电纺丝纳米纤维的制备、组装与性能

【作者】 伍晖；

【导师】 潘伟；

【作者基本信息】 清华大学 ， 材料科学与工程， 2009， 博士

【摘要】 本论文以电纺丝为平台,制备了多种功能无机、金属、高分子材料的一维纳米结构,研究了纳米结构的定向组装和物理性质,并探索了这些纳米结构在传感、微电子器件、仿生表面等方面的应用,取得了一些有意义的结果：陶瓷纳米纤维将电纺丝技术与溶胶-凝胶工艺结合,制备得到多种功能氧化物陶瓷纳米纤维。重点研究了电纺丝ZnO纳米纤维的光学、电学性能,制备成功单根ZnO纳米纤维沟道场效应晶体管(FET)器件和纳米纤维p-n异质结二极管器件。研究了电纺丝TiO2纳米纤维的力学性能。发现TiO2纳米纤维在室温下表现出异乎寻常的柔韧性。在电镜中对单根纳米纤维原位操纵弯曲试验,发现多晶TiO2纳米纤维表现出超弹性。针对这种特殊的力学性能,我们提出了应力诱导相变理论,并用多种手段证实我们的理论。将电纺丝技术的外延进一步扩大,首次获得了Ⅲ族氮化物纳米纤维。电纺丝合成的GaN纳米纤维能够方便的形成取向阵列,在此基础上我们制备了GaN纳米纤维沟道FET器件。GaN纳米纤维表现出很好的光敏特性。金属纳米纤维基于电纺丝,创新性的获得了多种金属一维纳米结构。获得了具有高导电率的Ag基金属纳米纤维和金属Fe、Co、Ni单质纳米纤维。研究了磁性金属纳米纤维及其阵列的室温和低温磁学性能。利用电纺丝纤维为模板成功得到尺寸均一,具有极高长径比的Cu、Ni等金属纳米管。使用去合金化方法对Cu-Ni合金纳米管进行处理得到表面具有纳米多孔结构的多孔Cu纳米管。多孔Cu纳米管具有非常高的SERS活性,有望发展成为一种新型高灵敏度SERS基底。高分子纳米纤维通过对电纺丝装置的设计和改进,获得了多种仿生结构的纳米纤维阵列,成功的模拟了荷叶表面、稻叶表面、羽毛表面和水黾的微观结构和表面特性,实现了多种特殊浸润性。更多还原

【Abstract】 The design, preparation and controlled assembly of functional one-dimensional (1D) nanostructure has attracted considerable attention because of their unique electrical, optical and magnetic properties different from that of bulk and nanoparticles as well as their potential applications in optics, optoelectronics, catalysis and sensors. Nanowires or nanofibers offer the opportunity to investigate electrical and mechanical properties in size-confined systems, with the possibility of providing a deep understanding of physics at the nano-scale. The main challenge in this area is how to precisely control the sizes, dimensionalities, compositions and orientations of nanowires, which may serve as a powerful tool for the tailoring of physical/chemical properties of materials in a controllable way. In this dissertation, valuable explorations have been carried out on the new synthetic and assembly of functional nanofibers via electrospinning. The physical properties and practical applications of these nanostructures have also been investigated.Cermic NanofibersWe fabricated semiconductive oxide and nitrate nanofibers using a simple electrospinning method combined with sol-gel processing and post heat treatment. The synthesized nanofibers have diameters below 100 nm, and length over 1 cm. The morphologies of the oxide nanofibers, including diameters and surface roughness, can be tuned easily. Highly oriented ceramic nanofibers with a length of several centimeters are fabricated using a newly modified electrospinning method.The optical and electrical transport properties of these semiconductive nanofibers were investigated. Functional devices, including p-type and n-type field-effect transistors, p-n junction diodes and high sensitive UV light detectors had been assembled from oriented cermic nanofibers. The mechanical properties of oxide nanofibers were studied. We found novel super-elastic properties in TiO2 nanofibers. The mechanisms in this interesting phenomenon were discussed.Metallic Nanofibers and NanotubesA general synthetic method had been developed to fabricate and assemble ferromagnetic transition metal nanofibers. By employing the novel electrospinning technique followed by subsequent heat treatment, we have successfully prepared uniform nanofibers of Cu, Fe, Co, Ni and Ag/NiO with diameters of-25 nm and lengths longer than 100μm. The electrical transport properties of Cu and Ag/NiO nanofibers, as well as the magnetic properties of Fe, Co and Ni nanofibers were studied.Uniform metallic nanotubes with high aspect ratio and controllable morphologies and orientations were synthesized employing electrospun nanofibers as template. These metal nanotubes show very high SERS activities.Polymer NanofibersFast and easy construction of biomimetic surfaces with controlled wettability was accomplished through electrospinning. The topography and wetting properties of biosurfaces including lotus leaves, bamboo leaves, goose feathers and water strider’s legs were mimicked with different patterns of electrospun polymer nanofibers. Surfaces with anisotropic wetting in two or three directions, as well as artificial water strider’s legs with maximal supporting force of more than 200 dynes cm-1 were facilely fabricated based on an electrospinning technique combined with aborative designed nanofiber collectors. We believe these polymer nanofiber patterns will help the design of smart, fluid-controllable interfaces that may be applied in novel microfluidic devices and directional, easy-cleaning coatings.更多还原