静电诱导自组装碳纳米管薄膜的结构表征与电学性能

Structure characterization and electric properties of electrostatic-induced self-assembly carbon nanotube films

为了给高性能微机电系统(MEMS)薄膜器件提供复合功能薄膜材料,本文将功能化碳纳米管与聚电解质溶液交互沉积技术用于静电诱导逐层自组装碳纳米管/聚合物薄膜。对薄膜制备及其性能的可调控性进行了表征和测试。扫描电镜显微(SEM)形貌观察表明,碳纳米管与聚合物分子链结合致密,形成了质地均匀的随机碳纳米管网络结构。拉曼光谱结果表明,碳纳米管在径向呼吸、缺陷振动、拉伸振动等模式下的指纹特征光谱证实了碳纳米管的有效组装和加载。用石英晶体微天平(QCM)对碳纳米管/聚合物薄膜自组装过程进行了在线实时监测,结果揭示了沉积薄膜厚度和薄膜结构的可调控性。当聚电解质层数由0递增到5时,子层膜厚由6.31nm增加到111.59nm,碳纳米管加载体积比由72.35%减小到14.78%。此外,基于I-V表征研究了碳纳米管填充体积比及其薄膜厚度对碳纳米管/聚合物薄膜电学特性的影响,为实现碳纳米管/聚合物薄膜电学性能的可调节性提供了实验及理论依据。

To provide building blocks for high-performance Micro-electro-mechanical System （MEMS） devices, Layer-by-layer （LbL） self-assembly of Single-walled Carbon Nanotube （SWNT）/polymer films was proposed and their properties were characterized and tested. The surface morphologies of the SWNT/polymer films observed under a Scanning Electron Microscope（SEM） show high strength, dense and random network structures. Raman spectra of all characteristic peaks for the SWNT in radial breathing mode, disorder mode and tangential mode demonstrate the presence of the SWNT in overall good quality and a loading state. Real time Quarts Crystal Microbalance（QCM） online monito ring illustrates that the deposition thickness and the SWNT loading fraction in the nanocomposite can be controlled in a large range based on LbL sequential deposition process. When the cycle number of polymers increase from 0 to 5, the average film thickness increases from 6.31 to 111.59 nm, and the SWNT volume fraction decreases from 72.35% to 14.78 %. In addition, the electric properties of the SWNT/polymer films under the influence of SWNT loading fraction and film thickness were investigated through current-voltage characterization. These results provide experimental and theoretical bases for potential applications of SWNT films in MEMS devices.