the organic phase in order to verify possible modification the morphology the nanostrucutures when compared with previous reports. Treatment in an ultrasonic bath of PANFs on butanone resulted in a green dispersion (up to 250 mg/dL). Dispersed PANFs were then combined with PMMA/butanone solution. Additional sonication and posterior film cast from solution procedures resulted in slight green PMMA/PANFs 0.15-0.30% (wt/wt) composite films. Film composites were characterized by UV-Vis spectroscopy and Scanning Electron Microscopy (SEM). PANFs powder was investigated by (SEM).An investigation by viscosity method on molecular structure of neat PMMA exposed to ultrasonic irradiation up to 2 h showed small change (<5%) in the viscosity-average molar mass, Mv (≈100 kg/mol). It suggests that mechanical degradation by cavitation does not occur on PMMA under those conditions. Thus, ultrasonic bath treatment is a simple, accessible method for mitigating solubility problems of PANI doped with inorganic acids and improving quality of low concentration PMMA/PANI composites. Application of these composites relies on the radiolytic stabilization effects of PANI on PMMA matrix.     

Gd2O3:Yb3+,Er3+上转换纳米纤维的制备与表征

采用溶胶-凝胶法与静电纺丝技术相结合制备了PVA/[Gd(NO3)3+Yb(NO3)3+Er(NO3)3]复合纳米纤维,将其进行热处理,得到Gd2O3:Yb3+,Er3+上转换纳米纤维.采用XRD、SEM、TG-DTA、FTIR和荧光光谱对样品进行了表征.结果表明:复合纳米纤维为无定型,Gd2O3:Yb3+,Er3+上转换纳米纤维属于体心立方晶系,空间群为Ia3.复合纳米纤维的平均直径约为140nm,经过600℃焙烧后,获得了直径约60nm的Gd2O3:Yb3+,Er3+上转换纳米纤维.当焙烧温度高于600℃时,复合纳米纤维中水分、有机物和硝酸盐分解挥发完毕,样品不再失重,总失重率为81%.复合纳米纤维的红外光谱与纯PVA的红外光谱一致,600℃以上时,生成了Gd2O3:Yb3+,Er3+上转换纳米纤维.该纤维在980nm激光激发下发射出中心波长为522nm、560nm的绿色和659nm的红色上转换荧光,对应于Er3+离子的2H11/2/4S3/2→4Il5/2跃迁和4F9/2→4Il5/2跃迁.在Gd2O3:Yb3+,Er3+上转换纳米纤维形成过程中,PVA分子起到了导向模板作用.PVA/[Gd(NO3)3+Yb(NO3)3+Er(NO3)3]复合纳米纤维在热处理过程中,PVA分解挥发,稀土硝酸盐分解并氧化生成Gd2O3:Yb3+,Er3+纳米颗粒,这些纳米颗粒相互联结起来形成了Gd2O3:Yb3+,Er3+上转换纳米纤维.     

Synthesis and characterization of electrospun cadmium sulfide- and lead sulfide-blended poly(vinyl acetate) composite nanofibers

We report the preparation of cadmium sulfide (CdS) and lead sulfide (PdS) nanoparticle-blended poly(vinylacetate) (PVA) composite nanofibers by using an electrospinning technique. The resultant nanofibers were observed to be very smooth with uniform diameters ranging from 100 to 400 nm. The detailed analyses such as surface morphology, structure, bonding configuration, thermal, optical and electrical properties of the electrospun composite nanofibers were characterized. The introduced CdS and PdS nanoparticles in PVA were significantly enhanced by the electrical property of the composite nanofibers. The electrical conduction mechanism was further evaluated by studying the Fowler–Nordheim plots. Overall, the feasibility of obtaining uniformly dispersed CdS and PdS nanoparticles in PVA nanofibers can be useful for the realization of various nanotechnological device applications.     

Semiconducting ZnO Nanofibers as Gas Sensors and Gas Response Improvement by SnO2 Coating

ZnO nanofibers were electro‐spun from a solution containing poly 4‐vinyl phenol and Zn acetate dihydrate. The calcination process of the ZnO/PVP composite nanofibers brought forth a random network of polycrystalline würtzite ZnO nanofibers of 30 nm to 70 nm in diameter. The electrical properties of the ZnO nanofibers were governed by the grain boundaries. To investigate possible applications of the ZnO nanofibers, their CO and NO₂ gas sensing responses are demonstrated. In particular, the SnO2‐deposited ZnO nanofibers exhibit a remarkable gas sensing response to NO2 gas as low as 400 ppb. Oxide nanofibers emerge as a new proposition for oxide‐based gas sensors.     

Stretchable and Self-Healable Semiconductive Composites Based on Hydrogen Bonding Cross-linked Elastomeric Matrix

Semiconductors with both high stretchability and self-healing capability are highly desirable for various wearable devices. Much progress has been achieved in designing highly stretchable semiconductive polymers or composites. The demonstration of self-healable semiconductive composite is still rare. Here, an extremely soft, highly stretchable, and self-healable hydrogen bonding cross-linked elastomer, amide functionalized-polyisobutylene (PIB-amide) is developed, to enable a self-healable semiconductive composite through compounding with a high-performance conjugated diketopyrrolopyrrole (DPP-T) polymer. The composite, consisting of 20% DPP-T and 80% PIB-amide, shows record high crack-onset strain (COS ≈1500%), extremely low elastic modulus (E≈1.6 MPa), and unique ability to spontaneously self-heal atroom temperature within 5 min. Unlike previous works, these unique composite materials also show strain-independent charge mobility. An in-depth morphological study based on multi-model techniques indicate that all composites show blending ratio- and stretching-independent fibril-like aggregation due to the strong hydrogen bond in elastomer to enable the unique stable charge mobility. This study provides a new direction to develop highly healable and electronically stable semiconductive composite and will enable new applications of stretchable electronics.     

高导热聚合物基复合封装材料及其应用

微电子封装密度的提高对传统环氧塑封料的导热性能提出了更高的要求,将高导热的陶瓷颗粒/纤维材料添加到聚合物塑封材料中可获得导热性能好的复合型电子封装材料。文章结合高导热环氧塑封材料的研究工作,评述了高热导聚合物基复合封装材料的材料体系、性能特点和在微电子封装中的应用情况。分析讨论了影响聚合物基复合电子封装材料导热性能和介电性能的因素,提出了进一步提高聚合物基复合电子封装材料导热性能的途径。